Methods for monitoring fat crystallization under shear for … · 2012-03-14 · Faculteit Bio-ingenieurswetenschappen Academiejaar 2010 – 2011 Methods for monitoring fat crystallization

Faculteit Bio-ingenieurswetenschappen

Academiejaar 2010 – 2011

Methods for monitoring fat crystallization under shear for margarine applications

Elien Verstraete Promotor: Prof. dr. ir. Koen Dewettinck Tutors: ir. Nathalie De Clercq dr. ir. Veerle De Graef

Masterproef voorgedragen tot het behalen van de graad van

Master in de bio-ingenieurswetenschappen: Levensmiddelenwetenschappen en

voeding

The author and promotor give permission to put this thesis to disposal for consultation and to copy

parts of it for personal use. Any other use falls under the limitations of copyright, in particular the

obligation to explicitly mention the source when citing parts out of this thesis.

De auteur en de promotor geven de toelating dit werk voor consultatie beschikbaar te stellen en delen

ervan te kopiëren voor persoonlijk gebruik. Elk ander gebruik valt onder de beperkingen van het

auteurs recht, in het bijzonder met betrekking tot de verplichting uitdrukkelijk de bron te vermelden bij

het aanhalen van resultaten van dit werk.

Gent, juni 2011

The promoter,

Prof. dr. ir. Koen Dewettinck

The author,

Elien Verstraete

Woord vooraf | I

Woord vooraf

Het is zo ver, na 5 jaar studeren en een thesis ben ik gekomen aan het einde van deze studie en het is

echt voorbij gevlogen! Ook dit jaar was een hele ervaring en heb ik immens veel bijgeleerd. Dit heb ik

natuurlijk niet op mijn eentje gedaan en daarom wil ik hier enkele mensen bedanken.

In de eerste plaats wil ik mijn promotor, prof. dr. ir. K. Dewettinck bedanken om mij de kans te geven

mij te mogen verdiepen in de margarine wereld. Het was een uitdagend onderwerp maar dit heeft er

voor gezorgd dat dit een unieke ervaring werd.

Daarnaast wil ik zeker en vast mijn tutors, Nathalie en Veerle, bedanken. Ik kon altijd op hen rekenen

en geen vraag was hen teveel. Ik wil hen ook bedanken voor de opmerkingen en tips bij het schrijven

van mijn thesis, zonder hen zou dit boekje er niet gelegen hebben.

Deze thesis zou ook niet mogelijk geweest zijn zonder de samenwerking met Vandemoortele NV. Zij

hebben mij de kans gegeven om naast het labowerk aan de universiteit ook al eens te proeven hoe het

er in de industrie aan toe gaat. Hierbij wil ik vooral Ans bedanken. Ik kon altijd terecht bij haar met al

mijn vragen en ze gaf me veel goede raad, ook bij het schrijven van mijn thesis. Ook de mensen van het

R&D labo, en in het bijzonder Joost, om mij wegwijs te maken in het labo en met te helpen bij mijn

analyses. De mensen van de pilot mag ik ook niet vergeten te bedanken om de pilot testen in goede

banen te leiden.

Verder wil ik ook de doctoraatstudenten en de laboranten bedanken voor de leuke sfeer en de gezellig

babbels in het labo, ook voor de hulp wanneer er eens iets niet lukte. In het bijzonder wil ik Benny

bedanken voor het oplossen van alle praktische zaken en voor de hulp tijdens de Schröder testen.

Ook de andere thesisstudenten mag ik niet vergeten, bedankt voor alle toffe babbels en om tussen het

‘serieuze’ labowerk ook voor wat ontspanning te zorgen. Ik wil speciaal hierbij Liesbeth bedanken voor

de vele leuke gesprekken, Ik kon altijd op je rekenen, merci hiervoor!

Zowel deze thesis als de voorbije 5 jaar zou niet gelukt zijn zonder de steun van mijn ouders. Ook de

laatste weken toen de stress zijn maximum bereikte, stonden zij klaar voor mij.

MERCI ALLEMAAL!!

Elien

Table of content | II

Table of content

Woord vooraf .............................................................................................................................................. I

Table of content ......................................................................................................................................... II

List of abbreviations ................................................................................................................................... V

List of figures ............................................................................................................................................. VI

List of tables ............................................................................................................................................ VIII

Abstract ..................................................................................................................................................... IX

Samenvatting .............................................................................................................................................. X

1 Introduction ........................................................................................................................................ 1

2 Literature review ................................................................................................................................ 2

2.1 Margarine ................................................................................................................................... 2

2.1.1 The structure of margarine ................................................................................................ 2

2.1.2 Production .......................................................................................................................... 3

2.1.3 Types of margarines ........................................................................................................... 6

2.1.4 Quality parameters ............................................................................................................. 8

2.1.5 Influencing factors of the process on the margarine structure & functionality .............. 10

2.2 Palm oil and its fractions .......................................................................................................... 13

2.3 Shea stearin .............................................................................................................................. 14

3 Materials and methods .................................................................................................................... 15

3.1 Samples .................................................................................................................................... 15

3.1.1 Reference samples ........................................................................................................... 15

3.1.2 Cake margarine based samples ........................................................................................ 15

3.2 Chemical composition samples ................................................................................................ 16

3.2.1 Fatty acids ......................................................................................................................... 16

3.2.2 TAGs .................................................................................................................................. 16

3.2.3 SFC .................................................................................................................................... 17

3.3 Crystallization under shear: fundamental study ...................................................................... 17

Table of content | III

3.3.1 Oscillatory rheology .......................................................................................................... 17

3.3.2 Rheo-NMR ........................................................................................................................ 17

3.4 Crystallization under shear: applied study ............................................................................... 18

3.4.1 Rapid Viscosity Analyzer (RVA) ......................................................................................... 18

3.4.2 Controlled temperature shearing unit (CTSU) ................................................................. 19

3.4.3 TNO cell ............................................................................................................................ 20

3.4.4 Pilot Vandemoortele ........................................................................................................ 20

3.4.5 Pilot UGent ....................................................................................................................... 20

3.5 Evaluation of the crystallized fat blends and cake margarine as function of storage time ..... 20

3.5.1 SFC .................................................................................................................................... 20

3.5.2 Hardness ........................................................................................................................... 21

3.5.3 Microscopy ....................................................................................................................... 21

3.5.4 Water droplet size ............................................................................................................ 21

3.6 Sponge cakes ............................................................................................................................ 22

3.6.1 Preparation of the sponge cakes ...................................................................................... 22

3.6.2 Photographic images of the cake volumes ....................................................................... 22

3.6.3 Hardness ........................................................................................................................... 22

3.7 Statistical analyses .................................................................................................................... 22

4 Results and discussion ...................................................................................................................... 23

4.1 Part 1: Crystallization under shear: fundamental study .......................................................... 23

4.1.1 Characterization of the fat blends .................................................................................... 23

4.1.2 Fundamental study of crystallization under shear ........................................................... 26

4.2 Part 2: Crystallization under shear: applied study ................................................................... 35

4.2.1 Rapid Viscosity Analyzer (RVA) ......................................................................................... 35

4.2.2 RVA followed with a post treatment ................................................................................ 36

4.2.3 Controlled Temperature Shearing Unit (CTSU) ................................................................ 36

4.2.4 Comparison of RVA and CTSU .......................................................................................... 36

4.2.5 CTSU with similar conditions of the RVA .......................................................................... 37

Table of content | IV

4.2.6 CTSU - influence of the rotational speed ......................................................................... 39

4.2.7 CTSU – influence of the length of the shearing phase ..................................................... 39

4.3 Part 3: Lab scale versus pilot scale ........................................................................................... 41

4.3.1 General overview of the three crystallizers and the experimental set-up ...................... 41

4.3.2 Microstructural characterization of the fat blends .......................................................... 43

4.3.3 Evaluation of the fat blends and margarine samples as function of storage time .......... 46

4.3.4 Water droplet size distribution ........................................................................................ 56

4.3.5 Cake tests ......................................................................................................................... 57

5 Conclusions ....................................................................................................................................... 60

6 Further research ............................................................................................................................... 62

7 References ........................................................................................................................................ 63

Appendix................................................................................................................................................... 66

List of abbreviations | V

List of abbreviations

CBE Cocoa butter equivalent

CS Cooling step

CTSU Controlled temperature shearing unit

GC Gas chromatography

HPLC High pressure liquid chromatography

IT Intermediate treatment

IV Iodine value

L Lauric acid

Marg Margarine

MargFat Margarine fat

NMR Nuclear magnetic resonance

O Oleic acid

P Palmetic acid

PLM Polarized light microscopy

Pst Palm stearin

PT Post treatment

RT Resting tube

RVA Rapid viscosity analyzer

S Stearic acid

SFC Solid fat content

Shst Shea stearin

SSHE Scraped surface heat exchanger

TAG Triacylglycerol

List of figures | VI

List of figures

Figure 2.1: Principal steps of margarine production (after Bockisch, 1998) ........................................... 3

Figure 2.2: Cross section of a SSHE (after Bockisch, 1998) ..................................................................... 5

Figure 2.3: Photograph of the inside of a pin worker (after Vandemoortele) ........................................ 6

Figure 2.4: Multistage dry fractionation process of palm oil (PMF: palm mid fraction; IV: iodine value)

(after Kellens et al, 2007) ...................................................................................................................... 14

Figure 3.1: The configuration used to apply shear to the sample while it crystallizes in a water bath

(after Vereecken, 2010) ......................................................................................................................... 18

Figure 3.2: RVA with corresponding disposable RVA-cell (Vereecken, 2010) ....................................... 18

Figure 3.3: The stirrer and scraping device of the CTSU (left) and the entire CTSU (right) .................. 19

Figure 4.1: The schematic overview of the research ............................................................................ 23

Figure 4.2: SFC as a function of temperature (°C) for the different fat blends ..................................... 26

Figure 4.3: Rheo-NMR of the fat blends with (a) shea stearin and (b) palm stearin ............................ 27

Figure 4.4: Complex modulus (|G*|) as a function of isothermal time for all fat blends for

crystallization without shear ................................................................................................................. 29

Figure 4.5: Apparent viscosity recorded during the shearing step in function of the isothermal time of

(a) Shst15, (b) Pst15 (c), Shst20 and (d) Pst20 ...................................................................................... 30

Figure 4.6: |G*| in function of the isothermal time of Shst15(d, e, f) and Shst20(a, b, c) recorded after

a shear step of 15min (a, d), 30min (b, e) and 60min (c, f) ................................................................... 32

Figure 4.7: |G*| in function of the isothermal time of Pst15 (d, e, f) and Pst20 (a, b, c) recorded after

a shear step of 15min (a ,d), 30min (b,e) and 60min (c,f) ..................................................................... 34

Figure 4.8: Time-temperature profile used for the crystallization of the samples at 15°C under shear

............................................................................................................................................................... 35

Figure 4.9: Comparison RVA and CTSU @ 51rpm on fat blend Shst20 (NG=no grains, SA=sandiness,

BG=big grains) ....................................................................................................................................... 38

Figure 4.10: Comparison CTSU @ 51rpm and @ 115rpm on fat blend Shst20 (NG=no grains,

SA=sandiness) ........................................................................................................................................ 39

Figure 4.11: Shst20 - longer period of shear (NG=no grains, SA=sandiness) ........................................ 40

Figure 4.12: Scheme of the different steps in the PilotVDM, PilotFTE and CTSU ................................. 42

List of figures | VII

Figure 4.13: Comparison of the microstructure (PLM) of samples made with the CTSU, PilotFTE and

PilotVDM. (a) Shst20 PilotVDM PT (left) – CS1 (right), (b) Shst20 CTSU 2h (left) – 30’ (right). The

arrows indicate some air bubbles. ........................................................................................................ 44


PilotVDM. (a) Marg25 CTSU (left) – PilotVDM CS1 (right), (b) Marg15 CTSU (left) – PilotFTE PT (right).

The arrows indicate some air bubbles. ................................................................................................. 45


PilotVDM. (a) MargFat10 CTSU (left) – PilotVDM CS2 (right), (b) Pst10 CTSU (left)– PilotFTE CS (right).

The arrows indicate some air bubbles and the circles indicate some grains. ....................................... 46

Figure 4.16: Hardness (N) and SFC (%) in function of the storage time for the comparison of (a) CTSU

Pst10 – PilotFTE CS and (b) CTSU Pst15 – PilotFTE PT ........................................................................... 48

Figure 4.17: The evaluation of the different steps in the PilotFTE for the palm stearin blend after 1

week ...................................................................................................................................................... 51

Figure 4.18: The evaluation of the different steps in the PilotVDM for margarine fat after 1 week ... 52

Figure 4.19: Hardness (N) and SFC (%) in function of the storage time for the comparison of CTSU

Marg15 – PilotFTE CS, PT ....................................................................................................................... 53

Figure 4.20: Hardness (N) and SFC (%) in function of the storage time for the comparison of (a) CTSU

Marg15 – PilotVDM CS2, CS3, CS4, (b) CTSU Marg20 – PilotVDM RT, (c) CTSU Marg25 - PilotVDM CS1

............................................................................................................................................................... 54

Figure 4.21: The evaluation of the different steps in (a) PilotFTE and in (b) PilotVDM for margarine

after 1 week ........................................................................................................................................... 56

Figure 4.22: Photographs of the loaf size of sponge cake with (a) PilotMarg1, (b) CTSU15°C_30’,

(c)CTSU15°C_1h, (d)PilotMarg2, (e)CTSU20°C_30’ and (f)CTSU20°C_1h ............................................. 58

Figure 4.23: (a) Hardness of the cakes made with different margarines and (b) the linear correlation

between hardness and the dough density ............................................................................................ 59

List of tables | VIII

List of tables

Table 2.1: Average Composition of European Type Margarines ............................................................. 3

Table 3.1: Composition of the different reference samples (Vereecken, 2010) ................................... 15

Table 4.1: Composition of the fat blends .............................................................................................. 24

Table 4.2: Fatty acid (%) profile of the different fat blends .................................................................. 24

Table 4.3: TAG (%) composition of the different fat blends .................................................................. 25

Table 4.4: Comparison of the RVA and the CTSU technique ................................................................. 37

Table 4.5: The different temperatures used on the CTSU to compare with the products on both pilot

scales ..................................................................................................................................................... 42

Table 4.6: The comparison between the CTSU and the PilotVDM for the blend with palm stearin .... 50

Table 4.7: The D3,3, standard deviation and 97,5% values (µm) of different margarine samples ....... 57

Abstract | IX

Abstract

When a new margarine is made or an existing margarine is reformulated, it has to be tested before it

is produced on industrial scale. This is done on pilot scale but these tests still need a lot of fat

ingredients and time. In this study a method was developed to produce margarine products on lab

scale as an alternative to pilot scale. In the first part a fundamental study was executed on

crystallization under shear by measuring the solid fat content (SFC) with rheo-NMR and rheological

parameters with oscillatory rheology. The crystallization was enhanced by shear; this was seen by a

faster increase and a higher final SFC. The procedure of the oscillatory rheology started with a cooling

step, followed by a shear step with different shear rates and shear times, and at the end an

isothermal period without shear. All fat blends showed an earlier increase in apparent viscosity at

higher shear rates due to a faster crystallization. However, the higher the shear rate, the smaller the

increase in apparent viscosity, resulting in a lower equilibrium value for the samples at higher shear

rates. In the step without shear, the complex modulus went fast to an equilibrium for all shear rates

in the shea stearin blends. The complex modulus of the palm stearin blends increased but much

slower.

In the second part of the research a method was developed and optimized on lab scale. The first two

techniques were the rapid viscosity analyzer (RVA) and the RVA with the TNO cell, both techniques

developed grains in the shea stearin samples during storage. Further optimization was not possible

due to the limitations of the device. Another technique that was used, was the controlled

temperature shearing device (CTSU). The procedure was optimized by using higher shear rates and

longer shear times which resulted in samples without grains in the shea stearin blend during storage.

In the third part, the CTSU was compared with the pilot of Vandemoortele and the pilot of FTE. The

samples were evaluated by measuring the solid fat content and the hardness, and by polarized light

microscopy. The results of the fat blends of the CTSU showed many differences with both pilots due

to the air bubbles captured in the samples, as seen by polarized light microscopy and reflected in the

low hardness values. The margarine samples showed that the differences in hardness and solid fat

content were much smaller between the different set ups. The water droplet size distribution,

measured by a nuclear magnetic resonance technique, was the lowest for the pilot of Vandemoortele

due to the highest shear forces, and the highest for the CTSU samples. At the end, the margarines

were compared on the consumer level by preparing cakes. The cakes were visually evaluated and the

hardness was measured. The cakes of the CTSU and the pilot of Vandemoortele did not show many

differences. The CTSU was thus not suitable to crystallize fat blends that are similar with the pilot

scale. However the margarine products on the CTSU showed a lot of similarities with the margarine

on the pilots and even on consumer level, almost no differences were observed.

