Answering the Challenge:

Label-friendly Emulsifiers and

Surfactants for Food Systems

Prof. Pete Wilde

2nd annual Clean Label Conference

March 31-April 1, 2015, Westin Hotel, Itasca, Ill.

Making Emulsions

(and foams)

Oil droplets

How to make a solid

from 2 liquids

Oil droplets

Dilute emulsion

Droplets free to move,

behaves like a liquid.

Viscosity c(1 + 2.5 Vd)

(Einstein, 1906)

Concentrated emulsion

Vd 0.6, droplets trapped

Liquid motion arrested

behaves as a “solid”

Small droplets m “rigid” spheres

Role of Emulsifiers

Aid breakup of droplets by reducing interfacial tension

Droplet shape during emulsification

High interfacial tension

Applies to both emulsions and foams

Low interfacial tension Stabilise droplets against coalescence

Unstable

Stable

Interfacial tension

Force acting around

the droplet to

minimise surface free

energy, and keep

droplet spherical

F F

Properties of emulsifiers

Hydrophobic

Hydrophilic

HLB = Hydrophilic:Lipophilic Balance

HydrophobicLow HLB

(oil soluble)

HydrophilicHigh HLB

(water soluble)

Size, structure, charge

Oil

Oil

Water

Preferred Interfacial curvature

High HLBFoams,

Oil – in – water emulsions

Low HLBWater in oil emulsions

HLB Use

4-6 W/O emulsifiers

7-9 Wetting agents

8-18 O/W emulsifiers

13-15 Detergents

10-18 Solubilizers

Interfacial StabilityThe importance of curvature

Hydrophobic

Hydrophilic

HLB = Hydrophilic:Lipophilic Balance

HydrophobicLow HLB

HydrophilicHigh HLB

o/w

w/o

High HLB Low HLB

Stable Unstable

StableUnstable

Size, structure, charge

Food Emulsifiers & Surfactants

Ancient Greeks used beeswax in cosmetic products

Egg yolk traditionally used as an emulsifier - rich in phospholipids

Replaced by phospholipids (lecithin) extracted from soy in 1920’s

More effective, synthetic emulsifiers developed based on fatty acid derivatives

Mono- and di-glycerides of fatty acids

Lecithins

Naturally occurring molecules, but mass produced by chemical

modification. Refined / enriched to control HLB and functionality

Tend to be extracted from plant sources or egg. Can be further

refined/enriched to give better control over HLB, and functionality.

(Poly)sorbates and sucrose estersSynthetic emulsifiers with highly controlled range of HLB and

functionalities .

Esters of monoglycerides (Lactylate, citrate, polyglycerol)

Chemically modified esters of monoglycerides with specific

functionalities.

Emulsifiers Uses & Functions

Mayonnaise, sauces, soups – Emulsify and stabilise fat by

adsorbing and reducing interfacial tension and providing stable

interfacial layer

Margarines & Spreads – Emulsify and stabilise water phase.

Prevent splattering, stabilise and control fat crystal network

structure.

Chocolate – Emulsify and stabilise different phases, stabilise

fat and sugar. Improve consistency during filling and moulding,

reduce bloom formation.

Fat

Sugar

Protein

Cocoa

Emulsifiers Uses & Functions

Bread & Baked products – Emulsify and stabilise

shortenings, stabilise gas cells. Control starch – gluten

interactions. Controls dough strength, loaf volume, crumb

structure and shelf life.

Meat products – Emulsify and stabilise water and

fat phases, particularly in reduced fat products.

Improves texture and taste.

Ice cream and whipping cream– Emulsify and

stabilise fat droplets. Destabilise interfaces to

promote partial coalescence to develop

structure formation. Stabilise ice crystals to

maintain texture.

Air bubble

Thin aqueous film

Gluten/StarchMatrixFat

Clean label solutions

• Direct Replacements – “Natural” alternatives

• Additional or Alternative Functionalities

• Modifications & Processing Aids

“Natural” Emulsifiers

Quillaja extract - from inner

bark of the soapbark (Quillaja

saponaria, Molina). Rich in

saponin – natural surfactant

Bile salts – derived from

cholesterol, secreted by gall

bladder, excellent emulsifiers,

aid digestion of fats. Used a

supplement in bile deficiency.

Potential Food Emulsifier ?

“Natural” Emulsifiers

Lipoproteins, Nature’s own emulsions. Energy store

Egg yolk, soy, sunflower etc…

Oil bodies in plants and animal tissues.

Highly stable, energy efficient.

Phosholipids, surface active proteins (oleosins, apo-

lipoproteins, hydrophobins etc)

Assembled on an individual basis, slow manufacture.

Tend to be locked into structures, eg fat globule

membranes – poor solubility

Hence, purification / refinement required

no longer clean label?

Oil body

Iipoprotein

Chloroplast

“Natural” Emulsifiers

Chloroplasts, thylakoid membranes packed with

galactolipids.

Bound up in structure, but free galactolipids linked with

improved functionality in breadmaking (see enzyme

section).

Galactolipids may also modulate fat digestion and may

help reduce appetite.

Need targeted processing to help develop as a “natural”

ingredient.

MonoGalactosylDiacylGlycerol

(MGDG)

MonoGalactosylMonoacylGlycerol

(MGMG)

“Natural” Emulsifiers

Hydrophobins – secreted by filamentous

fungi to help hyphae break through water

surface

Froghopper – cuckoospit froth.

