CHARACTERIZATION OF GELATINS FROM DIFFERENT PART OF

SOME FISHES

SYAMSURIEYA BINTI MOHAMED

Final Years Project Submitted in

Partial Fulfilment of the Requirements for the

Degree of Bachelor of Science (Hons.) Food Science and Technology

In the Faculty of Applied Sciences

Universiti Teknologi MARA

JANUARY 2012

This Final Year Project Report entitled “Characterization of Gelatin from Different Part of Some Fishes” was submitted by Syamsurieya binti Mohamed, in partial fulfillment of the requirements for Degree of Bachelor of Science (Hons.) Food Science and Technology, in the Faculty of Applied Sciences, and was approved by

Assoc. Prof. Dr. Cheow Chong Seng Supervisor

B.Sc. (Hons.) Food Science and Technology Faculty of Applied Sciences Universiti Teknologi MARA

40450 Shah Alam Selangor

Dr. Anida Yusoff Assoc. Prof. Dr. Noorlaila Ahmad Project Coordinator Programme Coordinator B.Sc. (Hons) Food Science and Technology B.Sc. (Hons.) Food Science and Technology Faculty of Applied Sciences Faculty of Applied Sciences Universiti Teknologi MARA Universiti Teknologi MARA 40450 Shah Alam 40450 Shah Alam Selangor Selangor

Date:

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ACKNOWLEDGEMENTS

All the praise to God, for His mercy has given me idea, patience, and strength to complete

this Final Year Project. My work was accomplished under guidance, sympathetic attitude,

inexhaustible inspiration and enlightened supervision of Associate Professor Dr. Cheow

Chong Seng. I wish to offer my heartiest gratitude to my caring and kind supervisor for

his untiring help, suggestions, step-by-step guidance and close supervision during the

conduct of the investigation and in preparation of this report.

I would also like to express my gratitude to Pn. Norahiza and all my friends for their help

and inspiring cooperatives. I would like to thank them for being good friends to me.

Finally, I will like to give my sincere thanks to my adorable son and lovely husband for

their moral support and valuable assistance in my academic pursuits. I also would like to

take this opportunity to extend my thanks to my beloved parents, their prayer and help.

Both moral and financial support, have help me much during my studies.

May God bless all these people with long, happy and peaceful lives.

Syamsurieya binti Mohamed

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TABLE OF CONTENTS

Page

ACKNOWLEDGEMENT iii

TABLE OF CONTENT iv

LIST OF TABLES vi

LIST OF FIGURES vii

LIST OF ABBREVIATIONS viii

ABSTRACT ix

ABSTRAK x

CHAPTER 1 INTODUCTION

1.1 Background and problem statement

1.2 Significance of study

1.3 Objectives of study

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2

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CHAPTER 2 LITERATURE REVIEW

2.1 Collagen and gelatin

2.2 The quality of gelatin

2.3 The application of gelatin

2.4 Fish gelatin

2.5 Differential Scanning Calorimetry, Rheometer, and Chromameter

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Page

CHAPTER 3 MATERIALS AND METHODS

3.1 Material

3.2 Analysis of gelatin

3.2.1 Determination of melting point

3.2.2 Viscosity measurement

3.2.3 Colour measurement

3.2.4 Statistical analysis

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CHAPTER 4 RESULTS AND DISCUSSION

4.1 Melting point of gelatin by Differential Scanning Calorimetry (DSC)

4.2 Viscosity measurement of gelatin

4.3 Colour of gelatin

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CHAPTER 5 CONCLUSION AND RECOMMENDATION 26