Samenvatting | X

Samenvatting

Wanneer een nieuwe margarine wordt gemaakt of een bestaand recept wordt aangepast, moet dit

product getest worden voordat het geproduceerd wordt op industriële schaal. Dit gebeurt op piloot

schaal, maar voor deze tests zijn veel grondstoffen en tijd nodig. In deze studie werd een methode

ontwikkeld om margarine te produceren op laboschaal als alternatief voor piloot schaal. In het eerste

deel werd een fundamenteel onderzoek uitgevoerd over kristallisatie onder afschuiving door middel

van het meten van het vastvetgehalte (SFC) met rheo-NMR en reologische parameters met oscillerende

reologie. De kristallisatie werd versneld door afschuiving, dit werd gezien door een snellere toename en

een hoger eind SFC. De procedure van de oscillerende reologie start met een koelstap, gevolgd door

een stap onder afschuiving met variërende afschuifsnelheden en -tijden, en aan het eind een isotherme

periode zonder afschuiving. Alle vetmengsels toonden een snellere toename van de schijnbare

viscositeit bij hogere afschuifsnelheden als gevolg van een snellere kristallisatie. Echter, hoe hoger de

afschuifsnelheid, hoe kleiner de toename van de schijnbare viscositeit en dit resulteert in een lagere

evenwichtswaarde voor de stalen met hoge afschuifsnelheden. In de stap zonder afschuiving, ging de

complexe modulus snel naar een evenwicht voor alle afschuifsnelheden bij de shea stearine mengsels.

De complexe modulus van de palm stearine mengsels stijgt, maar veel langzamer. In het tweede deel

werd een methode ontwikkeld en geoptimaliseerd op laboschaal. De eerste twee technieken waren de

Rapid Viscosity Analyzer (RVA) en de RVA met de TNO cel, beide technieken ontwikkelden korrels in de

shea stearine stalen tijdens de opslag. Een andere techniek die werd gebruikt, was de controlled

temperature shear unit (CTSU). De procedure werd geoptimaliseerd door middel van hogere

afschuifsnelheden en langere afschuiftijden, dit resulteerde in shea stearine stalen die geen korrels

ontwikkelden tijdens de bewaring. In het derde deel werd de CTSU vergeleken met de piloot van

Vandemoortele en de piloot van FTE. De stalen werden geëvalueerd door middel van het

vastvetgehalte, de hardheid en gepolariseerd licht microscopie. De resultaten van de vetmengsels van

de CTSU toonde veel verschillen met beide piloot opstellingen, dit was te wijten aan luchtbellen in de

stalen, zoals gezien bij gepolariseerd licht microscopie en in de lage waarden van de hardheid.

Margarine toonde veel minder verschillen tussen de opstellingen. De waterdruppelgrootte verdeling,

gemeten door een nucleaire magnetische resonantie techniek, was de laagste voor de piloot van

Vandemoortele door de hoge afschuifkrachten, en het hoogst voor de CTSU stalen. Aan het eind

werden de margarines vergeleken op consument level door het bereiden van cakes. Deze werden

visueel beoordeeld en de hardheid werd gemeten. De cakes van de CTSU en de piloot van

Vandemoortele vertoonden weinig verschillen. De CTSU was dus niet geschikt om vetmengsels te

produceren die vergelijkbaar zijn met de piloot schaal. Echter, de margarineproducten op de CTSU

toonden veel gelijkenissen met die op de piloot en op consument level werden er nagenoeg geen

verschillen waargenomen.

Introduction | 1

1 Introduction

On an industrial scale, the margarine production exists out of a sequence of surface scraped heat

exchangers and pin workers and sometimes a resting tube is used. The emulsion is cooled,

crystallized and treated until the desired product is obtained. The aim of this research was to develop

a method to produce margarine on lab scale with similar properties as the product on pilot scale. The

research was divided in three main parts, the first part was a more fundamental research of fat

crystallization under shear, in the second part the aim was to find a suitable method on lab scale to

find an alternative for the pilot production and in the last part, the results on the controlled

temperature shearing unit (CTSU) was compared with these on the pilot of Vandemoortele

(PilotVDM) and the pilot of FTE (PilotFTE). The research was in cooperation with the company

Vandemoortele NV.

In the first part samples were first chemically characterized followed by a more fundamental

investigation of the crystallization of fat under shear by rheo-NMR method and oscillatory rheology.

In the second part, the aim was to find an alternative for production on pilot scale. Methods were

evaluated by measuring the hardness, SFC. The appearance of grains was also used as evaluation

criteria. This part was a continuation of the experiments of the PhD of Jeroen Vereecken (2010). The

selected method was then used in the third part.

In the last part, the selected method, the CTSU was applied both on the selected fat blends as on an

existing recipe of a cake margarine. The obtained results were compared with products produced on

the PilotVDM (5 steps) and the PilotFTE (2 steps). The comparison was done by measuring the

hardness and SFC during two weeks, the appearance of grains was also examined. In the end, the

samples of the CTSU and the pilots were compared with a polarized light microscope. The

applicability of the produced margarines on the CTSU and the PilotVDM was evaluated in a baking

test.

Literature review | 2

2 Literature review

2.1 Margarine

Margarine was invented in the 19th century because of the desire to have a product similar to butter

but available in higher quantities at a lower price. Margarine is cheaper because the raw materials

are cheap and available in larger quantities. In many European countries, the launch of margarine

was not appreciated by the butter producers. They saw margarine as an imitation product of butter.

The big difference between butter and margarine is the source of the raw materials. Butter is made

with fatty cream of cow’s milk and margarine with vegetable oils or in the beginning with animal fat.

From the beginning, margarine has developed into a tailor-made fat product. Its properties can be

adjusted to the very different demands of catering, bakery and the households. (Bockisch, 1998)

2.1.1 The structure of margarine

According to the council regulation 2991/94 of the European Community concerning fats, margarine

is a water-in-oil emulsion with a fat content ranging from 80 to 90%. Most commonly margarines

consist of 80% fats and oils, and 20% of an aqueous phase. The fat phase is a network of fat crystals

and agglomerates of fat crystals with liquid oil in between. These agglomerates usually have a size of

15 – 20 µm (Dewettinck, 2010-2011). The fatty phase contains of the fat-soluble ingredients like fat-

soluble flavours, vitamins, colorants and emulsifiers. The aqueous phase contains maximum 16% of

water, the other 4% are the water-soluble ingredients. (Bockisch, 1998; Young & Wassell, 2008 and

Vereecken, 2010)

The aqueous phase contains the water-soluble ingredients such as salt, water-soluble flavours, milk

or milk solids and preservatives. The water droplet size is an important parameter because of its

influence on the microbial stability, the microstructure, and thus also the appearance and the taste

of the margarine (Van Dalen, 2002). Table 2.1 gives the average composition of European Type

margarines. (Bockisch, 1998)


Table 2.1: Average Composition of European Type Margarines

Component Amount Examples

Oils/fats (%) >80 Soybean oil, rapeseed oil, sunflower oil, palm oil, coconut oil,

palm kernel oil

Emulsifiers (%) 0.2-0.6 Lecithin, monoacylglycerols, monodiacylglycerols

Milk components (%) <6 Soured milk, butter milk, sour whey, sweet whey

Acids (%) 0.1-0.3 Citric acid solution, lactic acid solution

Salt (%) 0.1-0.3

Flavours (%) Traces Oil and water soluble

Preservatives (%) <0.12 Sorbic acid, benzoic acid (in half-fat margarines)

Water (%) To 100 Potable water

Vitamins (IU) 1500 Vitamin A

(IU) 100 Vitamin D

ppm 100-300 Vitamin E

Stabilizers In half-fat and low-fat margarines

Colorants Carotene

2.1.2 Production

The production of margarine consists of some principal steps starting from refined oils and fats

(Figure 2.1). The cooling steps and the mechanical treatments can occur in different orders. These

steps strongly influence the properties of the end product.

Figure 2.1: Principal steps of margarine production (after Bockisch, 1998)


During the production process, there are one or more treatment steps. The crystal network is than

intentionally destroyed to get a certain consistency. Important properties of margarine, such as

hardness and plasticity, are very dependent on the numbers of crystals, their size, polymorphism and

the binding force that exist in the system. The first crystals formed are mostly in the α-form, during

the process they transform to β’ crystals. These crystals provide a good spreadability and plasticity to

the margarine. However, a transformation of β’ to β crystals can occur during storage due to

temperature fluctuations. The formation of β crystals is undesired as it leads to graininess in the

margarine. (Dewettinck et al, 2010-2011; Njumbe Ediage, 2007)

2.1.2.1 Ingredient preparation and emulsifying

The first step in the production of margarine is blending the ingredients. It is important to know that

margarine consists of a fat-soluble and a water-soluble phase. The two phases are mixed together in

one batch at a temperature around 5°C higher than the melting point (Moustafa, 1992). The

emulsion is than pumped by means of a high-pressure pump into the scraped surface heat

exchanger. The aqueous phase has to be pasteurized for some recipes. (Bockisch, 1998)

2.1.2.2 Cooling and working of the emulsion

The crystallization process is a sequence of cooling steps that start the crystallization at different

temperature levels. There are also zones that allow further crystallization without cooling but with

mechanical stress to break up secondary bonds. The cooling is also necessary to remove heat of

crystallization. (Bockisch, 1998)

Nowadays there are two different processes for margarine making, namely the chilled drum process

and the process with scraped surface heat exchangers. The chilled drum process is the old process to

make margarine; the process with scraped surface heat exchangers is more universal. (Bockisch,

1998)

Chilled drum process

The chilling drum is cooled to -12 to -24 °C from the inside by ammonia or freon evaporation. A thin

layer (0,1-0,25mm) of the emulsion is brought onto the cooling surface of the drum. The cooling of

the emulsion takes place rapidly without agitation. It rotates horizontally and the cooled margarine is

scraped off after one rotation as a thin film or as thin flakes. The produced flakes will have to rest in

silos or trolleys to complete the crystallization. After hours of resting, the flakes are kneaded in a

vacuum kneading unit in order to remove the air between the flakes and to improve the structure of

the margarine. (Bockisch 1998; Hui and Clark, 2007; Vereecken, 2010)


Scraped surface heat exchangers process

In the first step of the scraped surface heat exchanger (SSHE) process, the single-ingredient solutions

and the fat blend are mixed and pumped into the SSHE or A-unit. The SSHE will cool and crystallize

the mixture. There are also pin workers in the process. The sequence of SSHE and pin workers in the

plant depends on the oil and fat composition, the desired product properties and the plant

throughput.

The SSHE (see Figure 2.2) consist of a tube with a cooling jacket on -25°C, cooled by ammonia. In the

tube is a shaft that rotates at high speed. The margarine emulsion is pumped through the annular

space; it is cooled on the inner surface of the tube and crystallizes. The cooling has to be well

controlled, it has to create many β’ crystal nuclei and the crystal growth has to be low. The shaft that

rotates in the tube has two to four rows of knives that worked the solidifying emulsion and prevents

the tube from being blocked by solidified product. The knives touch the inside of the tube and scrape

off the solid product of the wall.

Figure 2.2: Cross section of a SSHE (after Bockisch, 1998)

Together with the SSHE, the pin workers (see Figure 2.3) ensure the crystallization of the margarine.

A pin worker or a crystallizer is also a tube, containing an inner rotating shaft. The annular space in

the crystallizer is large compared with the coolers. Three rows of pins that are regularly distributed

on the tube, jut out from the inner tube wall, the shaft has also two rows of pins. These rotate with

the shaft through the gaps left by the pins fixed to the tube. The shear stress from treating the

product ensures the homogeneity of the emulsion and its plasticity. Crystallizers are not always

cooled. Besides the crystallization process, the mechanical heat and the latent heat of crystallization

will melt α crystals. To be sure that there is sufficient crystallization, the use of a resting tube or a B-


unit after the combination of crystallizers and coolers is used. The process parameters are adjusted

to the fat blends that are to be processed. This resting tube is important for some margarines, usually

for bakery margarines with high amounts of palm oil. (Moustafa, 1992; Bockisch, 1998 & Vereecken,

2010)

Figure 2.3: Photograph of the inside of a pin worker (after Vandemoortele)

2.1.3 Types of margarines

Before making margarine, it is important to know the type and application of the margarine so that

the functional properties required can be designed into the product. Optimum processing conditions

and fat blend are required to produce the desired quality margarine. In this section, the most

common margarine types are discussed. The solid fat content (SFC) and the melting point of the fat

phase will determine the structure characteristics and will distinguish the different margarines.

(Young & Wassell, 2007; Miskandar et al, 2005; Vereecken, 2010; Dewettinck et al, 2010-2011)

2.1.3.1 Retail margarine

Two types of retail margarines can be distinguished: table margarine and shallow frying margarine.

They are both spreadable at room temperature and maintain its shape at this temperature for a

certain time. Most table margarines are packed in plastic polypropylene tubs. This margarine has a

very similar consistency to butter and that gives the same functionality, but butter is not spreadable

straight from the refrigerator. The SFC curve of margarine has to be steep. When the margarine is

out of the fridge, it has to be spreadable. At room temperature (20°C), the product has to be stable

and resist to oil exudation. Between room temperature and body temperature (35 – 37°C), the SFC

should decrease dramatically to create a cooling effect in the mouth. The SFC at body temperature

provides information about the mouth feel and flavour release. (Miskandar et al, 2005; Nor Aini et al,

2007; Vereecken, 2010)


Margarine with a fat content lower than 80% is also on the market. Margarines that contain 60% of

fat are called three-quarter-fat margarine or reduced-fat margarine, a margarine that contains 40%

of fat is a half-fat margarine, low-fat margarine or light margarine. Recently, these margarines have

increased considerable in popularity because it gives the opportunity for reduced calorie intake while

maintaining good taste. In such reduced-fat products, the water phase has to be stabilized with

thickeners, as the emulsion and the crystal network alone are not able to guarantee temperature

stability and good shelf life properties. Half-fat margarines also contain preservatives; the water

droplet distribution is much coarser than with normal margarine and thus more sensitive toward

microorganisms. Even if produced and delivered in sterile conditions, quick spoilage occurs when the

margarine is not stored under proper conditions. (Young & Wassell, 2008; Hui, 1996)

2.1.3.2 Cream margarine

Cream margarine is used for fillings and toppings of cakes. It has to be whippable, which is achieved

mainly by the enormous number of fine β’-crystals. This margarine is characterized by a low melting

point (30-34°C), a high fat content and a quick melting in the mouth with a cooling effect. Coconut oil

is ideal for such products. (Dewettinck et al, 2010-2011; Bockisch 1998; Vereecken, 2010)

2.1.3.3 Bakery margarine and fats

Bakery margarines or industrial margarines have a higher melting point (34-45°C) than the products

produced for direct consumption, like table margarines. Bakery margarine is firmer, requires no

refrigeration and has not to melt in the mouth. It is developed to withstand dough working so it

separates the crumbs as long as possible by breaking the continuity of the protein starch structure.

Bakery margarine can be used in a wide range of applications and processes as they have different

functionalities, such as shortening power and lubricity, batter aeration, emulsifying properties,

improvements in keeping properties and flavour preservation. The most widely used bakery

margarines are the short pastry margarine, the cake margarine and the puff pastry margarine.

(Dewettinck et al, 2010-2011; Bockisch 1998; Vereecken, 2010)

2.1.3.4 Short pastry margarine

Short pastry margarine is used in a wide range of savoury and fruit products. The major ingredients

are flour, fat and water. The fat interrupts the gluten chain development and protects the flour

particles from the water. That results in planes of weakness and so the product becomes ‘shorter’

and more inclined to melt in the mouth. When there is too little fat a tough eating pastry will be

formed. If too much fat is present, the gluten development is interrupted and the dough will be loose

and soft to handle and too fragile when baked (Dewettinck et al, 2010-2011; Vereecken, 2010). A fat


for short pastry should have a firm consistency so that when being mixed into the dough, it retains

sufficient structure under shear conditions to be distributed as protective thin films and droplets

throughout the dough (Vereecken, 2010).

2.1.3.5 Cake margarine

The most important property of cake margarine is the incorporation of air. Sufficient liquid oil should

be available to envelop the air bubble and sufficient crystalline fat should be present to stabilize the

system. Small β’ crystals are the most effective in stabilizing air bubbles, as they can easily place

themselves on air-oil interface. The finer the fat and air distribution, the higher the final cake volume

will be. In addition to good aeration, margarine in cake also affects the crumb texture and the mouth

feel. (Bockisch, 1998; Dewettinck, 2010-2011; Vereecken, 2010)

2.1.3.6 Plastic margarine

Plastic margarine exists out of two margarines: the puff pastry and croissant margarine, both are

used for laminated dough. The most important property of plastic margarine is its toughness. The

products consist out of layers dough with a fat phase, like margarine, in between and is repeatedly

folded and rolled out. The margarine has to ensure that the many layers of the puff pastry stay

separated. The layer of margarine must not break, thus it should have a high plasticity. The melting

point is normally much higher than other bakery margarines (Bockisch, 1998).