Natural, but not tasty

Excellent long term

stability of bubbles in

ice cream, and

responsible for

“gushing” in beer.

But……

Food or Additive?

Grape seed and apple tannins: Emulsifying and antioxidant

properties.

Figueroa-Espinoza, Maria Cruz; Zafimahova, Andrea;

Alvarado, Pedro G Maldonado; et al.

Food chemistry Volume: 178 (2015) Pages: 38-44

Emulsions stabilised by

grape and apple tannins

Optimization of extraction conditions and fatty acid

characterization of Lactobacillus pentosus cell-bound

biosurfactant/bioemulsifier

Vecino, Xanel; Barbosa-Pereira, Letricia; Devesa-Rey,

Rosa; et al.

Journal of the Science of Food and Agriculture Volume:

95 (2015) Issue: 2 Pages: 313-320

Using biosurfactants produced

by lactic acid bacteria. Efficient

as surfactants, but clean label?

Production of exopolysaccharides by Lactobacillus

helveticus MB2-1 and its functional characteristics in

vitro

Li, Wei; Ji, Juan; Rui, Xin; et al.

LWT- Food Science and Technology Volume: 59

(2014) Issue: 2 Pages: 732-739

Exopolysaccharides

produced by lactic acid

bacteria with emulsifying

properties. Interesting

properties but clean label?

Emerging Research

Proteins and Polymeric Emulsifiers

Hydrophobic

groups at core of

molecule

Oil / Air Phase

Aqueous Phase

InteractionsUnfolding to expose

hydrophobic groups to

surface

Proteins vs Surfactants

Strong interactions High mobilityWeak interactions

Restricted mobility

Protein Mixed Surfactants

Foam & Emulsion Stability

Short range

Thin film

Polymers and Emulsion Stability

Proteins and polymers can confer excellent long term stability

Some proteins, eg hydrophobins create strong,

elastic interfaces which prolong stability and

can improve texture and mouthfeel.Protein

1

2

3

4

5

6

7

0 10 20 30 40 50

Fat Content (vol %)

Per

ceiv

ed F

at C

on

ten

t (S

core

)

Sensory perception

Surfactant

Natural carbohydrate – protein complexes (eg

gum arabic, sugar beet pectins) form thick,

bulky structures at surface, conferring excellent

long term steric stabilisation.

Protein

Carbohydrate

However, high molecular

weight, not efficient

during emulsification, so

high concentrations /

high energy required

Pickering Stabilisation

Emulsions stabilised by particles with

defined surface hydrophobicity.

Some small starch granules (quinoa,

rice) can form stable emulsions.

Fat crystals can also be used, but

sensitive to heat treatment.

Large size warrants high energy required

to form emulsions initially.

Surface modification

improves functionality

Modification & Processing Aids

There are many natural, clean label emulsifiers, but often not in a functional form

Adams et al.

Extraction, isolation and characterisation of oil bodies

from pumpkin seeds for therapeutic use.

Food Chemistry 2012 Volume 134, Issue 4, Pages

1919–1925

Oil bodies are already in an emulsified form

Could their natural

emulsifying properties be

exploited by in situ use of

oil bodies

Modification & Processing Aids

Lipases in breadmaking

Gas cell in bread are stabilised primarily be

polar lipids.

Lipid composition of bread affects loaf volume

and quality

Addition of emulsifiers such as DATEM and

SSL improve baking quality.

Flour polar lipids

C16:0 - FA

C14:0 - FA

C18:2 - FA

Flour non-polar lipids

Flour total lipids

Loaf

volu

me (

ml)

Gas cell development

Gluten starch matrix Gas cells

Lamellae

Coalescence “Sponge” transition

• CO2 production – bubble expansion during proofing and

oven spring

• Bubbles in contact rely on interfacial stability

• Early coalescence – loss of loaf volume

Mixing Proofing Baking

Type of Lipids

Polar Lipids TAG FFA DAG

%m

ol T

ota

l L

ipid

s

0

10

20

30

40

50

60

70

Flour Dough Liquor Foam

Dough liquor foam and lipid composition

Fatty acids concentrate in foam

TAG do not accumulate in foam, but some present

which may cause instability

Using lipase to alter lipid profile

Gerits LR. et al. Food Chemistry 156 (2014) 190–196

40424446485052545658

Control YieldMAX Lipolase Lecitase Lipopan

Loaf

Vo

lum

e (

ml)

Lipase

FFA

DGDG DGMG

MGDG MGMG

PC LPC

Conversion of polar lipids

from di-Acyl to Mono-Acyl

Strong correlation with

loaf volume

Summary

Emulsifiers and surfactants have been developed and optimised for

functional performance – adsorption, emulsification, stabilisation,

texture modification etc.

Natural, clean label alternatives becoming will probably never match

bespoke emulsifiers for performance.

Understanding the structure – function – performance relationships of

conventional ingredients is key to developing viable replacements.

Emerging research is revealing new sources of active ingredients, but

not all will be clean label.

Process modification and addition functionalities of some clean label

solutions do make them viable alternatives.

……Thank you

Louise Salt, Fiona Husband, Mike Ridout

Irene Gonzalez-Thuillier, Byoung Min

Peter Shewry, Richard Haslam, Paola Tosi

Simon Penson, Gemma Chope

Acknowledgements

2nd annual Clean Label Conference

March 31-April 1, 2015, Westin Hotel, Itasca, Ill.