CITED REFERENCES 28

APPENDIX 33

CURRICULUM VITAE 37

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LIST OF TABLES

Table Caption Page

3.1 Type of gelatins 13

4.1 The melting point of gelatins 17

4.2 The colour values for solution of gelatins 23

4.3 The colour values for gel of gelatins 24

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LIST OF FIGURES

Figure Caption Page

4.1 The melting point of commercial gelatin (GA) 19

4.2 The melting point of fish gelatin from skin of Labeo rohita (GD)  20

4.3 The melting point of fish gelatin from air bladder of Cirrhinus mrigala (GG) 

20

4.4 The melting point of fish gelatin from bone of Cirrhinus mrigala (GH) 

21

4.5 The viscosity of fish gelatins 23

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LIST OF ABREVIATION

BSE : Bovine Spongiform Encephalopathy

g : gram

GA : commercial gelatin

GB : fish gelatin from skin of Catla catla

GC : fish gelatin from skin of Cirrhinus mrigala

GD : fish gelatin from skin of Labeo rohita

GE : fish gelatin from skin of Cyprinus carpio

GF : fish gelatin from air bladder of Catla catla

GG : fish gelatin from air bladder of Cirrhinus mrigala

GH : fish gelatin from bone of Cirrhinus mrigala

GI : fish gelatin from bone of Catla catla

GJ : fish gelatin from bone of Labeo rohita

h : hour

mg : miligram

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ABSTRACT

CHARACTERISATION OF GELATINS FROM DIFFERENT PART OF SOME

FISHES

Fish gelatin was chosen as the alternative for the bovine and porcine gelatins. Fish gelatin

can be made up from fish by product. In fish industries, about 70% parts of fish were

removed and it will increase the waste of fish by product. In contrast, with the production

of fish gelatin, it will reduce the waste of fish by product as well as producing a clean and

halal gelatin to consumer of all religion and cultures. In this study, fish gelatins were taken

from skin, air bladder and bone of Catla catla, Cirrhinus mrigala, Labeo rohita and

Cyprinus carpio. The samples are in solid form. Meanwhile the reference is commercial

gelatin (bovine gelatin) in powder form. The gelatins were characterised for melting point,

viscosity and colour. Thermal properties of gelatins were studied using Differential

Scanning Calorimetry (DSC). The melting point of commercial gelatin was the highest

and followed by fish gelatin from air bladder of Cirrhinus mrigala and Catla catla, as well

as fish gelatin from skin of Cirrhinus mrigala and Cyprinus carpio. The viscosity of

gelatins was measured using rheometer. The effect of temperature on viscosity showed

that the viscosity of gelatin solution decreased as the temperature increased. It was due to

the changes of polypeptide chain and the hydrogen bonding between chains. The fish

gelatin extracted had slightly yellowish in colour compared to commercial gelatin, which

was more whitish in the solution and gel form. The findings in this study revealed that fish

gelatin have the opportunity to be commercialised if the thermal and rheology properties

were improved to be match to the commercial gelatins.

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ABSTRAK

PENCIRIAN GELATIN DARIPADA PERLBAGAI BAHAGIAN IKAN YANG

BERLAINAN

Gelatin ikan digunakan sebagai ganti kepada sumber gelatin yang berasakan lembu dan

khinzir. Di dalam industri perikanan, dianggarkan 70% daripada bahan-bahan lebihan ikan

yang dibuang telah menyebabkan peningkatan bahan-bahan buangan. Sebaliknya, dengan

penggunaan semula bahan-bahan ini akan membantu mengurangkan jumlah bahan yang

dibuang. Secara tidak langsung dapat membantu golongan yang tidak menggunakan

produk yang berasaskan lembu dan khinzir. Gelatin ikan juga adalah di kategorikan

sebagai halal dan bersih. Dalam kajian ini, gelatin ikan diambil daripada kulit, pundi udara

dan tulang ikan dari pelbagai jenis seperti ikan Catla catla, Cirrhinus mrigala, Labeo

rohita dan Cyprinus carpio. Sampel gelatin ikan adalah dalam keadaan kepingan pepejal

dan sampel untuk rujukan adalah dalam bentuk serbuk. Pencirian gelatin telah ditentukan

dengan menentukan takat lebur, kelikatan, dan juga warna. Takat lebur dan penggunaan

haba atau tenaga oleh gelatin telah ditentukan dengan menggunakan Differential Scanning

Calorimetry (DSC). Takat lebur bagi komersial gelatin adalah yang paling tinggi

berbanding yang lain, diikuti oleh takat lebur dari gelatin ikan yang berasal dari pundi

udara ikan Cirrhinus mrigala dan Catla catla. Begitu juga dengan takat lebur gelatin dari

kulit ikan Cirrhinus mrigala dan Cyprinus carpio. Manakala, kesan daripada perubahan

suhu pada kelikatan menunjukkan yang semakin tinggi suhu, semakin rendah kelikatan

gelatin. Ia adalah kerana perubahan pada rantaian polipeptida dan juga rantaian ikatan

hidrogen. Penemuan dari pada kajian ini menunjukkan gelatin ikan boleh dikomersialkan

dengan menambahbaik ciri gelatin ikan ini supaya menyamai gelatin yang telah

dikomersialkan.