2.1.4 Quality parameters

2.1.4.1 Chemical composition

The fat phase exists mainly out of TAGs that are composed of a glycerol backbone with three fatty

acids on. The properties of these TAGs are dependent of the number of carbon molecules, degree of

saturation and the dominant fatty acids. As the chain length decreases and the amount of double

bonds increases, the melting point of the TAG will decrease. Due to the health issues of margarine,

like higher cholesterol levels, cardiovascular disease, the food industry wants to decrease the

amount of saturated and trans-unsaturated fatty acids and increase the unsaturated fatty acids.

(Miskandar et al, 2005)

2.1.4.2 Solid fat content

The solid fat content (SFC) is the ratio of the solid phase to the total phase at a particular

temperature. SFC is an important property of a fat and thus is also an important quality parameter

for margarine. There are find strong correlations between the SFC and the plasticity of margarine.


The solid component forms a network and traps the liquid oil. This gives the plasticity and the

firmness to the product. The SFC has to be good to have good properties of the margarine. For

example, at 33,3°C the SFC of a table margarine has to be lower than 3,5% and at 37°C around 0%.

When this is the case, the margarine will melt cleanly in the mouth without a waxy aftertaste.

(Campos et al, 2002 & Miskandar et al, 2005)

2.1.4.3 Hardness

The hardness or consistency is a measurement of the texture of the margarine. The hardness is

dependent of the used fats and oils and the process conditions. The correlation between the

hardness and SFC is much debated. In general, the hardness was thought to be correlated with the

SFC of the margarine or shortening, but in few studies they found no correlation. For example

according to the study of Moziar et al (1989) the hardness of the margarine has no linear correlation

with the SFC. The reason can be that the hardness cannot be explained by one factor. It is also

dependent by the lipid composition, polymorphism, crystallization behaviour and the microstructure.

(Campos et al, 2002; Miskandar et al, 2005; Liu et al, 2010)

2.1.4.4 Polymorphism

Polymorphs are different forms of solid state (Timms, 1994). TAGs can crystallize in four major

polymorphs, namely sub-α, α, β’ and β. The α polymorph has the lowest melting point and is the

most unstable, it will mostly transform to a more stable polymorph. The β’ crystals are small (5-7µm),

needle-shaped or rod-shaped crystals. The β crystals are larger (20-30µm). Margarine has to be

smooth and without grains, this means small crystals. The fine crystals result in a good spreadability,

plasticity and good creaming properties which is the reason why margarine should exist out of β’

crystals (deMan, 1998). They give a smooth mouth-feel and give a better entrapment of the liquid oil

because of the forming of spherulitic structures. In contrast, β crystals give a brittle, grainy structure.

The polymorphic form of a fat is dependent on the composition of the fat and on the crystallization

conditions. A mixture of TAGs that are similar to each other will crystallize more rapidly in β crystals.

Heterogeneous TAGs are more stable in β’ crystals. Furthermore, palmitic acid standing on place 1

and 3 on the glycerol backbone will also helping to stabilize the β’ form (deMan, 1998). This is also

the reason why the industry is using more and more palm oil for margarines as it favors the

crystallization into the β’ form. (Campos et al, 2002 & Miskandar et al, 2005)


2.1.4.5 Water droplet size distribution

The water droplet size distribution of margarine is an important characteristic. It influences the

microbiological stability, the hardness, mouthfeel and flavour release of the margarine. A product

with a coarse water droplet distribution and with low amounts of preservatives and salt will be

susceptible to fast microbial contamination. The growth of the micro-organisms will be delayed by

water droplets smaller than 5µm (van Dalen, 2002; Freeman, 2005).

2.1.5 Influencing factors of the process on the margarine structure &

functionality

Besides the chemical properties of the fat blend, the process conditions have a major impact on the

finished product. Including the applied shear, the different temperatures and speeds along the

process will determine the properties of the margarine. Optimal processing conditions are very

important to obtain margarine with a good quality and storage stability.

2.1.5.1 Flow rate

There are two different flow rates that are important during the process, namely the pump speed

and the speed of the pin worker.

Pump speed

The emulsion flow rate is the speed of the emulsion from the mixing tank to the tube cooler. When

the flow rate is too slow, the emulsion is cooled very rapidly leading to a very fast crystallization rate.

This results in the formation of a strong crystal network with narrow capillaries. Due to this strong

network, crystal movement is not possible, causing the margarine to firm-up and become hard,

brittle and less plastic. The slow flow rate will also prolong the residence time of the product in the

tube coolers and in the pin worker, resulting in a prolonged contact with the refrigerated surfaces.

Because of the slow flow rate, the crystallization will already be completed in the tube cooler and

there will be no crystallization but only crystal breakdown in the pin worker. According to Miskandar

et al (2003), there was an increase in the consistency or hardness and a decrease of the amount of

solids during the storage of the margarine. This is due to the recrystallization of the network; a

transition of the crystal polymorph takes place from β’ to β crystals. (Miskandar et al, 2004 &

Miskandar et al, 2005)

When the emulsion flow rate is too high, the emulsion will not be sufficiently cooled due to the short

contact time with the cooled surfaces. The crystallization will occur in the pin worker and there will

be not much break down. At the end of the process, the amount of solids will be low, leading to a


weaker crystal network and a low consistency and promoting post-crystallization and hardening of

the margarine. During storage, the few nuclei will grow out to bigger aggregates with more

possibility for crystal mobility and enabling fast transition of the β’ to β crystals. (Miskandar et al,

2004 & Miskandar et al, 2005)

Speed of the pin worker

The crystallization continuous in the pin worker where also a physical breakdown of the crystals

takes place due to the movements of the pins, leading to an improved texture of the final product.

When the speed is too high, the crystal network will be broken down in small crystals. These small

crystals will lead to a very compact crystal structure that gives a hard margarine with a heavy

mouthfeel. (Miskandar et al, 2005)

2.1.5.2 Temperature

The temperature profile of the emulsion during crystallization in the process also has a big influence

on the final product. The product temperature will also change during the process because of the

release of latent heat of crystallization. The most crucial temperatures in the process are the

emulsion temperature in the beginning of the process and the scraped-surface tube cooler

temperature.

Emulsion temperature in the beginning of the process

The emulsion temperature will have the biggest influence on the crystallization rate. High emulsion

temperatures cause low crystallization rates because of a large difference between emulsion and

crystallization temperature resulting in a long induction time. No or little crystallization will take

place in the SSHE and the temperature of the product will be lower than for a lower emulsion

temperature as there is less release of latent heat of crystallization. A small temperature difference

will lead to crystallization in the SSHE, so there will be release of the latent heat of crystallization and

the product will have a higher temperature and a higher SFC after the SSHE. At high emulsion

temperatures, the product crystallizes in the pin worker. According to Miskandar et al (2002a), a

difference in emulsion temperature will lead. (Miskandar et al, 2002a & Miskandar et al, 2005)

Scraped-surface tube cooler temperature

Crystallization of the emulsion does not happen at the same time for the whole mass. The

crystallization will start at places where the temperature goes below the crystallization point. With a

fast cooling the crystals will be smaller and more uniform. At slow cooling, there is a slow

crystallization process. This lead to a decrease in solid fat content, in hardness and small crystals will


aggregate to larger ones. An emulsion that passes a tube cooler at lowest temperature will get the

greatest cooling and create more nuclei and crystals. This results in the highest SFC after passing the

tube cooler. These mass will also have the highest reduction of SFC in the pin worker because of the

breakdown of the crystal network and there will be no or least crystallization of the sample. High

cooling rates give raise to a high consistency and are desirable for hard margarines, low cooling rates

and thus lower consistency of the product, will be desirable for soft margarines. (Miskandar et al,

2002b & Miskandar et al, 2005)

An emulsion that passed through a tube cooler at low temperature will have at the end the highest

SFC. This means that there is a good crystal network; this will lower the mobility of the crystals and

also delay the transformation of β’ crystals in β crystals. At higher cooling temperatures the crystal

network will not be completely formed. The crystallization will go further during storage and will

favour the forming of β crystals. (Campos et al, 2002; Miskandar et al, 2002b & Miskandar et al,

2005)

2.1.5.3 Shear forces

During the production, the margarine undergoes large shear forces, especially in the SSHE and the

pin worker. Shear is desirable because it makes the product homogeneous and obtains the good

product qualities. For margarine, the shear will give consistency and stability to the product; it will

also decide the polymorphic form of the fat crystals. Shear will affect both the crystallization rate as

the crystal size. Shearing during the crystallization of palm oil will enhance the transformation of α

crystals into β’ crystals. At higher shear rates, the transformation will go faster. (PhD Veerle De Graef,

2009; De Graef et al, 2009; Narine et al 2004 & Miskandar et al, 2005) Shear has also an influence on

the water droplet size distribution of the margarine. The shell formation around the water droplets is

more pronounced and smaller crystals that are induced by shear can better adjust and adhere to the

water droplet surface (Vereecken, 2010)

Wrong processing conditions can lead to too much or too many shear and this will give an

unacceptable product. When a product is over stirred, a lot of small crystals will form. The structure

of the margarine will be too compact and reduces the mobility of the crystals. The product will be

brittle. When there is too little shear forces during the cooling, the most of the primary bonds will

stay intact and will undergo post hardening. This will lead also in a hard and brittle product. When

the crystallization occurs mostly in the SSHE, the margarine will have a good consistency and

spreadability. (De Graef et al, 2009 & Miskandar et al, 2005)


2.2 Palm oil and its fractions

Palm oil is derived from the flesh of the fruits of the oil palm Elaeis guineenses. The production

strongly increased the last thirty years and palm oil has overtaken soybean oil as the world’s leading

vegetable oil. Malaysia and Indonesia are the biggest producing countries of palm oil. The oil palm

has a high productivity: a hectare of mature oil palms produce between 4 and 6 tons of palm oil. The

use in Europe is growing for industrial and food purposes due to the low price, broad chemical

composition, suitability of fractionation and as alternative for partially hydrogenated fats which are a

source of trans fatty acids. Fractionation is the selective physical separation of the different

component groups. It can be used in the food industry as cooking oil, margarine, shortening and in

confectionary products. (Carter et al, 2007; De Graef, 2009; Chen et al, 2002; Dewettinck et al, 2010-

2011)

Palm oil is rich in palmitic (44%) and oleic acid (40%). It has a high oxidative stability at elevated

temperatures due to small amounts of polyunsaturated fatty acids and large amounts of natural

antioxidants, like beta-carotene (De Graef, 2009) a member of the vitamin E family, which also

causes the orange colour. Palm oil can be modified by fractionation, interesterification

(rearrangement of the fatty acids on the glycerol backbone), hydrogenation (reducing the amount of

unsaturated bonds on the fatty acids) and blending. It has a slow crystallization process. According to

Chong et al. (2002), the slow crystallization is due to the slow crystallization rates of POO and POP

TAGs together with some diacylglycerols.

Palm oil is suitable for fractionation because of its broad chemical composition. The fractions go from

very hard palm stearin with an iodine value below 10 to palm super olein with an iodine value of 72.

A fractionation process is shown in Figure 2.4. The different fractions are obtained by changing the

fractionation conditions. These fractions can also be used in a wide range of food applications.

The palm stearin is very useful as a source of fully natural hard fat component for the production of

margarines and shortenings. The palm olein has a low melting point. It blends easily with other

vegetable oils and it is often used as frying oil. Palm olein has good frying properties because of the

good resistance to oxidation. (De Graef, 2009; Njumbe Ediage, 2007)

The oil and fractions, especially palm stearin, can be used as alternatives for partially hydrogenated

fats. Partial hydrogenation leads to the formation of trans fatty acids which have negative health

implications. Alternatives to partially hydrogenated fats have to provide the same structure and

functionality as the original product with the trans fatty acids. Palm oil is frequently used in the


production of margarine and shortenings due to its high β’ stability and being semi-solid at room

temperature. (De Graef, 2009; Njumbe Ediage, 2007)

Figure 2.4: Multistage dry fractionation process of palm oil (PMF: palm mid fraction; IV: iodine value) (after Kellens et al, 2007)

2.3 Shea stearin

Shea stearin is obtained by fractionation of shea butter. Shea butter is produced out of the kernels of

the African plant Butyrospermum parkii. It is produced in different geographical regions of Africa

including Burkina Faso, Mali, Nigeria, and Uganda. Shea butter is used as a cocoa butter equivalent in

chocolate, margarines, cosmetics, soaps, and toiletries. It has antioxidant and anti-aging properties.

The stearin fraction is used as a cocoa butter equivalent (CBE). CBEs are vegetable fats which have

chemical and physical properties similar to cocoa butter. They are compatible with cocoa butter in

any proportions without causing significant softening or hardening effects (Kaphueakngam et al,

2009). Shea stearin can also be used as an alternative fat in the production of margarine with less

trans fatty acids (Dewettinck et al, 2010-201).

Materials and methods | 15

3 Materials and methods

3.1 Samples

3.1.1 Reference samples

Four different fat blends were made. The fat blends exist out of one hardstock component: shea

stearin or palm stearin and a diluting oil, palm olein IV 62. The fat blends were composed that way

that they contain the same SFC at specific temperatures. All four fat blends had a SFC of 35% after

24h. These SFC was chosen because of its relevance for bakery margarines. The working

temperatures were 15°C and 20°C because of their similarity with those encountered during the

process and the storage of bakery margarines. The composition of the different fat blends is shown

in Table 3.1. The palm olein and palm stearin were provided by Vandemoortele NV (Izegem,

Belgium). Shea stearin was provided by Fuji Oil Europe (Ghent, Belgium).

Table 3.1: Composition of the different reference samples (Vereecken, 2010)

Sample % Palm olein % Palm stearin % Shea stearin

Shst15 75,1 / 24,9

Shst20 56,5 / 43,5

Pst15 74,5 25,5 /

Pst20 50,1 49,9 /

3.1.2 Cake margarine based samples

In the third part of this research, tests were done to compare the pilot scale with the lab scale.

Therefore, two reference samples (Shst20 and Pst20), a cake margarine fat and cake margarine were

tested. The margarine fat and the fat phase of the margarine had the same composition and exist out

of 80% palm oil and 20% palm stearin. The composition of the margarine for 1kg was:

617,8g palm oil

154,4g palm stearin

198,7g water

1,546g emulsifier: distilled saturated monoacylglycerols based on hardened palm

0,367g citric acid

26,070g vegetable oils and fats


0,988g salt

0,154g aromas and colorants

Both palm oil, palm stearin and the emulsifier were provided by Vandemoortele NV (Izegem,

Belgium).

3.2 Chemical composition samples

3.2.1 Fatty acids

Sample: 10 droplets of liquid fat were dissolved in 2ml diethylether and 2ml of a 5%

KOH/methanol solution. The fat blend was shaken and had to react for 3min, no fat should

crystallize. 2ml demineralised water and 10ml heptane were added and the mixture was shaken.

The heptane layer was carefully decanted in another test tube. This layer was washed for two

times with 4ml demineralised water. The heptane layer was each time decanted in another test

tube. To dry the heptane phase a pinch of Na2SO4 was added. The GC vial was filled and 0.8-1µl

of the solution was injected using an autosampler.

Apparatus information: The determination of the fatty acids were carried out on a Varian 430 GC

(Middelburg, The Netherlands) provided with a split injector and FID detector. A fused silica

column BPX70 was used (length: 50m, internal diameter: 0,22mm, layer thickness: 0,25µm) with

a 70% cyanopropyl-polysilfenylene siloxane stationary phase. The carrier gas was helium. The

temperature of the injector, detector and oven were respectively 250°C, 260°C and 185°C.

Measurement: The peaks of the chromatogram were integrated and processed with the DGS

software.

3.2.2 TAGs

Sample: 2,5g of sample was dissolved in 10ml chloroform and 40ml iso-octane. There should be

no fat crystallize. The sample was thoroughly shaken to have a homogenous solution after which

a HPLC vial was filled. The injector volume was 10µl.

Apparatus information: The TAG separation was done on a Waters HPLC (Milford, Massachusetts,

USA) equipped with a 5micron Alltech Alltima HP reversed phase C18 high-loaded column

(250x4,6mm). The running solvent was a 65/35 mixture of acetone/acetonitrille.

Measurement: The peaks in the chromatogram were integrated and compared with the

chromatogram of a reference sample, palm oil.


3.2.3 SFC

Sample: 4ml of the sample was placed into glass tubes (diameter: 9,9mm, length: 150mm).

Apparatus information: The SFC was determined by pulsed NMR using a Bruker MQ20 Minispec

(Bruker optics, Ettlingen, Germany).

Measurements: The samples were put for one hour at 60°C to remove crystal memory and then

placed at 0°C for one hour. The SFC was measured in the range of 5 to 55°C with intervals of 5°C.

The samples had an incubation of 30 minutes at each temperature. The measurements were

done in triplicate.

3.3 Crystallization under shear: fundamental study

3.3.1 Oscillatory rheology

Sample: 30ml of the melted fat sample at 70°C.

Apparatus information: The measurements were done with a TA Instruments AR2000 control

stress rheometer (TA Instruments, Brussels, Belgium) using a starch pasting cell.

