ACKNOWLEDGEMENT

I would like to express my sincere gratitude to my

Chemistry mentor Miss Deepika Arora for their

vital support, guidance and encouragement without

which this project would not have come forth

from my side.

Special thanks of mine goes

to my colleagues who helped me a lot in completing

the project by giving interesting ideas, thoughts &

made this project easy and accurate. I wish to

thanks my parents for their undivided support &

interest who inspired me & encouraged me to go

my own way, without which I would be unable to

complete my project. And at last by no means

the least I would thank to God who made all the

things possible.

Ravi baghel

CONTENTS

INTRODUCTION

AIM

VALUE OF MILK AS FOOD

REQUIREMENTS

THEORY

PROCEDURE

OBSERVATION TABLE

CONCLUSION

BIBLIOGRAPHY

INTRODUCTION

Milk is a complete diet as it contains proteins,

carbohydrates, minerals, fats, vitamins and water in it.

Casein is the major protein constituent of present in the

milk and is a mixed phosphor-protein.

Casein has isoelectric pH of about 4.7 and can be easily

separated around this pH. It readily dissolves in dilute

acids and alkalis.

Casein is present in milk as calcium-caseinate in the form

of micelles. These micelles have negative charge. On

adding acids to milk the negative charges are neutralized.

AIM To study the quantity of Casein in different

samples of milk.

MILK

Milk is the whit fluid produced by the female of warm-blooded

animals for feeding her young ones. Animals that produce milk

directly gives birth to their offspring are called mammals.

In mammals the blood is pumped from the heart to the mammary

glands. The mammary glands are able to separate different

substances from the blood and combine them to make milk.

Milk has been called as nature’s most perfect and complete food. It

provides all the nutrients, which are required by the human babies

and other young mammals need for the growth and development.

Value of Milk as Food

Cow’s milk contains about 87% of water and 13% of solids. These

solids contain nutrients of milk.

Nutrients of milk

Our body needs five kinds of nutrients daily for our good health,

growth, development, and replacement of worn out tissues. These

nutrients are required by our body to get energy to perform various

metabolic activities in daily life. These nutrients are:

Carbohydrates

These are the major source 0f energy for our body. Carbohydrates

are also called Polyhydroxyl aldehyde or Polyhydroxyl ketone.

Carbohydrates content of milk is mainly lactose of milk sugar. In

addition to provide energy, lactose helps the body to absorb

minerals, calcium, and phosphorus in milk. Our bones and teeth are

largely consisting of these minerals. Lactose also gives sweetness

to milk.

Fats

Like carbohydrates fats also provides energy. They also supply

certain fatty acids that our body must have. Fat give milk its rich

flavor. Milk fat contains vitamins and several other substances.

One of these substances is carotene which our body converts into

vitamin-A. Milk fat appears as tiny globules.

Minerals

They help the body to grow and remain healthy. Calcium and

phosphorus is the most important mineral of milk. In fact, milk is

the chief food source of calcium. Other minerals in milk include

potassium, odium, sulphur and small amount of aluminium,

copper, iron, iodine, manganese and zinc.

Proteins

Like minerals help the body and maintain it, they also supply

energy. The protein contains all required amino acids for building

blood and tissue. Only egg protein and the proteins in some meat

have higher food value than milk proteins content of milk.

Vitamins

These are essential for growth maintaining tissue and prevention

of such diseases night blindness, beriberi, scurvy and rickets due to

deficiency of vitamin-A, vitamin-B, vitamin-C, and vitamin- D. Milk

provides more vitamins and in larger amount then most of the

other natural foods. Milk is an excellent source of vitamin-A and B2

and a good source of vitamin-B1. Other vitamins include C, K, E, B6,

B12 and Niacin. Milk also has vitamin-D the quantity is very low. In

some countries, diaries add extra vitamin to milk.

All mammals contain the same nutrients but these nutrients are

not at all identical in kind or in quantity. Compared with cow’s

milk, for example, the milk from a water buffalo has 3 times as

much as protein but three quarters the amount of sugar. Human

milk has fewer proteins and minerals than cow’s milk but contains

1.5 times more sugar.