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CHAPTER 1

INTRODUCTION

1.1 Background and problem statement

Gelatin was patented in England in 1754 and today it was classified as food stuff

with E-number and is usually used in food because of unique, natural and

multifunctional. This multifunctional properties and rarely allergic to human,

has made it to be used not for food but also in pharmaceutical and photographic

industries (PB, 2011).

Gelatin is normally derived from land animal such as cow or pig where the skin,

bone and connectives tissue contain a fibrous insoluble protein collagen

(Norizah, 2005). This gelatin is produces after introducing to alkali or acid

treatment and a water soaking step before it is dried and form a gelatin in

powder form to be distributed to the manufactures.

Nowadays, demand for the alternative source of gelatin has been increasing for a

number of reasons such as mad cow and foot and mouth diseases as well as

demand for the religious and cultured practised requirement. Besides Islam,

Judaism and Hindu are also facing the problems about the origin of the gelatin.

Judaism is forbidding the consumption of any pork-related product. Meanwhile

Hindu will do not consume cow-related product. In addition, Islam also forbid to

consume pork-related product but cow is accepted unless the cow is slaughtered

not according to Islamic Law. It will be considered as unclean or non halal.

Therefore, the research on gelatin from fish by-product has increased as an

alternative source to replace the porcine and bovine gelatin. Besides, the use of

fish by product will reduce the fish waste which is reported to be almost 70% in

the fish industries. Fish is marine animal and it is considered not toxic and

poisonous, Islam and other religion is allowed to eat without doubt.

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However, in the production of fish gelatin, the quality characteristic of gelatin

must be studied. The usual characteristics as compare to the commercial gelatin

(bovine and pork gelatin) are the gel strength, gelling and melting point,

viscoelasticity and also the protein content.

From previous research, researchers claimed that the main problem facing by

fish gelatin are low gelling and melting point and low elastic and viscous

modulus for gel (Leunbeger, 1991). The fish gelatin can be obtained from

different parts of fish. All these differences and weakness need to be overcome.

1.2 Significance of study

The production of fish gelatin is a new culture. Since many researchers realised

that many consumers were concerned about the origin of the gelatin. The fish

gelatin will become a very popular gelatin product since it will be accepted by

all religion and cultures. This study was determine the melting point of fish

gelatin and compared to commercial gelatin (bovine gelatin). In the production

of food, it is important to control the temperature especially in the production of

food containing gelatin. The temperature of gelling and melting of gelatin is

controlling in order to determine the flow and time during food production. It is

also important in order to determine the type and condition of food storage. The

characteristic of gelatin is important to ensure that this type of gelatin is suitable

and fit to be used as a food ingredient in food industries and also to overcome

the problems regarding to the melting point of fish gelatin. The viscosity of

gelatin is important to determine the flow of gelatin. It is important especially in

manufacturing because the viscosity of gelatin used must be standardized. This

investigation was also carried out to determine colour of fish gelatin as colour is

an important property that attract the consumer especially the manufacturers.

Furthermore, if the use of fish gelatin can be commercialised over the world and

it can be replaced porcine and bovine gelatin and also it will help to reduce the

quantity of waste of the fish by-product.

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1.3 Objectives of study

The aims of this research were to determine some of the characteristic of fish

gelatins and compare to the commercial gelatins (bovine gelatin). Specifically

the objectives are:

I. To determine the melting point of gelatin from different part of fishes

using DSC

II. To determine the viscosity of fish gelatin solution using rheometer

III. To determine the colour values of gelatin solution and gel using

chromameter.

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CHAPTER 2

LITERATURE REVIEW

2.1 Collagen and gelatin

Gelatin is a food additive used in edible product such as ice cream, jelly and

baked product. The function as a gelling agent, stabilising agent, emulsifying,

dispersing and thickening agent make this gelatin really useful in the industry

(Ward and Court, 1977). For example in the food industry, gelatin is use as

stabilising agent in the production of ice cream (Brody, 1965). Gelatin not only

use in food industry but also in pharmaceutical industry, cosmetic and

photography (Karim and Bhat, 2009).