Measurement: The sample was put in the cup. The cooling jacket had a temperature of 70°C. The

following time-temperature profile was used:

o 10 min at 70°C to erase all crystal memory;

o Cooling at 10°C/min until the desired crystallization temperature (15°C or 20°C) is

reached;

o Oscillatory time sweep at the achieved crystallization temperature at a certain shear

rate (0 s-1, 75 s-1, 150 s-1, 300 s-1 or 500 s-1) for a defined time (15min, 30min or

1h);

o Keeping the sample at the crystallization temperature without shear until the

isothermal period is 2h.

Each sample was analyzed three times.

3.3.2 Rheo-NMR

Sample: 4ml of sample was placed into glass tubes of 10mm. The sample was sheared in an

external water bath (Julabo, Seelbach, Germany) using a glass shaft (5mm diameter) to avoid

interference with the NMR. The glass shaft was connected with a flexible to a mechanical stirrer.

The configuration is shown in Figure 3.1.


Figure 3.1: The configuration used to apply shear to the sample while it crystallizes in a water bath (after Vereecken, 2010)

Apparatus information: The SFC was determined by pulsed NMR using a 23,4 MHz Maran Ultra

pulsed field gradient NMR (Oxford Instruments, Oxfordshire, United Kingdom). The temperature

of the water bath was 15 or 20°C, depending on the temperature used for crystallization.

Measurements: Every two minutes, the NMR tube was disconnected from the stirrer and the SFC

was measured. This was done for 60 minutes and in triplicate.

3.4 Crystallization under shear: applied study

3.4.1 Rapid Viscosity Analyzer (RVA)

Sample: 30ml of the melted fat sample at 70°C.

Apparatus information: The crystallization was done with a RVA of Newport Scientific (Hamburg,

Germany) in disposable RVA-cells (both cans and rotors), as shown in Figure 3.2. These cells have

a similar geometry as the starch pasting cell of the rheometer. The RVA is attached to an external

water bath at 2°C necessary to cool the sample to the crystallization temperature.

Figure 3.2: RVA with corresponding disposable RVA-cell (after Vereecken, 2010)


Measurements: The sample was put in the can. The RVA had an initial temperature of 70°C. The

following time temperature profile was used:

o 1 min at 70°C;

o Cooling at 10°C/min until the desired crystallization temperature was reached;

o Keeping the sample at the crystallization temperature for 15min.

Every step was executed at a rotational speed of 160rpm.

3.4.2 Controlled temperature shearing unit (CTSU)

Sample: 1kg of melted sample was placed in the bowl of the CTSU.

Apparatus information: The samples were crystallized in a Herbst HR-S3 Tempering unit (Herbst

Maschinenfabrik GmbH, Buxtehude, Germany) connected to a Huber Thermostat (Peter Huber

Kältemaschinenbau GmbH, Offenburg, Germany). In addition a countercurrent flow heat

exchanger is provided to obtain faster cooling. The tempering unit consists out of a bowl (4L)

with a double wall and a temperature control. The stirrer carries out homogenization and

crystallization under shear of the sample during cooling. There is also a scraper to scrape off the

crystallized product from the cooled wall (see Figure 3.3).

Figure 3.3: The stirrer and scraping device of the CTSU (left) and the entire CTSU (right)

Measurements: The bowl was placed at 70°C and the sample was sheared at a specific shear rate.

The procedure was started when the temperature of the sample reached 70°C (registered by the

CTSU). The following time temperature profile was used:

o 5min at 70°C;

o Cooling at ±10°C/min until the desired crystallization temperature was reached, the

cooling rate could not be controlled;

o Keeping the sample at the crystallization temperature for a specific time.


3.4.3 TNO cell

Sample: After the RVA treatment, the sample was immediately brought in the cylinder of the

TNO cell.

Apparatus information: The experiments were carried out using a TA.XT2 Texture analyzer

(Stable Micro Systems, Surrey, UK) that was connected to the extrusion or TNO cell. The

extrusion cell consists of a cylinder with a diameter of 3cm and a height of 85mm. In the cylinder

fits the probe which is made of a stick with a disk with 6 holes.

Measurements: After filling, the probe is placed on the sample and the cylinder is closed. The

probe moves through the sample up and down and this for 100 or 200 times. The temperature

can be kept constant because the cell is placed in a bath filled with water at a controlled

temperature.

3.4.4 Pilot Vandemoortele

The different fat blends and margarine were prepared by using a pilot installation (Gerstenberg

Schröder A/S, Brøndby, Denmark) located at Vandemoortele NV (Izegem, Belgium). The pilot

installation consists of the following configuration: a high pressure pump (150rpm), a pasteurization

unit, four cooling cylinders (500rpm), a pin worker (360rpm) and a resting tube (only used for the

margarine production). The cooling temperature of the first two cooling cylinders was -12°C for the

fat blends and -5°C for the margarine production. The last two cooling cylinders had a cooling

temperature of -5°C. The cylinders are cooled with freon.

3.4.5 Pilot UGent

The different fat blends and margarine were prepared by using a Schröder universal Kombinator type

VUK-01/60-400 (Gerstenbeg Schröder A/S, Denmark). The pilot installation consists of a plunger

pomp (3 plungers), a cooling cylinder (500rpm) with a cooling between -7°C and -9°C and a pin

worker (625rpm).

3.5 Evaluation of the crystallized fat blends and cake margarine as

function of storage time

3.5.1 SFC

Sample: The sample was placed in a glass tube with diameter of 10mm.

Apparatus information: The SFC was determined by pulsed NMR using a Maran Ultra NMR

(Oxford Instruments, Oxfordshire, United Kingdom), the temperature in the probe could be

controlled by an external water bath.


Measurements: The glass tube was placed in the probe and the SFC was measured, four

measurements of each sample were measured The temperature of the external water bath was

equal to the storage temperature of the samples (15°C or 20°C).

3.5.2 Hardness

Sample: After the process, the process was poured in a plastic cylindrical recipient of 100ml or in

tubs of 250ml.

Apparatus information: The hardness was measured with a Texture Analyzer TA 500 and a TAplus

Texture analyzer (Lloyd Instruments, Hampshire, United Kingdom) with a 500N load cell and

TA.XT2 Texture analyzer (Stable Micro Systems, Surrey, UK) with a 5kg load cell, both with a

conical probe with an angle of 45°.

Measurements: The probe descends at 0,2mm/s and goes down for 10mm with a trigger of

0,08N. The hardness is expressed as the maximum load (N) during the 10mm of penetration. Five

repetitions were executed.

3.5.3 Microscopy

Sample: A small amount of two different samples was placed on a glass slide, covered with a

cover slip and an equal pressure was applied on both samples with another slide.

Apparatus information: The microstructure was evaluated by polarized light microscopy with a

Leitz Dialux 22EB microscope (Leitz Dialux, Leica, Wetzlar, Germany). This microscope was

equipped with a quarter-wavelength plate (quarter-lambda plate), which was placed between

the sample and the analyzer.

Measurements: The images were taken with a Leica DFC 280 Camera (Leica, Wetzlar, Germany)

at a magnification of 100x.

3.5.4 Water droplet size

Sample: The samples were placed in a Bruker AR glass tube (diameter: 10mm length: 180mm)

and placed in a water bath of 5°C.

Apparatus information: The water droplet size distribution was measured with a Bruker NMR

Minispec MQ20 (Bruker optics, Ettlingen, Germany). The probe had a temperature of 5°C.

Measurements: The D3,3 (=volume weighed geometric mean diameter), log(sigma)(=standard

deviation) and the 97,5% value were measured.


3.6 Sponge cakes

3.6.1 Preparation of the sponge cakes

The ingredients of the classic 4/4 sponge cakes were: 300g wheat flour (Gents Bakkershuis, Ghent,

Belgium), 13g baking powder (Gents Bakkershuis, Ghent, Belgium), 300g liquid whole egg

(Lodewijckx, Veerle-Laakdal, Belgium), 300g sugar (Gents Bakkershuis, Ghent, Belgium) and 300g

margarine. The sponge cake batters were prepared with a Kenwood Major kneader (Kenwood,

Vilvoorde, Belgium) starting with the kneading of the margarine. The cakes were baked by placing

the batters during 45 minutes in an oven at 175°C.

3.6.2 Photographic images of the cake volumes

Sample: Slices of a thickness of one cm were taken of the cake.

Apparatus information: The photographs were taken using a Sony DSLR-A390 camera (Sony

Corporation, Tokyo, Japan).

3.6.3 Hardness

Sample: Slices of two cm were taken of each cake.

Apparatus information: The hardness was measured with a TAplus Texture analyzer (Lloyd

Instruments, Hampshire, United Kingdom) with a 500N load cell with a cylindrical probe with a

diameter of 13mm (CNS Farnell, Hertfordshire, United Kingdom).

Measurements: The probe descends at 10mm/min and goes down for 10mm with a trigger of

0,2N. The hardness is expressed as the maximum load (N) during the 10mm of penetration. Ten

repetitions were performed on each sample.

3.7 Statistical analyses

The statistical analyses were executed with the program SPSS 15.0 (Illinois, USA). The measurements

were statistically compared with a One Way Anova test. First, the Levene test was done to test the

hypothesis of equal variances. If the hypothesis was accepted, a Tukey test was used to check

significant differences on a 95% significance level. If the hypothesis was rejected, a Dunnett’s T3 was

used.

Results and discussion | 23

4 Results and discussion

The aim of this research was to develop a method to produce margarine on lab scale with similar

properties as the product on pilot scale. From the schematic overview in Figure 4.1, it can be seen

that the research was divided in three main parts; the first part was the characterization of the fat

blends and a more fundamental research of fat crystallization under shear. In the second part the

aim was to find a suitable method on lab scale and in the last part, the results of the lab scale with

the controlled temperature shearing unit (CTSU), as selected in the previous part, were compared

with these of the pilot of Vandemoortele (PilotVDM) and the pilot of FTE (PilotFTE). The research was

in cooperation with Vandemoortele NV.

Figure 4.1: The schematic overview of the research

4.1 Part 1: Crystallization under shear: fundamental study

4.1.1 Characterization of the fat blends

The fatty acid profile, the triacylglycerol (TAG) composition and the non-isothermal SFC were studied

for five selected samples. The four reference samples (Shst15, Shst20, Pst15 and Pst20) contained of

shea stearin (Shst) or palm stearin (Pst) with palm olein as diluting oil (see Table 4.1). The

composition of these samples was as such that the SFC equals 35% after 24 hours at 15°C (Shst15 and

Pst15) or 20°C (Shst20 and Pst20) (Vereecken, 2010). Palm stearin and shea stearin were used as an

alternative for some unhealthy fats, like hydrogenated fats that can contain a lot of trans

Part 1

• Chemical characterization of the fat blends

• Fundamental research

• Rheo-NMR and oscillatory rheology

Part 2

• Search alternative for production on pilot scale:

• RVA (+ post treatment)

• CTSU: influence of the rotational speed - length of the shearing phase

Part 3

• Comparison of the different scales with fat blends and margarine

• CTSU vs PilotFTE

• CTSU vs PilotVDM


unsaturated fatty acids, in the margarine production. The cake margarine based samples contained

palm oil and palm stearin (see Table 4.1). The composition was based on a standard cake margarine

fat.

Table 4.1: Composition of the fat blends

Shst15 75,1% palm olein + 24,9% shea stearin

Shst20 56,5% palm olein + 43,5% shea stearin

Pst15 74,5% palm olein + 25,5% palm stearin

Pst20 50,1% palm olein + 49,9% palm stearin

Margarine fat 80% palm oil + 20% palm stearin

4.1.1.1 Chemical composition

Table 4.2 presents the fatty acid profile of the different fat blends, executed by gas chromatography.

The major fatty acids in both the fat blends with shea stearin, palm stearin and margarine fat were

palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2cis) but at

different ratios. The amount of saturated and unsaturated fatty acids was similar (see last line of

Table 4.2). All the fat blends contained low amounts of trans fatty acids (<1%).

Table 4.2: Fatty acid (%) profile of the different fat blends

Shst15 Shst20 Pst15 Pst20 Margfat

C16:0 31,13 21,00 45,27 50,06 46,72

C18:0 17,65 26,99 4,27 4,51 4,27

C18:1cis 40,16 40,87 39,02 34,96 37,53

C18:2cis 7,85 8,37 8,49 7,52 8,65

Others* 3,21 2,77 2,95 2,95 2,83

Unsaturated 49,04 50,66 48,54 43,42 47,01

*sum of the fatty acids with amounts < 1%

Table 4.3 gives the TAG composition of both the reference and cake margarine based samples. Shea

stearin is a source of SOS and this TAG was thus also a major component of the fat blends with shea

stearin. In these fat blends, there was also a high amount of POP and POO/SOL, the amount of

symmetric TAGs present was high. Symmetric TAGs are known to have a rather slow crystallization

rate (Timms, 2003).

Palm stearin is a source of PPP triacylglycerol and this TAG was an important component of the fat

blends with palm stearin and the margarine fat. Besides PPP, the fat blends also contained large


amounts of POP and POO/SOL. PPP is a seeding agent and will have an effect on symmetric

triacylglycerols like POP. PPP promotes crystallization and will cocrystallize with POP; meanwhile POP

will reduce the crystallization rate (Vereecken, 2010 and Smith et al, 2005).

In the case of margarine fat, the high amounts of palm oil and in the case of the other fat blends, the

high amounts of palm olein, were responsible for the high amount of POO/SOL. For the other blends,

the high amounts of palm olein were responsible

Table 4.3: TAG (%) composition of the different fat blends

TAG Shst15 Shst20 Pst15 Pst20 Margfat

PLL 1,60 1,67 1,98 1,59 2,00

LOO 1,63 1,70 1,86 1,70 1,86

PLO/SLL 8,28 8,59 9,56 8,33 9,30

PPL 7,74 5,72 9,65 8,58 9,04

OOO 3,79 3,80 4,26 4,50 4,18

POO/SOL 19,39 19,40 22,89 19,55 21,61

PPO/POP/PSL 22,33 11,15 29,85 29,82 28,23

PPP 1,18 0,22 7,43 13,16 9,93

SOO 3,53 5,25 2,53 2,28 2,57

PSO 7,50 7,21 5,27 5,33 5,05

PPS 0,25 ** 1,43 2,64 2,10

SOS 18,73 32,43 0,65 0,62 1,02

Others* 4,05 2,86 2,64 1,90 3,11

*sum of the TAGs with amounts < 1% **no detectable amounts

4.1.1.2 Non-isothermal SFC

Figure 4.2 shows the SFC-profile of the different fat blends. The fat blends with shea stearin melt

more quickly than the fat blends with palm stearin, which contained a higher amount of saturated

fatty acids (see Table 4.2). Shst15 had a melting point around 35°C, which was slightly lower than the

melting point of Shst20 that was about 40°C. This difference was due to the higher amount of PPP in

Shst20. The fat blend Pst20 had the highest melting point, namely between 50°C and 55°C, followed

by margarine fat (around 50°C) and then Pst15 (between 45°C and 50°C). The higher the amounts of

PPP and saturated fatty acids and the lower the amounts of POO/SOL, the higher the melting point of

these fat blends (see Table 4.2 and Table 4.3).


Figure 4.2: SFC as a function of temperature (°C) for the different fat blends

4.1.2 Fundamental study of crystallization under shear

In margarine production the applied shear is an important process parameter that has a significant

effect on the structure development. It is thus of paramount importance to gain insight in the

crystallization behaviour of fat systems under shear. The effect of shear on the crystallization of fat

blends will be studied by rheo-NMR and oscillatory rheology.

4.1.2.1 Rheo-NMR

With the rheo-NMR technique, the SFC was studied during one hour of shear and also compared with

the SFC without shear. This technique was applied to the four reference samples at their respective

temperatures and the results are shown in Figure 4.3. The first data point had a negative isothermal

time because the sample was cooled from 70°C to the crystallization temperature (15°C or 20°C)

during the first 2 minutes.

In Figure 4.3(a), the SFC profile of the fat blends with shea stearin is shown with and without shear.

For the fat blends Shst20 there was a fast increase of SFC to remain constant afterwards. In the

absence of shear, it took more time to reach the maximum SFC of 6%. So the crystallization at 20°C

stayed constant after 2 minutes when the fat blend underwent shear and after 4min for the sample

without shear. The crystallization process was enhanced when shear was applied (De Graef, 2009).

For the sheared samples the SFC plateau showed some fluctuations. This can be explained as

continuous crystallization and dissolving of the sample due to shearing (Vereecken, 2010). Although

the SFC seemed to have reached an equilibrium, the crystallization process still proceeded. The slow

crystallization rate is due to the fact that the fat blends were designed to reach 35% SFC after 24h of

crystallization. For the fat blends crystallized at 15°C, bigger differences were observed between the

sample with shear and the one without shear. The curve of fat blend Shst15 without shear showed


the same shape as the ones crystallized at 20°C. The crystallization process was here again so slow

that it seems that the crystallization reached a maximum. The fat blend Shst15 with shear had a

different shape. After one hour, the crystallization of the sample with shear was still increasing. The

crystallization rate of this sample was the highest of the four samples because it contained less

symmetric TAGs and shear enhanced the crystallization. Both samples had at the end a higher SFC

than the samples crystallized at 20°C due to a lower crystallization temperature.