Gelatin is derived from animal tissue called collagen. Collagen played an

important role to support the body structure of animal. The collagen is mostly

found in skin, tendon, cartilage, bone and connective tissue (Ward and Court,

1977). The collagen from by-product of land animal will be subjected to

treatment process such as alkali and acid treatment. After all the process, the

structure of collagen will break down and the product produce is known as

gelatin. The processes involve in the production of gelatin for commercial

manufacturing of gelatin are extraction, filtration and clarification, evaporation,

sterilisation, drying, grinding and sifting, and storage (Ward and Court, 1977).

However, the gelatin produce have different behaviour due to acid and alkali

process. It showed that the process or treatment is playing an important role in

choice of gelatin. In addition, by manipulating pre-treatment and process

condition, the quality of gelatin can be controlled to the desired standard

(Gudmunsson and Hafsteinsson, 1997). Furthermore the source and type of

collagen also influence the properties of the gelatin (Binsi et al., 2009).

Collagen molecules compose of three α-chains intertwined and known as

collagen triple helix where the interchain is form by hydrogen bonding. When

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applying heat above 40ºC, it will destabilise the triple helix by means of a helix

to coil transition and leading to conversion into soluble gelatin (Gomez-Guillen

et al., 2005).

2.2 The quality of gelatin

Collagen is a group of protein and according to Dakin, (1920) gelatin that

produced from the collagen is an incomplete protein because it lacks of

tryptophan but higher in lysine and methionine which are some of the essential

amino acid. The amino acids found in gelatin are alanine, glycine, valine,

leucine, isoleucine, proline, phenylalanine, tyrosine, serine, threonine, cystine,

methionine, arginine, histidine, lysine, aspartic acid, glutamic acid,

hydroxyproline, and hydroxylysine (Dakin, 1920).

Besides the amino acids, gelatin also contains moisture, ash, calcium, copper

and iron (Ward and Court, 1977). According to Ward and Court, (1977) the

moisture content of gelatin is different at different pH. They claimed that

moisture content is increasing if the pH is increasing.

However composition such as ash, calcium, copper, and iron must be in lower

amount in gelatin. It is because these composition will give low quality of

gelatin. For example, if more than 2 ppm of iron content in gelatin, it will result

in grey strain on food product (Ward and Court, 1977). In addition, colour of

gelatin also depends on the raw material extracted (Ockerman and Hansen,

1999). The official standard of good quality of gelatin is require it to be free of

objectionable taste or offensive odour and colour.

The other quality factor in gelatin is the calories. The gelatin with low in

calories is recommended in food product. Gelatin is also utilised to reduce

carbohydrate levels in foods formulated for diabetic patient (Karim and Bhat,

2009). Nowadays, the quality of gelatin is not the only issues. For the people

who had strong believed in the religion, they always aware of the issue of

allowed and not allowed to eat foods (Choi and Regenstein, 2000).

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Therefore, some of the big companies produced gelatin from the animal which is

no doubtful in religion. One of the animals is fish. However, the characteristic of

the fish gelatin must be almost same or much better than the gelatin of land

animal. Some researchers were doing on this matter in order to control and

improve the fish gelatin. The researchers were doing experiment on different

type of fish and using different part of fish to produce fish gelatin. Choi and

Regenstein (2000) claimed that fish gelatin has very similar properties to pork

gelatin and in addition, fish gelatin release of aroma and flavor.

In fish gelatin, the amino acid composition is the same as the bovine gelatin. The

differences are on the amount of each amino acid. According to Cheow et al.,

(2007), glycine and imino acid (pro + Hyp) were the most abundant amino acids

in bovine gelatin, compare to fish gelatin. It is back to the original structure of

collagen. Limited imino acid content should result in a less statically hindered

helix and may affect the dynamic properties of gelatin (Johnson-Bank, 1990).

Meanwhile, Eastoe (1965) was supported that fish collagens has a similar amino

acid distribution to mammalian collagen, however, the imino acid is decreased

and serine and threonine were increased.

Gelatin usually used as an ingredient to improve elasticity, consistency and

stability of foods. For example, gelatin is used as thickening of sauces and

gelling of pate (Cheow et al., 2007). Gelatin also provides a melts in mouth

function and to achieve a thermo-reversible gel property (Herpandy, 2011).

There are too many usefulness of gelatin in industries. According to Karim and

Bhat (2009), gelatin is one of the most accepted biopolymers and is extensively

utilized in food because of its unique functional and technologies properties.