In the Figure 4.3(b), the crystallization during one hour of the fat blends with palm stearin is shown,

both with and without shear. The same procedure was followed, thus the crystallization temperature

of Pst15 was 15°C and for Pst20, 20°C. The curves ended all at similar SFC, namely 35%. The

crystallization proceeded very fast. After less than one hour the expected SFC, normally after an

equilibrium time of 24h, was already achieved. This was due to the high amount of PPP in both

samples. PPP is a seeding agent and will accelerate the crystallization (Vereecken, 2010 and Smith et

al, 2005). Fat blend Pst20 reached faster the equilibrium than fat blend Pst15 which was again due to

the higher amount of PPP in fat blend Pst20 (see Table 4.3). As for the samples with shea stearin, the

curves of the samples with shear were slightly steeper in the beginning and sooner reached the

equilibrium value than the samples without shear. That can again be explained by the fact that

crystallization was enhanced by shear.

(a) (b)

Figure 4.3: Rheo-NMR of the fat blends with (a) shea stearin and (b) palm stearin


The curves of the fat blends with shea stearin did not reach a similar value as in the case of the palm

stearin blends (see Figure 4.3(b)) and the SFC was also much smaller than 35%. The crystallisation

rate was thus much slower than these of the fat blends with palm stearin. This was due to the large

amount of symmetric triacylglycerols, like SOS and POP and the rather small amounts of PPP (see

Table 4.3). The large amount of SOS is typically for shea stearin, this was the reason why Shst20, with

more shea stearin, had a lower SFC than Shst15. (Vereecken, 2010)

4.1.2.2 Oscillatory rheology

The crystallization under shear was also studied with rheology. Four shear rates (75s-1-150s-1-300s-1-

500s-1) were applied for 4 shear times (0min-15min-30min-60min) after which crystallization under

static conditions was further monitored up to 120min isothermal time. As a reference, the

crystallization without shear was also recorded. Although measurements were executed in triplicate,

the plotted rheological results represent one exemplary curve as very little variation was observed

between the repetitions.

The complex modulus (|G*|) in function of the isothermal time for the different fat blends are shown

for crystallization without shear in Figure 4.4. All the fat blends showed a curve in two steps. These

two steps could be related on the one hand to the polymorphic transition of α crystals in the first

step and a transformation in β’ crystals in the second step or on the other hand to fractionated

crystallization. After two hours the curves reached a similar end value, except for the fat blend

Shst15 where |G*| was still increasing. The |G*| of the samples with palm stearin started to increase

before one minute isothermal time. Pst20 increased slightly faster and reached fast the equilibrium

value. The more PPP, thus the more palm stearin present, the faster the product will crystallize and

the |G*| will increase sooner. The samples with shea stearin started to increase after 2 and 3

minutes isothermal time for respectively Shst20 and Shst15. These samples thus crystallized slower

and the end point was reached later. This slow crystallization rate is due to the high amounts of

symmetric triacylglycerols like SOS and the low amounts of PPP; which could also be concluded from

the rheo-NMR results.


Figure 4.4: Complex modulus (|G*|) as a function of isothermal time for all fat blends for crystallization without shear

The apparent viscosity, recorded during the shearing step at isothermal conditions, is shown as a

function of the isothermal time in Figure 4.5. Shear was applied for 15, 30 and 60 minutes at the four

shear rates. For all samples, an effect of shear rate on the initial apparent viscosity could be

observed, which was due to the fact that shear was already applied during the cooling (De Graef,

2009). The initial apparent viscosity at 75s-1 was the lowest, followed by 150s-1 and the highest initial

apparent viscosity was at the highest shear rates, namely 300s-1 and 500s-1. Upon later isothermal

times the apparent viscosity increased substantially at all shear rates. The increase was due to the

formation of primary crystals but also due to the aggregation into a crystal network (De Graef, 2009).

All fat blends showed an earlier increase in apparent viscosity at higher shear rates due to a faster

crystallization. However, the higher the shear rate, the smaller the increase in apparent viscosity,

resulting in a lower equilibrium value for the samples at higher shear rates. No large differences were

observed for shearing at 300s-1 compared to shearing at 500s1. According to the study of Tarabukina

et al (2009), 300s-1 seems to be a critical shear rate: from 300s-1 onward aggregation of the crystals is

no longer possible as the contact time between the colliding entities is too short to enable

aggregation. The same effect will happen with a shear rate of 500s-1 and that was why the curves

were very similar. The apparent viscosity increased in two steps for every fat blend, indicated by

numbers in Figure 4.5. The parts 2 and 4 represent the two increases and the parts 1, 3 and 5 show

the apparent viscosity plateaus.

For the fat blends crystallized at 15°C (Figure 4.5(a) for Shst15 and Figure 4.5(b) for Pst15) the two

steps were clearly defined. Looking at the different isothermal periods, it can be seen that after


15min only the first increase (2) in apparent viscosity had occurred. Consequently, a lower apparent

viscosity value was recorded after 15 min compared to longer shearing times. After 30min the

second increase (4) was just finished and the apparent viscosity was only slightly lower than after

60min. Between 30min and 60min (5) the apparent viscosity was still increasing but not as strong as

in the second step (4). The final apparent viscosity was the highest for the lowest shear rate, which is

due to the fact that shear does not only enhance the primary crystallization but also influence the

microstructural development of the fat structure. The apparent viscosity was not only influenced by

the amount of solids but also by the crystal size distribution and the crystal interactions (De Graef,

2009 and Kellens et al, 2007). The higher the shear rate, the more break down of aggregates will take

place.

(a) (b)

(c) (d) Figure 4.5: Apparent viscosity recorded during the shearing step in function of the isothermal time of (a)

Shst15, (b) Pst15 (c), Shst20 and (d) Pst20


For the fat blends Shst20 (Figure 4.5(c)) and Pst20 (Figure 4.5(d)) crystallized at 20°C, the two steps

were not well distinguished and the plateau between the steps (3) was not clearly visible. The final

apparent viscosity was also lower than the samples crystallized at 15°C. This can be explained by a

lower driving force for crystallization at higher temperatures. For the shea stearin blends, it could

also be due to the amounts of SOS or PPP; the sample Shst15 had a lower amount of SOS and higher

amount of PPP. As concluded before, Shst15 will crystallize faster and have a higher apparent

viscosity. Subsequent to the second apparent viscosity increase (4) of the samples crystallized at

20°C, a small decrease could be observed, indicating some structural breakdown of the primary

network due to the shear forces (De Graef, 2009). As a constant apparent viscosity was reached

before 15min, all the different shearing periods will result in similar final apparent viscosity values.

Following the sheared crystallization, monitored in terms of apparent viscosity, crystallization

proceeded under static conditions. During this static crystallization the |G*| was measured in

function of the isothermal time. The results of the fat blends with shea stearin are shown in Figure

4.6. Figure 4.6(a) and Figure 4.6(d) represent the results after 15min of shear for respectively the fat

blends Shst15 and Shst20. The shape of the curves was similar, but the increase goes on earlier and

steeper for Shst15, which was due to the lower amount of symmetric triacylglycerols in this fat blend.

As already mentioned, symmetric triacylglycerols will slow the crystallization rate. The higher the

shear rate, the steeper the increase will be. This could be explained by the shear rate that enhanced

the crystallization rate. For Shst15, shearing at 300s-1 or 500s-1 did not affect the |G*| values at the

end of the isothermal period. Both shear rates are high and as mentioned before, aggregation is not

possible during shearing. After shearing, the crystallisation and network forming continued similar.

For both blends, similar final |G*| were observed regardless of shear rates applied in the first part of

the crystallization process.

For graph (b), (c), (e) and (f) in Figure 4.6, the same trend could be observed: a steep increase

followed by a constant |G*|. After the period of shear, these samples already underwent a second

increase in apparent viscosity which was not the case after 15min of shearing, as seen in Figure 4.5.

The initial |G*| after 30min and 60min of shear was ten times higher than after 15min of shear,

more crystals or a stronger network was formed resulting in a higher |G*|. At the end of the

isothermal period, the |G*| reached the same value.

Although at the end of shear step, the samples crystallized at 15°C showed a higher apparent

viscosity compared to crystallization at 20°C, their initial complex modulus values were lower.


Figure 4.6: |G*| in function of the isothermal time of Shst15(d, e, f) and Shst20(a, b, c) recorded after a shear step of 15min (a, d), 30min (b, e) and 60min (c, f)

Figure 4.7 shows the crystallization under static conditions of the fat blends with palm stearin after a

shear step. Different lengths of this shear step did not result in large differences in initial |G*|,

although the final apparent viscosity after 15min of shear was much lower than after 30 and 60

minutes. The samples crystallized at 15°C and 20°C did also not show big differences in initial |G*|,

although the final apparent viscosity differed a lot at the step with shear. The apparent viscosity of

the samples at 15°C was higher than these at 20°C (Figure 4.5) but this translated into differences in

the initial |G*|. The |G*| was increasing in time, but more gradually than the samples with shea


stearin. It can also be observed that the higher the shear rate in the period of shear, the higher the

final apparent viscosity will be.

Figure 4.7(a), (b) and (c) show the samples crystallized at 15°C after respectively 15, 30 and 60

minutes of shear. After 15min of shear, a clear difference could be observed between the two

highest and two lowest shear rates. The samples of 75s-1 and 150s-1 started at low |G*|, increased

first fast and around 25min the slope was decreasing. For the two higher shear rates the |G*| started

higher but the first increase was not as steep. At the end, the |G*| all reached a similar value. After

30 and 60 minutes of shear the increase was more gradually and the two steps are not as visible. The

longer the period of shear, the more the curve of 150s-1 shifted to the curves of 300 and 500s-1. The

samples of 150, 300 and 500s-1 still achieved a similar end value, whereas the curve of 75s-1 ended

lower with longer periods of shear. This could be explained by the shorter time to crystallize as the

period of shear was longer, thus less crystallization has taken place, resulting in a lower |G*|.

For crystallization at 20°C (Figure 4.7(d), (e), (f)), the difference between the two highest and the two

lowest shear rates was also clearly visible. The shape of the curves was different of the samples

crystallized at 15°C. In the first part, the increase was not as steep. For the samples sheared at 75s-1

and 150s-1 for 15min and at 150s-1 for 30min a steep increase of the |G*| occurred after 90min. The

other curves did not show this second increase. After 15min of shearing the two highest shear rates

reached a similar value and the two lowest went to one. At longer times of shear, the two highest

shear rates still went to a similar value but the two lowest shear rates lie further apart.

The curves of the shea stearin and palm stearin did show a lot of differences, both the shape, begin

and final |G*| values differed between the two samples. At the end of the isothermal period, the

samples with shea stearin reached an equilibrium which was not observed for the palm stearin

blends. These blends were still increasing at the end, although the crystallization rate of the palm

stearin would be expected to be higher than for the shea stearin blends due to the high amount of

PPP in the palm stearin blend.


Figure 4.7: |G*| in function of the isothermal time of Pst15 (d, e, f) and Pst20 (a, b, c) recorded after a shear step of 15min (a ,d), 30min (b,e) and 60min (c,f)


4.2 Part 2: Crystallization under shear: applied study

The first objective was to find a suitable method to produce margarine on a lab scale as alternative for

the production on pilot scale. The first applied technique was the RVA and the RVA with a post-

treatment, this part was a continuation of the PhD of Jeroen Vereecken (2010). The second technique

that was used, was the controlled temperature shearing unit (CTSU).

4.2.1 Rapid Viscosity Analyzer (RVA)

The RVA can crystallize the fat blends under shear. Only 30ml of products is necessary instead of 20kg

on the PilotFTE or 70kg on the PilotVDM. The RVA had a similar geometry as the starch paste cell of the

rheometer; it also measures the apparent viscosity. In practice, the RVA is mostly used to investigate

the gelatinization.

The samples were crystallized at 15°c or 20°C with a shear rate of 160rpm or 75 s-1 for 15min, after that

the rotor is taken out and the can with the sample was stored under static conditions at the

crystallization temperature for two weeks. The sample was analyzed by NMR to measure SFC, Texture

analyzer to measure hardness and the appearance of grains was visually studied after one day, one

week and two weeks. The used time-temperature profile is shown in Figure 4.8.

Figure 4.8: Time-temperature profile used for the crystallization of the samples at 15°C under shear (after Vereecken, 2010)

The main disadvantage of the RVA is that only one rotational speed can be used. A long isothermal

crystallization period was not possible because at the end of the experiment, the rotor had to be

removed without damaging the fat structure. When the state of crystallization is too far, the product

will be too hard and the rotor cannot be taken out.

The results of the experiments were similar as in the one of the PhD of Jeroen Vereecken (2010). The

fat blends with shea stearin showed already grains after one day of storage. The fat blends with palm


stearin showed no grains after two weeks of storage. To have more crystallization during the process, a

post-treatment was used after the procedure of the RVA.

4.2.2 RVA followed with a post treatment

The RVA can be compared with a cooling step from the margarine production process and the TNO

extrusion cell with a post treatment in the pilot process. The TNO cell will give a similar treatment to

the samples as a pin worker. The extrusion cell consists of a cylinder; in this cylinder a stick with a disk

of 6 holes can be fitted. The sample, crystallized in the RVA, was brought as fast as possible in the

cylinder and the measurement in the TNO was started by moving the probe up and down for 100 or

200 times.

This procedure was carried out for the fat blend Shst20. Immediately after the whole procedure the

sample was taken out of the cylinder and there were clearly big and hard grains visible. The TNO

treatment accelerated the formation of the big grains. As seen in the RVA, the fat blends with shea

stearin tending to form β crystals during the storage. The crystallization of the β polymorph was

enhanced by the TNO cell that applied shear on the product. This method was not further developed.

4.2.3 Controlled Temperature Shearing Unit (CTSU)

A second alternative for the pilot production was the CTSU. The CTSU is normally used to temper

chocolate, but can also be used to crystallize fat and margarine samples under shear. The CTSU can

handle a range of rotational speeds of 0 rpm to 115 rpm and a big advantage is the possibility to stir

much longer than the RVA. For every batch, 1kg of sample was used; this is more than with the RVA

but still very small in comparison with the pilot productions.

4.2.4 Comparison of RVA and CTSU

To compare the samples, the dimensions of the devices should be considered. The tip speed gives an

indication of the shear forces. To compare the results, the procedure of the crystallization and the

same tip speed of the RVA were used on the CTSU. The rotational speed of the CTSU was calculated by

Equation 1.

Equation 1: (a) general formula; (b) tip speed of the RVA; (c) rotational speed of the CTSU

(

) ( )

( )

( )

(

)

( )

( )

⁄ ( )


Table 4.4 shows the comparison of the RVA and CTSU technique.

Table 4.4: Comparison of the RVA and the CTSU technique

RVA CTSU

30ml of sample 1l of sample

1 rotational speed: 160rmp Range of rotational speeds: 0-115rpm

Short period of crystallization under shear (15min) Long period of crystallization under shear possible

(2h)

Fast cooling: 10°C/min Fast cooling: 10°C/min

In the following tests, it was chosen to only discuss the fat blend Shst20 because it was most sensible

to the formation of grains and this was the most important problem that has to be avoided in the

margarine production. For every part, the hardness, SFC and the appearance of grains were studied

after one hour, one day, one week and two weeks of storage.

4.2.5 CTSU with similar conditions of the RVA

This part will compare the results of the RVA and the CTSU, executed with the same procedure (see

Material and methods, 3.4.1 and 3.4.2) and the same tip speed. The results are shown in Figure 4.9.

The difference in SFC between the RVA and CTSU technique were smaller than the difference in the

hardness. After one hour the SFC of the RVA was very low (lower than 10%) so during the RVA

treatment, not much sample was crystallized. This was due to the slow crystallization rate of the fat

blend by the high amounts of the symmetric triacylglycerol SOS (see before). After one day the SFC had

increased to 35%. This was also a control to see if the fat blends were made correct because they were

composed to have a SFC of 35% after 24h. After one day, one week and two weeks, the SFC increased

slightly but no differences were observed between the two techniques.

After one hour, the hardness of both techniques was rather low; no crystal network was formed yet.

After one day the hardness had increased especially for the sample produced with the CTSU. The

increase of the hardness with the RVA was not as big. After one and two weeks of storage, the

hardness continued to rise for the sample with the CTSU, although there was no difference in SFC. This

can be explained by sintering of the fat crystal network during post crystallization and this will lead to a

harder fat crystal network. Sintering is the formation of solid bridges between fat crystals and is

promoted by mismatches in the crystal network and by a more heterogeneous composition (Johansson


and Bergenstahl, 1995). In this case, the sample had a heterogeneous composition because the fat

blend consisted of approximately 50% of shea stearin and 50% of palm olein. In contrast, the hardness

of the RVA decreased in time thus the difference between the two hardness measurements became

bigger when the samples were stored longer. During the storage, sandiness appeared for both

samples, after one day. In the sample of the CTSU, the sandiness still appeared after one and two

weeks but in the sample with the RVA, a lot of big and hard grains appeared and their amount

increased in time. Vereecken (2010) identified these grains as fat crystals in β polymorph. This could

explain the decrease of the hardness in the samples of the RVA. The hard grains were embedded in a

soft matrix. It will be the hardness of the soft matrix that was measured instead of the hardness of the

grains. The hardness was thus underestimated.

Figure 4.9: Comparison RVA and CTSU @ 51rpm on fat blend Shst20 (NG=no grains, SA=sandiness, BG=big grains)

For the fat blend Shst15, there was a similar trend in both hardness and SFC, but the hardness was

more than two times higher. The grains formed after one week and two weeks were smaller with the

RVA technique and no grains were observed with the CTSU method. The fat blends with palm stearin

showed also the same trend in hardness. After one hour the SFC was already higher than 25%, many

crystals were formed during the treatment. This was due to the high amounts of PPP. As mentioned

before PPP is a seeding agent and it provides a fast crystallization. There was also no appearance of

grains during storage, which was due to the high amounts of palmitic acid in these fat blends which

stabilize the β’ polymorph.


4.2.6 CTSU - influence of the rotational speed

During storage at static conditions, the crystals have more time to form a regular crystal network and

this will favour the formation of β crystals and thus the formation of grains (Ghotra et al, 2002).To

avoid post crystallization, the crystallization had to be enhanced during the process by increasing the

shear forces. Higher shear forces will enhance the primary crystallization and influence the crystal

network (De Graef, 2009). This can be done by increasing the rotational speed. The rotational speeds

that were used to compare are 51 rpm, the same speed as before, and 115 rpm, which is the maximal

rotational speed of the CTSU. The highest rotational speed had a clear effect on the hardness that was

about three times higher than at the lower speeds, as seen in Figure 4.10. Especially after one hour,

there was a large increase of the hardness when higher speeds were applied. The crystal network was

already formed in the CTSU, which was not the case at 51 rpm. There was still a formation of some

grains at higher speeds, but the sandy feeling appeared after one week instead of after one day, like

the case of lower rotational speeds. The different rotational speeds had only a small influence on the

SFC. During the storage, sintering occurred and this will not change the SFC.

Figure 4.10: Comparison CTSU @ 51rpm and @ 115rpm on fat blend Shst20 (NG=no grains, SA=sandiness)

4.2.7 CTSU – influence of the length of the shearing phase

Another possibility to have a more completed crystallization during the process was increasing the

shear time so less post-crystallization will occur. From the oscillatory rheology (see 4.1.2.2, Figure 4.5),

it was seen that the crystallization was not completed after 15min of shear. The apparent viscosity of

the isothermal shear step at 15°C was not at the maximum after 15min and the second step had not

yet occurred. It was only after 30min that the apparent viscosity reached the maximum. Next to 15min


of shear, as in the previous parts, a shearing time of 30min, 1h and 2h was studied. The results of the

fat blend Shst20 is shown in Figure 4.11.

It can be concluded that the hardness decreased when longer shear times were used. The SFC did not

follow this trend and was mostly the same for the different shear times. This could be explained by

breakdown of the fat crystal structure when shearing longer. Another possibility of the lower hardness

is the intake of air bubbles during the shearing. The CTSU has a headspace with a volume as big as the

volume of the sample. During stirring, air can go from the headspace in the sample and air bubbles are

then retained by the crystal network.

The appearance of grains was also investigated. In the previous parts, it was seen that this was

especially a problem at fat blend Shst20. After already 30min of shearing, there was still no appearance

of graininess after 2 weeks of storage for this fat blend. Also in the other samples, there was no

appearance of grains.

Figure 4.11: Shst20 - longer period of shear (NG=no grains, SA=sandiness)

Both the RVA and the RVA with the TNO cell were not suitable to make a product on lab scale that is

similar the pilot scale; during the storage, grains appeared in the products of the shea stearin blend.

The second technique was the CTSU. The procedure was optimized by using higher shear rates and

longer shear times which resulted in samples without grains in the shea stearin blend during storage.

This technique was further used in part 3.


4.3 Part 3: Lab scale versus pilot scale

Up to now, only the pilot scale can be used to produce margarine products similar to industrial scale

but these tests need relatively large amount of fat ingredients and time. To do more tests with less

sample in less time, a lab scale process is needed. In the previous part, an alternative on lab scale was

found namely the CTSU. This part presents the comparison between the results of the CTSU and two

pilot scale processes: the Pilot of FTE (PilotFTE) on the one hand and the Pilot of Vandemoortele

(PilotVDM) on the other hand. Four blends were used in this evaluation: two reference samples

(Shst20 and Pst20) and two cake margarine based samples (margarine fat and margarine).

4.3.1 General overview of the three crystallizers and the experimental set-up

Figure 4.12 presents the set-up of each crystallizer. PilotVDM consists of a mixing tank and a high

pressure pump that forwards the emulsion to the first SSHE (CS1), after which different cooling steps

and treatments are possible. Sequence of the different steps can be changed. At the end of the

process, the product can go to a resting tube for further crystallization. During the experiments the

sequence of the steps was kept constant (see Figure 4.12): four scraped surface heat exchangers

(SSHE) ensured different cooling steps (CS), followed by a pin worker for post treatment (PT) of the

crystallized sample. For the margarine samples a resting tube (RT) was included after the pin worker as

further hardening was necessary for packaging. For one test with Pst20 an intermediate treatment (IT)

was added after the second cooling step. For each run on this pilot crystallizer around 70kg of the

sample was used. For each fat blend and margarine different cooling regimes were applied in the

SSHE’s. Depending on these temperatures the fat will crystallize faster or slower at respectively lower

or higher cooling temperatures, resulting in end products with different properties

The pilot of FTE (PilotFTE) is smaller and consists out of one cooling step and a post-treatment (see

Figure 4.12). The amount of sample needed for this pilot was around 25kg.

The CTSU, on lab scale consists of one cooling cell and no further treatment. Around 1kg of sample was

necessary for this set-up.


PilotVDM PilotFTE CTSU

Figure 4.12: Scheme of the different steps in the PilotVDM, PilotFTE and CTSU

After every step in both pilots, samples were collected in tubs and the product temperature was

measured. These tubs were subsequently stored at 20°C for two weeks. The storage stability of these

samples was monitored by measuring the SFC and hardness after one day, one week and two weeks.

To be able to compare the results of the PilotVDM and the PilotFTE, the samples were grouped based

on their temperature immediately after the process. For each fat blend different temperatures were

selected from the different steps in the PilotVDM and the PilotFTE. Additionally, these fat blends were

crystallized in the CTSU at these temperatures. For example, for the production of a margarine: the

temperature measured immediately after filling was 15,6°C for CS2, and 15,4°C for CS4. These samples

were than compared with a product made at 15°C in the CTSU. The different temperatures chosen for

the different steps in both pilots are shown in Table 4.5.The temperatures of the different parts of the

pilots and the different tests are shown in appendix 1.

Table 4.5: The different temperatures used on the CTSU to compare with the products on both pilot scales

PilotVDM PilotFTE

Sample CS1 CS2 IT CS3 CS4 PT RT CS PT

Shea stearin blend (Shst20) 10°C 10°C / 15°C 15°C 15°C / 10°C 20°C

Palm stearin blend (Pst20) 15°C 10°C / 6°C 10°C 15°C / 10°C 15°C

Margarine fat (MargFat) 15°C 10°C / 7°C 10°C 15°C / 7°C 20°C

Margarine (Marg) 25°C 15°C / 15°C 15°C / 20°C 15°C 15°C

Mixing

Cooling step 1 (CS1): SSHE


Intermediate treatment (IT): pinworker



Post-treatment (PT): pinworker

Resting tube

Mixing

Cooling step (CS): SSHE

Post-treatment (PT): pinworker

Cooling step (CS): SSHE


In addition to the monitoring of the SFC and hardness during storage, the microstructure was also

studied by polarized light microscopy (PLM) and, for the margarine samples the water droplet size

distribution was determined. To compare the cake margarines on a consumer level, cakes were

produced with the margarines of the PilotVDM and the CTSU. Structure as well as hardness of the

cakes was examined.

To be able to compare the results from these two pilots with the CTSU, the shear forces of the

different processes were taken into account as different shear forces lead to different product

properties. To have an indication of these shear forces, the tip speed was calculated for each process,

as seen in Equation 2. Both pilots have a higher tip speed then the CTSU. A higher tip speed is

indicative for higher shear forces.

Equation 2: General formula of the tip speed(a), calculation of the tip speed of the pilots(b) and of the CTSU(c)

(

) ( )

( )

( )

(

)

( )

(

)

( )

4.3.2 Microstructural characterization of the fat blends

The microstructure of the different samples made on the CTSU, PilotVDM and PilotFTE was compared

using PLM.

In Figure 4.13(a) the first (CS1) and last step (PT) of the PilotVDM were compared for the sample

Shst20. The left part of the image shows the microstructure of the post-treatment that is characterized

by a regular crystal network with finer crystals than after the first cooling step. The sample after the PT

experienced more shear forces as it went through the five steps of the pilot process and therefore

crystals were finer.

The comparison between a shear time of 30 minutes and 2h for Shst20 at 20°C in the CTSU is shown in

Figure 4.13(b). Both samples showed a uniform network of fine crystals that only differs in the amount

of air bubbles that are present. These air bubbles are indicated by the arrows. They show a

characteristic black edge around the air bubbles. After thirty minutes of shearing some air bubbles

were observed but after 2h of shearing the amount of bubbles significantly increased making it difficult

to distinguish the crystal structure. So it can be concluded that more air was trapped with increased

shear time. This is possible because the CTSU has a large headspace filled with air. Trapping of the air


in the sample was possibly also influenced by the shape of the stirrer or by turbulence during stirring.

These air bubbles were not observed on pilot scale.

PILOT PT – CS1 CTSU 2h – 30’

(a) (b)

Figure 4.13: Comparison of the microstructure (PLM) of samples made with the CTSU, PilotFTE and PilotVDM. (a) Shst20 PilotVDM PT (left) – CS1 (right), (b) Shst20 CTSU 2h (left) – 30’ (right). The arrows indicate some air bubbles.

Figure 4.14 illustrates the differences in microstructure of margarine made in the CTSU and the two

pilots. The left side of the images always presents the sample of the CTSU. The comparison was made

between margarine made at 25°C and sheared for 1h30, and margarine after CS1 of the PilotVDM in

Figure 4.14(a). Figure 4.14(b) visualizes the comparison between margarine made at 15°C for a shear

time of 2h and margarine after PT of the PilotFTE. The samples were prepared by taking a small

amount of the two different margarines, putting them next to each other on a slide, adding a cover slip

and applying an equal pressure on both margarines with another slide. It can be seen that the right

side of the images were darker than the left side, as the thickness of the margarine layer originating for

the pilot was considerably higher. This was due to the higher hardness and plasticity of the pilot-

margarines and so it was not possible to obtain a thin layer making the comparison with the CTSU

more difficult. However, it was clear from the images that the margarines of the CTSU and the

margarines of the two pilots had fine crystals with an uniform distribution.


MARGARINE: CTSU – PILOT VDM MARGARINE: CTSU – PILOT FTE

(a) (b)

Figure 4.14: Comparison of the microstructure (PLM) of samples made with the CTSU, PilotFTE and PilotVDM. (a) Marg25 CTSU (left) – PilotVDM CS1 (right), (b) Marg15 CTSU (left) – PilotFTE PT (right). The arrows indicate some air bubbles.

Figure 4.15 shows the comparison between a fat blend made with the CTSU and a fat blend made with

respectively the PilotVDM (Margarine fat) and the PilotFTE (Pst20). The samples were prepared similar

to the margarine samples. For both images (a and b), the air bubbles between the fat crystals are

clearly visible for the samples prepared in the CTSU as indicated with arrows. Margarine fat crystallized

at 10°C for a shear time of 2h and Margarine fat after CS2 of the PilotVDM was compared in Figure

4.15(a). The microstructure was more regular for the sample made by the CTSU, but the crystals were

bigger. The high shear forces applied on the sample of the PilotVDM created more small crystals.

Figure 4.15(b) visualizes the comparison between Pst20 made at 10°C and sheared for 30min and Pst20

after CS of the PilotFTE. It can be seen that the sample produced on the CTSU contained two different

entities, namely a regular network of fine crystals in which darker grains (encircled in Figure 4.15(b))

are embedded. Although the sample looked as a smooth sample, but microstructural, grains were

present. As these grains were mostly harder than the matrix, it was not possible to get a thin layer. The

layer of the grains will thus be thicker and darker because it was more difficult for the light to pass

through. Both the samples of the CTSU and the PilotFTE had fine crystals. There was a uniform

distribution of the crystal network in the sample of the PilotFTE and no grains were observed.


FAT BLEND: CTSU – PILOT VDM FAT BLEND: CTSU – PILOT FTE

(a) (b) Figure 4.15: Comparison of the microstructure (PLM) of samples made with the CTSU, PilotFTE and PilotVDM. (a) MargFat10 CTSU (left) – PilotVDM CS2 (right), (b) Pst10 CTSU (left)– PilotFTE CS (right). The arrows indicate some air bubbles and the circles indicate some grains.

4.3.3 Evaluation of the fat blends and margarine samples as function of

storage time

This part presents the comparison of quality parameters between the samples made at both pilots and

the CTSU as function of storage at 20°C. After 1 day, 1 week and 2 weeks, both the SFC and hardness

were measured and the results were compared

4.3.3.1 CTSU versus PilotFTE for the different fat blends

This part presents the results of the comparison between the CTSU and the PilotFTE. For the three fat

blends, Pst20, Shst20 and MargFat, the trends were almost similar so the results of Pst20 are discussed

as a representative example. Figure 4.16 shows the comparison between the CTSU and the PilotFTE for

the palm stearin blend (Pst20). Only the two extreme values of the shear times (30’ and 2h) in the

CTSU are shown, the values of the intermediate shear followed the results of these extreme values.

The results of the other fat blends are shown in appendix 2.

Observations for SFC

Palm stearin blend

In the cooling step (Figure 4.16(a)), the SFC of the palm stearin blend didn’t show significant

differences between the different set-ups. For both the CTSU at 10°C and the CS, the SFC remained

constant during storage which was due to the high crystallization rate of palm stearin (see 3.3). The

SFC of the PT in the palm stearin blend (Figure 4.16(b)) remained constant during two weeks of storage

due to high crystallization rate of palm stearin and the high shear forces. The SFC of the CTSU samples


produced at 15°C increased during storage for one week. Only the samples with short shear times

continued to increase till the SFC was significantly higher than the SFC of the PilotFTE. The SFC of the

samples produced at longer shear times remained constant during the second week and was similar to

the SFC of the PT.

Margarine fat

The SFC showed the same trends in the CTSU and the PilotFTE for both steps. The SFC of the PilotFTE

remained constant during two weeks of storage. The SFC of the CTSU samples increased the first week

and remained constant in the second week. The crystallization of the margarine fat samples was not

yet completed after the process although the blend contained also palm stearin, but the amount of

palm stearin was much lower than in the blend with palm stearin (20% instead of 50%). The SFC was

similar for both set-ups at the CT but was significantly higher for the CTSU samples at the second step.

Shea stearin blend

During the first step, the SFC of the blend with shea stearin increased during the two weeks for both

the PilotFTE and the samples of the CTSU but the SFC of the PilotFTE was significantly higher than the

SFC of the CTSU. The crystallization was not yet completed after two weeks of storage due to the slow

crystallization rate of shea stearin (see 3.3). During the second step, the SFC increased for the PilotFTE

but decreased for the CTSU samples

Observation for hardness

Palm stearin blend

From Figure 4.16(a) of the first step in the process, it can be seen that the hardness of the PilotFTE is

much higher than the hardness of the samples produced in the CTSU, although the difference in SFC

was small. The lower hardness was probably due to the high amount of air bubbles in the samples of

the CTSU (see 4.3.2 Microscopy). It was not possible to measure the hardness of the CTSU samples

after one day, the hardness was too low due to the air bubbles in the samples.

After one day, the hardness of the CTSU samples was also very small in the second step of the process

of PilotVDM as seen in Figure 4.16(b). Both the hardness of the CTSU and the PT of the PilotFTE of the

palm stearin samples increased significantly during the first week of storage. After two weeks the

hardness of the PilotFTE significantly decreased but the hardness of the CTSU samples slightly

increased and the hardness became similar to the samples at low shear times in the CTSU. The

decrease in hardness after two weeks of the PilotFTE samples can be caused by the formation of grains

or by Ostwald ripening. Ostwald ripening is the growth of larger crystals at the expense of smaller


crystals and is related to the solubility gradient found between small and large crystals (Rousseau,

2000; Oijo et al, 2004).

For every blend it was concluded that with an increased shear time, the hardness decreased as at

higher shear times, more air bubbles were trapped in the sample. The difference in hardness between

the samples of the CTSU and the PT of the PilotFTE were also smaller than at the CS. As the

crystallization temperature of the samples in Figure 4.16(b) was higher than in Figure 4.16(a), the

crystallization goes slower and less crystals were formed during the process and thus more sintering

occurs in the samples of the CTSU during storage (see Table 4.5 and Figure 4.16).