Gelatin has a distinguishing property of dissolving in hot water and congealing

of it were called melting point and setting point respectively. Gelatins extracted

from different raw materials have different setting temperature, melting point

and gel strength due to different amino acids content and peptide structure (Liu

et al., 2008). As gelatin binds with water, it swells and absorbs water. It is

because in aqueous gelatin, the hydrogen bond will bind with water in present of

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many exposed polar region. As the concentration of gelatin increase, the rate of

gelation also increases. Thereby, increasing the firmness and decreasing

tenderness. In most food system, the acceptable gelatin concentration is between

1.5 and 4% (McWilliam, 2001).

2.3 The application of gelatin

In order to be applied to food industries, fish gelatin must possess the following

characteristic. Gelatin from fish by product must have rheological properties

such as gel strength, gelling and melting point (Cho et al., 2005). However

many factors will affected the quality of gelatin, they are average molecular,

concentration of gelatin solution, gel maturation time, gel maturation

temperature, pH and salt content (Karim and Bhat, 2009). According to Ali

(2010), gelatin usually contains 90% protein, 18 types of amino acids and 7

essential for people to consume. The high quality of gelatin are contains high

protein, low ash and heavy metal, small molecular weight, easy absorption and

utilisation, high biological value, promoting absorption of vitamin and mineral.

Besides, the raw material of fish by-product must be available in a large quantity

and its economical collection is essential to be continuously produced in

industry (Cho et al., 2005).

Gelatin is used as a jellying agent. In sugar jellies production, gelatin will give

the gel and delay crystallisation of the sugar in the jellies. Previously, the gelatin

is added with Arabic gum in the production of tougher jellies. But it still needs

to reduce the moisture content by stored in the stove. Fortunately, by using

higher concentration of gelatin, the goods no need for stove (Ward and Court,

1977). Gelatin will reduce the moisture content in sugar jellies. Gelatin is a

water-loving material and can absorb up to ten times its weight in water

(GMAP, 2011).

Gelatin, commonly low in calories, it is recommended for use in the foodstuff to

boost protein level and partially useful in body-building foods (Karim and Bhat,

2009). Gelatin also use as whipping agent. In the production of gelatin

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marshmallow, the viscosity is increased by high over-runs. It will due to

problem of high viscosity. In order to reduce it, a very high bloom strength

gelatin is used when making extruded marshmallow (Ward and Court, 1977).

Other function of gelatin is as a stabiliser. In ice cream, stabiliser is used to

prevent the formation of coarse ice crystals and gelatin was the easiest stabilizer

used. It also decreases the rate of melting, give body and a firm smooth texture

(Ward and Court, 1977).

A study on fish gelatin added to food product also was done by Cheng et al.,

(2008), they found that a decreasing in fish gelatin to pectin ratio resulted in an

increase in bulk density, firmness, compressibility, adhesiveness, elasticity and

melt ability of low fat spread. Gelatin also use as an emulsifier in mayonnaise,

thickening agent in canned soups and adhesive in sugar confectionary product

(Ward and Court, 1977).

It showed that the demand for gelatin is high and in these recent issues of the

halal and kosher food, will increasing the demand of high quality of gelatin. It

was supported by Karim and Bhat (2009) the global demand for gelatin has been

increasing over the year. Choi and Regenstein (2000) also estimated that world

usage of gelatin is 200 000 metric tons per year with U.S usage being about 30

000 metric tons per year only for food products. The annual world output of

gelatin increased to 326 000 ton with the highest source being pig-skin (46%),

bovine hide (29.4%), bones (23.1%), other source (1.5%). It showed that the

source of halal gelatin do not meet the demand in the market (Herpandi et al.,

2011).

2.4 Fish gelatin

There are two types of gelatin can be produced. Type A gelatin with isoelectric

point at pH 6 – 7 is produced from acid treatment and type B with isoelectric

point at pH 5 is produced from alkali treatment (Karim and Bhat, 2009).

However, according to Liu et al., 2008, the pretreatment of fish skin must be

mild due to the high content of soluble collagen which makes it easily

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hydrolysed by acid or alkali. In addition, gelatin from frozen and fresh fish also

gives the different results. Fernandez-Diaz et al. (2003) reported that gelatin

from frozen skins had lower gel strength values as compared to fresh skin. Many

researchers reported that the gelling and melting point of fish gelatins are lower

than those of land animals, and the gel strength is also lower than that of land

animals (Gomez-Guillen et al., 2002). Even the melting point of fish gelatin is

low, it will resulting in faster dissociation in the mouth with no residual ‘chewy’

mouth feel (Arnesen and Gildberg, 2006).