Margarine fat

The hardness in the cooling step showed the same trend as the palm stearin blend. The hardness of

the blends with margarine fat remained constant in the PilotFTE but the hardness of the CTSU samples

increased during the first week of storage and remained than constant. The hardness of the CTSU

samples was significantly higher than the sample of the PT from one week of storage.

Shea stearin blend

For both steps of the process, the same trends in hardness can be seen as for the margarine fat. Only

the hardness remained significantly lower during the storage.

10°C 15°C

(a) (b)

Figure 4.16: Hardness (N) and SFC (%) in function of the storage time for the comparison of (a) CTSU Pst10 – PilotFTE CS and (b) CTSU Pst15 – PilotFTE PT


4.3.3.2 CTSU versus PilotVDM for the different fat blends

The trends for hardness and SFC of the CTSU versus PilotVDM were similar as the ones between CTSU

and PilotFTE. In the values of the intermediate shear followed the results of these extreme values. , the

results of the palm stearin blend were compared with the CTSU and the PilotVDM. The results of the

other two fat blends are shown in appendix 3. Only the two extreme values of the shear times (30’ and

2h) in the CTSU are shown, the values of the intermediate shear followed the results of these extreme

values.


Palm stearin blend

For both the palm stearin blend and the margarine fat, the SFC showed different trends when the

crystallization temperatures of the CTSU samples was lower than 15°C (see Table 4.6) than samples

produced at temperatures of 15°C or higher. For the palm stearin blend, it can be seen that the SFC

remained constant during the storage for the samples produced at temperatures lower than 15°C. The

crystallization was already completed during the process. At crystallization temperatures of 15°C or

higher, the SFC of the samples of the PilotVDM remained constant during storage. The SFC of the CTSU

on the other hand still increased after 1 week storage. The same was observed for the samples with a

shorter shear time, crystallization continued until the second week. This increase was due to an

incomplete crystallization during the shearing process as it was crystallized at a higher temperature.

The SFC of the PilotVDM was similar or slightly higher than that of the CTSU for all crystallization

temperatures.

Margarine fat

For the margarine fat at all crystallization temperatures, there was a small increase of the SFC for the

samples made in the CTSU. At crystallization temperatures lower than 15°C, the SFC of the PilotVDM

was higher than the samples of the CTSU, but reached the same point after two weeks of storage. At

temperatures higher than 15°C, the SFC of the PilotVDM was lower for the whole storage time but the

difference between the SFC of the two set-ups became smaller at the end of storage.

Shea stearin

The SFC of the shea stearin blend increased during storage and the crystallization rate of the samples

of the CTSU and PilotVDM was similar. The SFC of both CTSU and PilotVDM was similar after two weeks

of storage.

For all the three blends, the final SFC after two weeks of storage was between 30 and 35%, as

established for the blending of the samples (see 3.1.1 Material and Methods).


Observations for hardness

In Table 4.6 the results are shown of the comparison between the CTSU and the PilotVDM for the palm

stearin blend. Also the hardness was influenced by the crystallization temperature. At temperatures

lower than 15°C, the hardness of the samples made at the CTSU was around 1N and much lower than

the hardness of the samples of the PilotVDM after two weeks of storage (CS2: 13,9N, CS3: 9,1N and

CS4: 9,8N). When there were crystallized at temperatures higher or equal to 15°C, the hardness was

around 5N and the difference with the hardness of the samples of the PilotVDM (CS1: 12,9N, PT: 9,7N)

was smaller. At the CTSU, the samples with a short shear time showed a higher hardness than the

samples of long shear times. This can again be explained by the amount of air bubbles in the sample as

this increased when the shear time was longer (see 4.3.2 Microscopy). It can also be seen that for

every blend, both for the CTSU and the PilotVDM samples the hardness remained almost constant or

showed a limited increase during storage.

Table 4.6: The comparison between the CTSU and the PilotVDM for the blend with palm stearin

Hardness (N) SFC (%)

1 day 1week 2weeks 1day 1week 2weeks

15

°C

CTSU 30’ 0,2±0,0(a,A) 5,8±0,3(a,B) 7,0±0,4(a,C) 25,2±1,4(a,A) 30,7±1,7(a,B) 35,0±0,7(a,C)

CTSU 2h 0,1±0,0(a,A) 3,5±0,3(b,B) 2,4±0,6(b,C) 27,1±1,6(a,b,A) 30,4±1,3(a,B) 28,1±1,7(b,A,B)

PILOT CS1 10,8±2,2(b,A) 12,9±0,6(c,A) 12,9±1,6(c,A) 28,7±1,0(b,A) 30,2±0,8(a,A) 29,8±0,4(b,A)

10

°C

CTSU 30’ *(a,A) 1,5±0,1(a,B) 1,2±0,1(a,B) 30,1±0,2(a,A) 29,2±0,6(a,B) 29,4±0,4(a,B)

CTSU 2h *(a,A) 0,7±0,0(a,B) 0,8±0,1(a,B) 30,1±0,3(a,A) 30,4±1,1(a,A) 30,0±1,3(a,A)

PILOT CS2 13,7±1,2(b,A) 12,3±1,9(b,A) 13,9±0,9(b,A) 33,2±0,8(b,A) 33,4±0,3(b,A) 33,6±0,4(b,A)

6°C

CTSU 30’ 0,2±0,0(a,B) 4,5±0,3(a,B) 0,4±0,1(a,B) 28,5±0,5(a,A) 29,2±1,0(a,A) 29,1±0,3(a,A)

CTSU 2h 0,3±0,0(a,A) 0,6±0,1(b,B) 1,1±0,1(b,C) 26,7±0,1(a,A) 29,3±1,3(a,B) 30,7±0,6(a,B)

PILOT CS3 10,5±1,7(b,A) 11,6±2,1(c,A) 9,1±0,6(c,A) 35,4±0,6(b,A) 35,6±0,6(b,A) 33,6±0,1(b,B)

10

°C

CTSU 30’ *(a,A) 1,5±0,1(a,B) 1,2±0,1(a,B) 30,1±0,2(a,A) 29,2±0,6(a,B) 29,4±0,4(a,B)

CTSU 2h *(a,A) 0,7±0,0(a,B) 0,8±0,1(a,B) 30,1±0,3(a,A) 30,4±1,1(a,b,A) 30,0±1,3(a,b,A)

PILOT CS4 8,5±1,9(b,A) 9,4±0,9(b,A) 9,8±0,2(b,A) 32,6±0,6(b,A) 32,5±0,0(b,A) 32,6±0,1(b,A)

15

°C

CTSU 30’ 0,2±0,0(a,A) 5,8±0,3(a,B) 7,0±0,4(a,C) 25,2±1,4(a,A) 30,7±1,7(a,B) 35,0±0,7(a,C)

CTSU 2h 0,1±0,0(a,A) 3,5±0,3(b,B) 2,4±0,6(b,C) 27,1±1,6(a,A) 30,4±1,3(a, B) 28,1±1,7(b,B)

PILOT PT 9,8±1,2(b,A) 9,0±1,0(c,A) 9,7±1,0(c,A) 31,8±0,8(b,A) 33,6±0,9(a, B) 32,3±0,0(c,A,B)

*hardness was not detectable In a column, the results with the same lower-case letter (a,b,c) are not significantly different (p < 0,05) In a row, the results with the same capital letter (A,B,C) are not significantly different (p < 0,05)


4.3.3.3 The evaluation of the different steps in the pilot processes during storage

This part presents the evaluation of the different steps in the PilotFTE and PilotVDM for a selected fat

blend. At a particular step in the pilot process, both the hardness and SFC will be influenced by the

process parameters but also by the parameters of the previous steps. This effect was not present for

the samples of the CTSU because this is a batch process.

Figure 4.17 presents the two steps of the PilotFTE together with the corresponding sample of the CTSU

for the palm stearin blend. The SFC was not significant different and it remained constant during the

process, the hardness however increased. More network formation and more sintering occurred

during the last step. The temperature at the last step was also higher than the first step. As mentioned

before, the sintering during storage was more distinct at higher crystallization temperatures.

Figure 4.17: The evaluation of the different steps in the PilotFTE for the palm stearin blend after 1 week

Figure 4.18 visualizes the process of the PilotVDM with the corresponding samples of CTSU for

margarine fat. After the second cooling step, the SFC increased to remain stable afterwards. The SFC of

the CTSU stayed constant during the whole process but was lower than the SFC of CS2, CS3 and CS4 of

PilotVDM. The hardness of the four cooling steps of the PilotVDM was similar but at the last step, the

PT, the hardness decreased. The PT kneaded the product and the fat crystal network was partially

broken down resulting in a lower hardness. The hardness of the CTSU did not follow the same trend:

after CS1 and PT the hardness was higher than at the other steps due to the higher crystallization

temperature leading to more sintering during storage.


Figure 4.18: The evaluation of the different steps in the PilotVDM for margarine fat after 1 week

The hardness of the CTSU did not show the same trend as the hardness of the PilotVDM for the

different steps. The production of a sample of the CTSU had only one step and was not influenced by

another step. The SFC was similar between the two methods; there was no big influence of the

previous steps on the SFC of the samples of the pilot processes.

From these results it can be concluded that there are still a lot of differences between the fat blends

produced on the CTSU and on both pilots. Although some similarities were found in SFC, the hardness

was much smaller at the CTSU samples than in both pilots. These differences are due to the capturing

of air in the samples reducing the hardness.

4.3.3.4 CTSU versus PilotFTE for margarine

The comparison between the PilotFTE and the CTSU for margarine is shown in Figure 4.19. The

differences between the hardness of the CTSU and the PilotFTE became smaller when the storage time

increased but they were still significant. There was no significant difference between the SFC of the

PilotFTE and the CTSU, they remained both constant.


15°C

Figure 4.19: Hardness (N) and SFC (%) in function of the storage time for the comparison of CTSU Marg15 – PilotFTE CS, PT

4.3.3.5 CTSU versus PilotVDM for margarine

In the last step a cake margarine was produced by the CTSU. The comparison was made between the

CTSU and both the PilotFTE and PilotVDM.


The first cooling step of the pilot was performed at 25°c and simulated in the CTSU (Figure 4.20(a)) The

SFC of the CTSU samples did not change the first week but increased in the second week. Figure 4.20(a)

shows the comparison between the CS1 of the PilotVDM and the CTSU samples made at 25°C. Both

set-ups showed the same trend, there was a large increase in SFC during the first week and in the

second week, the SFC remained constant. After two weeks, the SFC of the CS1 was significantly lower

than the SFC of the CTSU samples. The higher the crystallization temperature, the bigger the increase

in SFC will be, because of the formation of less crystals during the process. The CS2, CS3 and CS4 of the

PilotVDM for margarine are compared with the samples of the CTSU crystallized at 15°C, as shown in

Figure 4.20(b). The SFC of CS2 is lower than the other samples but increased during the first week to

reach a similar value as the samples of the CTSU and the PilotVDM (CS3 and CS4). Both the SFC of the

samples of the CTSU and CS3 and C4 remained constant during the storage at a similar SFC. After 2

weeks of storage, the samples of the CTSU and the PilotVDM reached the same level. In Finally, the SFC

of the RT was compared with the SFC of margarine crystallized in the CTSU at 20°C. The SFC was similar


for the PilotVDM and CTSU samples after 1 day and 2 weeks and overall, the SFC increased during the

storage for both set-ups but with a different progress. This can be seen in Figure 4.20(c). The SFC of the

RT increased in the first week and remained constant in the second week.

15°C 20°C

(a) (b)

25°C

(c)

Figure 4.20: Hardness (N) and SFC (%) in function of the storage time for the comparison of (a) CTSU Marg15 – PilotVDM CS2, CS3, CS4, (b) CTSU Marg20 – PilotVDM RT, (c) CTSU Marg25 - PilotVDM CS1


Observations for hardness

Both the hardness of the samples of the CTSU crystallized at 25°C and the CS1 increased during the

storage time, as seen in Figure 4.20(a). There were no similarities between the two set-ups but the

differences were again small, especially at the shorter shear times. The CS2, CS3 and CS4 of the

PilotVDM were compared with samples of the CTSU in Figure 4.20(b). The hardness of the samples in

the PilotVDM was higher than the hardness of the CTSU samples during the first week but after two

weeks, the hardness of the samples of the CTSU at low shear times had a similar hardness of the

samples of CS3 and CS4, the hardness of CS2 remained the highest. During the storage time, the

hardness of the PilotVDM remained constant, but the samples of the CTSU increased, due to sintering,

so the differences in hardness between the PilotVDM and the CTSU became smaller during storage.

The hardness was again higher for low shear times due to less capturing of air at short shear times than

for long shear times. In Figure 4.20(c) can be seen that both the hardness of the CTSU samples at 20°C

and the sample of the RT increased during storage. After one week of storage, the hardness of the

samples with low shear times in the CTSU were similar to the sample of the RT, the hardness of the

other CTSU samples was significantly lower than the samples of the RT. However the differences in

hardness were not as large as in the fat blends. At the samples crystallized at 20°C and 25°C, both the

hardness and the SFC increased during the storage. The crystallization was not completed during the

shearing process due to the high crystallization temperatures.

4.3.3.6 The evaluation of the different steps in the pilot processes during storage of

margarine

The SFC was similar for the two process steps (CS and PT) and also for the samples of the CTSU and the

PilotFTE. However Figure 4.21(a) shows that there was a big difference in hardness between the two

set-ups; the hardness of the CTSU was much lower than the hardness of the PilotFTE. For the samples

of the PilotFTE, the hardness was smaller for the PT. There was some breakdown of the crystal network

due to the working of the PT.

The different steps of the PilotVDM and the samples of the CTSU were compared. The results are

shown in Figure 4.21. The SFC was equal for both set-ups in the first two steps. Thereafter, the SFC of

samples produced on the pilot the PilotVDM increased at CS3 and remained unchanged for the

following steps. The SFC of the CTSU remained constant during the four cooling steps but decreased

during resting (RT). This decrease was probably due to the higher crystallization temperature in the PT.

The hardness of the different steps in the PilotVDM remained constant; there was no breakdown of

the network in the last step as at the PilotFTE. The hardness of the samples of the CTSU was

significantly lower than the hardness of the samples of the PilotVDM.


(a) (b)

Figure 4.21: The evaluation of the different steps in (a) PilotFTE and in (b) PilotVDM for margarine after 1 week

The results of the margarine samples made at the CTSU had more similarities with the results of the

pilots than the fat blends. The SFC of the CTSU showed a lot of similarities but the hardness was still

small in comparison with the pilot samples. The results of the microscopy showed also air bubbles in

the margarine made with the CTSU. When the crystallization temperatures were above 15°C, the

hardness of the samples produced in the CTSU at short shear times was similar to the margarine

produced on the pilots.

4.3.4 Water droplet size distribution

The water droplet size distribution of margarine is an important quality parameter. Therefore the

water droplet size distribution of the two pilot set-ups and the CTSU were compared. The samples that

are crystallized at 15°C or 20°C with a shear time of 30min or 1h in the CTSU were chosen due to their

similarities with the PilotVDM and PilotFTE. For the PilotVDM and PilotFTE the samples of respectively

the CT and PT, and the CS4 and RT are compared with the CTSU. The results of the D3,3 or average

diameter, the standard deviation and the 97,5% value of the samples are shown in Table 4.7. The

water droplet size distribution of the samples of the PilotVDM was too small to measure as in a cake

margarine the diameter is around 0,2µm (van Duynhoven et al, 2002). Margarine can be considered as

a microbiological safe product as the water droplet size distribution is smaller than a micro-organism

(0,5 – 5µm). The small water droplets were the result of the high shear forces on the emulsion, the

emulsifier will stabilize the small droplets in the fat phase. At the PilotFTE, the geometrical weighted

mean diameter was around 3,5µm, 10 times larger than at the PilotVDM, which was due to the lower

shear forces. Additionally only 2 steps were present in this pilot resulting in bigger water droplets. The


droplet size was for 97,5% of the water droplets around 8,9µm and 11,6µm for respectively the first

and second step of the PilotFTE. This means that micro-organism can grow and multiply in the product.

The samples made with the CTSU had a water droplet size distribution that was more than 100 times

bigger than the droplet size at the PilotVDM, they had also a very large distribution, some droplets

were even bigger than 1mm. The large size and broad distribution is due to the rather low shear forces

in the CTSU. The water droplet size and the distribution of the samples crystallized at 15°C were

smaller at longer shear times. When the crystallization was done at 20°C there was no difference

between 30min and 1h of shear. The droplet size distribution of the samples crystallized at different

temperatures is similar.

Table 4.7: The D3,3, standard deviation and 97,5% values (µm) of different margarine samples

D3,3 (µm) stdev (µm) 97,5% (µm)

CTSU 15°C 30min 77,8 5,0 1840,0

CTSU 15°C 1h 31,4 3,6 392,0

CTSU 20°C 30min 59,4 5,5 1670,0

CTSU 20°C 1h 63,0 5,1 1559,0

PilotFTE CS 3,5 1,6 8,9

PilotFTE PT 3,4 1,9 11,6

PilotVDM test 1 CS4 * * *

PilotVDM test 1 RT * * *

*not measurable

4.3.5 Cake tests

In this part, sponge cakes were prepared with the different cake margarines to assess the effect of the

crystallization procedure on the final cake structure. Six cakes were prepared: two with the final

margarines from trail 1 (PilotVDM_Marg1) and 2 (PilotVDM_Marg2) and four with margarines from the

CTSU. These four margarines were selected based on their similarities with the margarines made on

the PilotVDM (see 4.3.3.4 and 4.3.3.5): two crystallized at 15°C with 30 minutes (CTSU15°C_30’) and

one hour (CTSU15°C_1h) of shearing, and two crystallized at 20°C with 30 minutes (CTSU20°C_30’) and

one hour (CTSU20°C_1h) of shearing. The six cakes were visually evaluated by comparing the crumb

structure and the hardness was measured by texture analysis.

The photographs of a slice taken from the six cakes are shown in Figure 4.22. These photos give an idea

of the difference in texture and the loaf size. It can be that for cakes prepared with the margarines


from the PilotVDM (Figure 4.22(a) and (d)) the air bubbles were bigger and less homogenously

distributed in the cakes, resulting in a coarser texture. No visual differences were observed between

the cakes prepared with margarine of the CTSU. These cakes were characterized by a finer texture with

small air bubbles. Some bigger air bubbles are still present but in much lesser extent than in the cakes

made of the margarine of the pilot.

(a) (b) (c)

(d) (e) (f)

Figure 4.22: Photographs of the loaf size of sponge cake with (a) PilotMarg1, (b) CTSU15°C_30’, (c)CTSU15°C_1h, (d)PilotMarg2, (e)CTSU20°C_30’ and (f)CTSU20°C_1h

In general, the quality characteristic of the cakes didn’t show many differences. Their volume and

crumb were similar; although the density of the dough was smaller for the margarines made with the

CTSU (see Figure 4.23(a)). This can be explained by the air bubbles that were captured in the margarine

of the CTSU (see before) giving a lower density to the dough.

In addition to the visual comparison, the hardness of the loaf size was measured with a penetration

test of which the results are shown in Figure 4.23(a). The hardness of the cakes of PilotVDM_Marg1

was significantly different from that of the cakes with margarines of the CTSU, while the hardness of

the cakes with PilotVDM_Marg2 were only different with the cakes made by margarine of the CTSU

crystallized at 15°C. The hardness of the cake with Marg15_1h was significantly lower than the cakes


made with Marg20_30’ and Marg20_1h. This trend was also seen for the hardness of the margarines.

The margarines crystallized at 15°C had a lower hardness than these crystallized at 20°C. Furthermore,

the hardness of the cakes was plotted against the density of the cake (see Figure 4.23(b)) and a linear

correlation (R² = 0,97) could be found. This means that a lower density of the cake will give a lower

hardness of the cake. Both parameters were influenced by the capture of air in the margarine made

with the CTSU. There will be more air bubbles in the dough because there was already air in the

margarine. This will cause, after the baking, a more aerated cake characterized by a lower hardness.

(a) (b)

In the bars: the results with the same lower-case letter (a,b,c) are not significantly different (p < 0,05)

Figure 4.23: (a) Hardness of the cakes made with different margarines and (b) the linear correlation between hardness and the dough density

a,b c

b,d b,c,d cC

a

Conclusions | 60

5 Conclusions

Since the last years, the health issue about saturated and trans unsaturated fatty acids has encouraged

the food industry to make new margarines with less saturated and trans fatty acids. These new

margarines have to be tested before the industrial production can start. This is done on pilot scale but

these tests still need a lot of (fat) ingredients and time.

In this study a method was developed to produce margarine products on lab scale as an alternative to

pilot scale. In the first part a fundamental study was executed on crystallization under shear by

measuring the SFC and rheological parameters. It was clear that shear enhanced the crystallization and

this resulted in a faster increase of the SFC and a higher final SFC. Especially the slow crystallizing shea

stearin blend (at 15°C) showed a much steeper SFC profile when shear was applied. Next to monitoring

the SFC, also oscillatory rheology was used to study the effect of shear. After cooling the sample, a

shear step with different shear rates and with different shear times was applied. This step was

followed by an isothermal period at static conditions. Both the shear rate and time had a large

influence on the apparent viscosity in the shear step. All fat blends showed an earlier increase in

apparent viscosity at higher shear rates due to a faster crystallization. However, the higher the shear

rate, the smaller the increase in apparent viscosity, resulting in a lower equilibrium value for the

samples at higher shear rates. It could be seen that the apparent viscosity was similar for the shear

rates of 300s-1 and 500s-1. At these shear rates no aggregation is possible because the contact time

between the colliding entities was too short to aggregate. The crystallization proceeded in two steps

but this was less visible for the samples crystallized at 20°C, they tended to go to one step. At the end

of the shear step, the final apparent viscosity was the highest for the lowest shear rates as there was

less structural breakdown. The |G*| of the shea stearin blend in the period without shear went fast to

an equilibrium for all shear rates. At the end of the isothermal period, the curves reached a similar

value. For the palm stearin blend, the crystallization proceeds different at the period without shear.

The increase is much slower and there is a clear difference between the two lowest (75s-1 and 150s-1)

and the two highest shear rates (300s-1 and 500s-1).

In the second part of the research a method was developed and optimized on lab scale as alternative

for the pilot scale. The first technique, the RVA was not suitable as it was not possible to adapt the

procedure due to the limitations of the device. Also a post treatment with the TNO cell lead to the

development of grains (β crystals) in the shea stearin blends during the storage. A second technique,

that was tested, was a controlled temperature shearing unit (CTSU) developed for the production of fat

blends and margarine on lab scale. The procedure of the CTSU was optimized by using higher shear

rates and longer shear times. The results with the shea stearin blend showed no grains during storage

Conclusions | 61

of two weeks. As the CTSU technique seemed suitable for crystallization under shear on a small scale,

the next step was to compare its performance with the PilotVDM and PilotFTE.

Next to the palm stearin and shea stearin blend, also a cake margarine fat and cake margarine were

compared between the pilots and the CTSU. From the images of the PLM, it was seen that air was

captured in the samples of the CTSU. This phenomenon had a large influence on the hardness of the

samples, especially for the fat blends. The hardness of the CTSU samples was much smaller compared

to the blends processed in both pilots. The biggest differences were observed for the samples

crystallized at temperatures below 15°C. The SFC was also significantly lower in the CTSU but the

differences between the CTSU and the pilots were not that big. For the margarine samples, there were

still some differences in hardness but much smaller than for the fat blends. The SFC during the whole

process was similar between the different pilots and the CTSU. The most similarities, in both hardness

and SFC, were seen at lower shear times (30min). The water droplet size distribution of the margarine

samples for the different set ups were examined. The smallest water droplet size distribution was

found for the samples made by the PilotVDM, followed by the samples of the Pilot FTE and the biggest

water droplet size distribution was for the CTSU samples. Higher shear forces will result in a smaller

water droplet size distribution. At the end, the margarines were compared on consumer level by

preparing cakes with the margarines of the CTSU and the PilotVDM. The hardness of the cakes was

similar or slightly lower for the cakes with the margarine of the CTSU. The loaf size of the different

cakes was visually evaluated. The loaf size of the cakes made with margarine of the PilotVDM showed

larger air bubbles and a more heterogeneous structure. However the loaf size of the cakes with

margarine of the CTSU showed a homogeneous structure with small air bubbles. There were no

differences seen between the cakes of the margarines made at different temperatures and shear times

at the CTSU.

The CTSU was thus not suitable to crystallize fat blends that are similar with the pilot scale. However

the margarine products on the CTSU showed a lot of similarities with the margarine on the pilots and

even on consumer level, almost no differences were observed. So the CTSU seemed to be a valuable

tool to produce margarine on lab scale as alternative for pilot scale.

Further research | 62

6 Further research

In this research it is concluded that there were many similarities between the margarine products in

the CTSU and the pilots, but this was not the case for the comparison with the fat blends. Optimization

is needed to improve the crystallization of both the fat blends and the margarine on lab scale. As seen

in the research, the biggest problem was the capturing of air in the samples. This can be avoided by

reducing the headspace in the CTSU or by using another stirrer type to trap less air in the sample.

Another possibility to improve the method is to use a continuous process with several steps, instead of

a batch system. During this process, different temperature profiles are imposed on one sample. The

TNO cell as post treatment did not give the desired properties, but other post treatments can be tested

which are similar to a pin worker as used on pilot scale.

In this study, only a cake margarine was tested. In further research, it can be tested whether this setup

is suitable for other sorts of margarine.

References| 63

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Appendix| 66

Appendix

Appendix 1 Processparameters of the PilotVDM and the PilotFTE

Temperatures of the samples taken at the different steps in the process for the PilotVDM

Temp. (°C) CS1 CS2 CS3 CS4 PT/RT

Shea stearin blend 11,7 9,3 16,1 12,9 15,6

Palm stearin blend 17,7 10,0 5,4 10,0 13,0

Margarine fat 15,6 10,6 6,6 11,8 15,5

Margarine 24,2 15,6 13,7 15,4 18,6

Temperatures of the samples taken at the different steps in the process for the PilotFTE

Temp. (°C) CS PT

Shea stearin blend 9,8 22,5

Palm stearin blend 10,8 18,9

Margarine fat 7,7 21,1

Margarine 11,6 16,2

Appendix| 67

Appendix 2 CTSU versus PilotFTE of the shea stearin blends and the margarine fat

The results of the comparison between the CTSU and the PilotFTE for the shea stearin blend.

The comparison is showed between Shst20 crystallized at 10°C and the CS of the PilotFTE (a) and

between Shst20 crystallized at 20°C and the PT of the PilotFTE.

(a) (b) The results of the comparison between the CTSU and the PilotFTE for the palm stearin blend

The comparison is showed between MargFat crystallized at 7°C and the CS of the PilotFTE (a) and

between MargFat crystallized at 20°C and the PT of the PilotFTE.

(a) (b)

Appendix| 68

Appendix 3 CTSU versus PilotVDM of the shea stearin blends and the margarine fat

The results of the comparison between the CTSU and the PilotVDM for the shea stearin

blend.

Hardness (N) SFC (%) 1 day 1week 2weeks 1day 1week 2weeks

10

°C

CTSU 30’ 3,3±0,4(a,A) 5,8±0,3(a,B) 1,6±0,1(a,C) 31,8±0,3(a,A) 35,9±1,0(a,B) 35,9±1,0 (a,B)

CTSU 2h 0,8±0,1(b,A) 0,9±0,1(b,A) 2,1±0,1(a,B) 31,1±0,3(a,b,A) 34,1±2,3(a,B) 35,1±2,3(a,B)

PILOT CS1 12,9±0,5(c,A) 11,1±1,5(c,A) 17,5±1,4(b,B) 27,7±0,8(b,A) 31,6±0,2(b,B) 31,6±0,2(b,B)

10

°C

CTSU 30’ 3,3±0,4(a,A) 5,8±0,3(a,B) 1,6±0,1(a,C) 31,8±0,3(a,A) 35,9±1,0(a,B) 35,9±1,0 (a,B)

CTSU 2h 0,8±0,1(b,A) 0,9±0,1(b,A) 2,1±0,1(a,B) 31,1±0,3(a,b,A) 34,1±2,3(a,b,B) 35,1±2,3(a,A,B)

PILOT CS2 10,7±1,8(c,A) 12,9±1,1(c,A) 10,8±0,5(b,A) 29,6±1,3(a,A) 32,8±0,3(b,B) 32,8±0,3(b,B)

15

°C

CTSU 30’ 4,6±0,3(a,A) 5,2±0,3(a,A) 2,1±0,0(a,B) 33,4±1,1(a,A) 33,4±0,8(a,A) 32,2±1,7 (a,A)

CTSU 2h 1,7±0,1(b,A) 1,7±0,2(b,A) 3,2±0,4(a,B) 34,9±1,9(a,A) 32,6±0,8(a,b,B) 37,2±1,6(a,A)

PILOT CS3 12,0±1,1(c,A) 11,8±2,1(c,A) 11,4±1,6(b,A) 31,6±1,8(b,A) 32,8±0,8(a,A) 35,1±1,8(a,B)

15

°C


CTSU 2h 1,7±0,1(b,A) 1,7±0,2(b,A) 3,2±0,4(a,B) 34,9±1,9(a,A) 32,6±0,8(a,b,B) 37,2±1,6(b,A)

PILOT CS4 9,0±0,2(c,A) 9,6±0,5(c,A) 9,5±0,2(b,A) 30,2±0,9(b,A) 30,1±1,3(b,A) 31,4±0,3(a,A)

15

°C


CTSU 2h 1,7±0,1(b,A) 1,7±0,2(b,A) 3,2±0,4(a,B) 34,9±1,9(a,A) 32,6±0,8(a,b,B) 37,2±1,6(b,A)

PILOT PT 6,6±0,6(c,A) 12,4±0,8(c,B) 7,0±1,0(b,A) 28,3±1,5(b,A) 30,0±1,5(a,A,B) 31,9±0,4 (a,B)

In a column, the results with the same lower-case letter (a,b,c) are not significantly different (p < 0,05) In a row, the results with the same capital letter (A,B,C) are not significantly different (p < 0,05)

Appendix| 69

The results of the comparison between the CTSU and the PilotVDM for margarine fat.

Hardness (N) SFC (%) 1 day 1week 2weeks 1day 1week 2weeks

15

°C

CTSU 30’ 3,5±0,1(a,A) 3,5±0,1(a,A) 6,4±0,5(a,B) 34,4±0,1(a,A) 36,0±0,9(a,B) 36,4±1,5(a,B)

CTSU 2h 1,6±0,0(a,A) 3,2±0,2(b,B) 2,0±0,1(b,A) 35,0±0,3(a,b,A) 35,2±1,2(a,A) 37,9±1,3(a,B)

PILOT CS1 10,6±1,5(b,A) 12,9±2,6(c,A,B) 14,7±0,1(c,B) 30,1±0,5(b,A) 33,7±0,6(a,B) 32,4±0,3(b,C)

10

°C

CTSU 30’ 2,3±0,0(a,A) 0,5±0,0(a,B) 0,2±0,0(a,B) 31,8±0,3(a,A) 34,5±1,0(a,B) 35,7±1,4(a,B)

CTSU 2h 0,2±0,0(b,A) 0,4±0,0(a,B) 0,7±0,1(a,C) 32,0±2,1(a,A) 34,1±1,7(a,A) 34,7±0,6(a,A)

PILOT CS2 10,5±3,4(c,A) 14,5±0,8(b,A) 14,0±0,3(b,A) 37,2±0,3(b,A) 38,4±0,9(b,A) 34,5±0,3(a,B)

7°C

CTSU 30’ 0,2±0,(a,A) 0,5±0,0(a,B) 0,7±0,0(a,B) 30,9±1,5(a,A) 34,5±1,6(a,B) 34,4±1,5(a,A)

CTSU 2h 0,3±0,0(a,A) 0,7±0,0(a,B) 0,8±0,0(a,C) 30,8±2,0(a,A) 35,4±0,8(a,B) 34,4±1,0(a,B)

PILOT CS3 12,0±0,6(b,A) 15,2±0,5(b,B) 12,1±0,1(b,A) 37,1±0,6(b,A) 38,0±0,6(b,A) 34,7±0,3(a,B)

10

°C

CTSU 30’ 2,3±0,0(a,A) 0,5±0,0(a,B) 0,2±0,0(a,B) 31,8±0,3(a,A) 34,5±1,0(a,B) 35,7±1,4(a,B)

CTSU 2h 0,2±0,0(b,A) 0,4±0,0(a,B) 0,7±0,1(a,C) 32,0±2,1(a,A) 34,1±1,7(a,A) 34,7±0,6(a,A)

PILOT CS4 9,5±0,4(c,A) 14,4±0,1(b,B) 11,4±0,7(b,C) 35,4±0,4(b,A) 38,4±0,4(b,B) 34,6±0,3(a,A)

15

°C

CTSU 30’ 3,5±0,1(a,A) 3,5±0,1(a,A) 6,4±0,5(a,B) 34,4±0,1(a,A) 36,0±0,9(a,B) 36,4±1,5(a,B)

CTSU 2h 1,6±0,0(a,A) 3,2±0,2(b,B) 2,0±0,1(b,A) 35,0±0,3(a,b,A) 35,2±1,2(a,A) 37,9±1,3(a,B)

PILOT PT 5,6±0,4(a,A) 9,9±0,6(c,B) 8,8±0,7(a,B) 28,6±1,0(b,A) 36,5±1,3(a, B) 34,4±0,2(b,C)

In a column, the results with the same lower-case letter (a,b,c) are not significantly different (p < 0,05) In a row, the results with the same capital letter (A,B,C) are not significantly different (p < 0,05)

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