Gelatin from marine source (warm and cold-water fish skins, bones and fins) is a

possible alternative to bovine and pork gelatin (Kim and Mendis, 2006).

According to Brody (1965) there are a few countries that lack of land animal but

plenty of marine sources. Therefore, fish gelatin can be used as the alternative

source better than no gelatin at all. Furthermore, fish gelatin does not associated

with the risk of outbreaks of Bovine spongiform Encephalopathy (BSE) and foot

and mouth disease (FMD) (Badii and Howell, 2006; Jangjareonrak et al., 2005).

Gelatin produced from bovine and porcine cannot be added for foods due to

tradition and religious objections (Sadowska et al., 2003). According to Karim

and Bhat (2009) both Judaism and Islam forbid the consumption of any pork-

related products, while The Hindu do not consume cow-related product, as well

as the stricter and enhanced adhere vegetarianism. Products from fish with

removable scale are accepted in Judaism with minimal restrictions, while all fish

are acceptable in Islam since it does not poisonous. In addition, the consumption

of bovine-related products is accepted unless the bovine has been slaughtered

according to Islamic Law (Nadiah, 2010). Huda et al. (1999) also added that as

long as the fish does not contain toxins and poison it will consider as Halal.

Besides, it also is a good waste management as well as economically beneficial

(Haug et al., 2004). Waste skin, scal and bone for fish processing are more than

30% and for canned fish are about 70% (Kittiphatatanabawon et al., 2005;

Geurard et al., 2001). In addition, according to Brody (1965) fish gelatin is

contain protein, he suggested that it can be as a permit for the low-income

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people to thrive on the cereal protein enrichment and fish gelatin also could

serve as a good outlet for the lower grades of gelatin.

In order to improve the usefulness of gelatin, the materials of gelatin treatment

can be modified. One of the ways is by manipulating the characteristics of

gelatin by addition of salts (Elysee-Collen and Lencki, 1996). Fish gelatin

properties can be modified by addition of coenhancer like salts, glycerols,

variation of pH and in combination of other ingredient such as sucrose (Koli et

al., 2011; Sarebia et al., 2002). Ashgar and Hanrickson (1982) stated that saline

ion will cause the collagen to interact with water molecules and folding

indirectly. In addition, when the fish skins have been washing with NaCl and

KCI at 0.8 M, it will result in a higher gelling ability and stability on fish gelatin

(Gimenez et al., 2005). Choi and Regenstein (2000) also stated that melting

point of gelatin decreased linearly as the concentration of NaCl went up to 14%.

Fish gelatin were more sensitive to NaCl concentration because NaCl is able to

break both of hydrophobic and hydrogen bonds. Thus preventing the

stabilization of the gel junction sites, either by prevent hydrogen bond formation

or by modify the structure of liquid water (Finch et al. 1974).

In most cases, increasing gel strength of a gelatin gel is accompanied by an

increased melting point (Veis, 1964). Gomez-Guillen and Montero (2001) also

reported a procedure for extracting gelatin with high gelling capacity from fish

skins based on mild acid pre-treatment for collagen swelling by extraction in

water at temperature 45ºC and the process take about 24 hours. The fish gelatin

stable at pH of 4 to 8 but will decrease at below pH 4 and above pH 8 (Choi and

Regenstein, 2000).

Naftalian and Symons (1974) suggested by adding sucrose to the gelatin

solution, it will increase the gel strength and melting point. It is due to the fact

that sucrose will stabilise hydrogen bonding (Naftalian and Symons, 1974).

Abbey et al. (2008) also suggested by adding flour, the melting point is

increasing. The changes in gelation temperature when fish gelatin was mixed

with cassava starch and melting point close to that of mammalian gelatin.

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2.5 Differential Scanning Calorimetry, rheometer, and chromameter

Differential Scanning Calorimetry (DSC) is a technique which is part of group

of technique called Thermal Analysis (TA). Differential Scanning Calorimetry

made up of a furnace for heating or cooling the sample at a controlled rate and a

selective transducer to monitor changes in the substance. The transducer can be

thermocouple to heat flow. A balance is connected to monitor to measure the

weight changes. The transducer generates a voltage signal which is amplified on

disk along with direct temperature response from the sample and recorded on a

printer (Gill, 1984).

Differential Scanning Calorimetry is particularly suitable for analysis of food

system because they are often subjected to heating or cooling process.

Differential Scanning Calorimetry is used to measure the temperature and heat

flows associated with phase transition in materials. Such measurement can

provide both quantitative and qualitative information concerning physical and

chemical changes, it involved the endothermic (energy consuming) and

exothermic (energy producing) process, or changes in heat capacity (Henssen,

2011).

Viscosity of polymer solution depends on the concentration and size of the

dissolved polymer. By measuring the solution viscosity we should be able to get

an idea about molecular weight. Rheometer is the instrument used to measure

force when it is applied to the sample or liquid and resulted in suspension or

slurry flows. It is used for those fluids which cannot be defined by a single value

of viscosity. It base on Newtonian and non-newtonian fluid. A Newtonian fluid

is one in which the viscosity is dependent of the shear rate. In Newtonian fluid

all the energy goes into sliding molecules by each other. In non-newtonian

fluids, the shear stress/strain rate relation is not linear (Anon, 2011).

The chromameter is a tool for precise and objective assessment of surface

colour. Data output, in the form of L*, a*, b* color coordinate system is used for

different studies pertaining to skin colour. L* values (darkness/lightness) are

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usefull in evaluating and quantifying the tanning response. The a* values

(red/green) are valuable for quantifying the degree of erythema (Muizzuddin et

al., 1990).

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CHAPTER 3

MATERIALS AND METHODS

3.1 Material

All samples were received from Department of Fish Processing Technology

College of Fisheries, Mangalore, India. These included the reference sample

which was the commercial gelatin origin from cow (bovine gelatin) and other

fish gelatins made from different types and part of fishes. The fishes used were

origin from India’s marine. They are Catla catla (Thaila), cirrhinus mrigala

(Mori), Labeo rohita (Rohu), and Cyprinus carpio (Gulform) (Sumaira, 2009).

All the fish gelatins were labeled as in Table 3.1.

Table 3.1 Type of gelatins

Sample of gelatin Label

gelatin standard (commercial) GA

skin of Catla catla GB

skin of Cirrhinus mrigala GC

skin of Labeo rohita GD

skin of Cyprinus carpio GE

air bladder of Catla catla GF

air bladder of Cirrhinus mrigala GG

bone of Cirrhinus mrigala GH

bone of Catla catla GI

bone of Labeo rohita GJ

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3.2 Analysis of gelatin

The melting point for all received samples were measured using Differential

Scanning calorimetry (DSC), the viscosity of gelatin was measured using

rheometer for sample GD and GE, and lastly, the colour measurements were

carried out using Chromameter for sample GA, GF, GG, GH, and GI.

3.2.1 Determination of melting point

The analyse of all samples, by method from Cheow et. al., (2007) were used a

Differential Scanning Calorimetry, Pyris Diamond DSC, (Perkin Elmer

Instruments, Norwalk, USA). The DSC was calibrated for temperature and

baseline using indium as standard. The samples were diluted to 6.67% (w/v)

using distilled water and weighed in order of 10mg (± 0.1mg) in a precision

balance (Sartorius, CP225D, Goettingen, Germany) and was placed in a

hermetically sealed aluminum pan. The pan was subjected to and heat at

5ºC/min between 5 and 60ºC and cooled back to 5ºC, and in inert atmosphere

(100ml/min of N2). All analyses were made in triplicates. Heat absorbed or

released by the sample resulted in an endothermic or exothermic peak as a

function of temperature. The temperature reached when half of the sample was

denatured was referred to as the transition temperature (Tm). It was measured at

the tip of the peak.

3.2.2 Viscosity measurement

Viscosity of sample was measured using rheometer, Physica Model No. MCR

300 (Physica Messtechnik GmbH, Darmstadt, Germany), and used CC27

concentric cylinder cup geometry with diameter gap is 1mm. the heating

temperature was controlled by peltier heat pump. The temperature used from

40ºC to 5ºC with rate of 1C/min and shear rate at 50 1/s (d(gamma)/dt). A graph

and value of viscosity were used to determine the effect of temperature on the

viscosity of gelatin.

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