In almost every country with dairy industry, whole milk is sold, as

food must meet certain standards most countries insist that whole

milk should contain at least 3.0% milk fat and up to 8.5% non fat

milk solid. Some require a higher percentage of about 3.5% milk

fat, 5.0% lactose, 3.5% proteins and 0.7% minerals. The percentage

differs between individual cow breeds. The quantity and

composition of milk also depends on what a cow feed and how the

animal is cared.

Milk is a complete diet as it contains in its Minerals,

Vitamins Proteins, Carbohydrates, Fats And Water. Average

composition of milk from different sources is given below:

Source of Milk

WATER (%)

MINERAL (%)

PROTEINS (%)

FATS (%)

CARBOHYDRATES (%)

COW 87.1 0.7 3.9 3.9 4.9

HUMAN 87.4 0.2 4.0 4.0 4.9

GOAT 87.0 0.7 4.2 4.2 4.8

SHEEP 82.6 0.9 5.5 6.5 4.5

Caesin is a major protein constituent in milk & is a mixed

phosphor-protein. Casein has isoelectric pH of about 4.7 and

can be easily separated around this isoelectric pH. It readily

dissolves in dilute acids and alkalies. Casein is present in milk

as calcium caseinate in the form of micelles.

REQUIREMENTS

> Beakers (250 ml)

> Filter-paper

> Glass rod

> Weight box

> Filtration flask

> Buchner funnel

> Test tubes

> Porcelain dish

> Different samples of milk

> 1 % acetic acid solution

> Ammonium sulphate solution

THEORY

Natural milk is an opaque white fluid Secreted by the

mammary glands of Female mammal . The main

constituents of natural milk are Protein, Carbohydrate,

Mineral Vitamins, Fats and Water and is a complete

balanced diet. Fresh milk is sweetish in taste. However ,

when it is kept for long time at a temperature of 5 degree it

become sour because of bacteria present in air. These bacteria

convert lactose of milk into lactic acid which is sour in

taste. In acidic condition casein of milk starts separating

out as a precipitate. When the acidity in milk is sufficient

and temperature is around 36 degree, it forms semi-solid

mass, called curd. Casein is present in milk as calcium

caseinate in the form of micelles. These micelles have

negative charge and on adding acid to milk, the negative

charges are neutralized.

Casein

Casein (/ˈkeɪs.ɪn/ or /ˈkeɪˌsiːn/, from Latin caseus,

"cheese") is the name for a family of related phosphoproteins

(αS1, αS2, β, κ). These proteins are commonly found in

mammalian milk, making up 80% of the proteins in cow

milk and between 20% and 45% of the proteins in human

milk. Casein has a wide variety of uses, from being a major

component of cheese, to use as a food additive, to a binder for

safety matches. As a food source, casein supplies amino

acids, carbohydrates, and the two inorganic elements

calcium and phosphorus.

Composition

Casein contains a fairly high number of proline residues,

which do not interact. There are also no disulfide bridges. As

a result, it has relatively little tertiary structure. It is

relatively hydrophobic, making it poorly soluble in water. It

is found in milk as a suspension of particles called "casein

micelles" which show only limited resemblance with

surfactant-type micellae in a sense that the hydrophilic

parts reside at the surface and they are spherical. However,

in sharp contrast to surfactant micelles, the interior of a

casein micelle is highly hydrated. The caseins in the

micelles are held together by calcium ions and hydrophobic

interactions. Any of several molecular models could account

for the special conformation of casein in the micelles. One of

them proposes the micellar nucleus is formed by several

submicelles, the periphery consisting of microvellosities of

κ-casein. Anoher model suggests the nucleus is formed by

casein-interlinked fibrils. Finally, the most recent model.

proposes a double link among the caseins for gelling to take

place. All three models consider micelles as colloidal

particles formed by casein aggregates wrapped up in soluble

κ-casein molecules.

The isoelectric point of casein is 4.6. Since milk's pH is 6.6,

casein has a negative charge in milk. The purified protein is

water insoluble. While it is also insoluble in neutral salt

solutions, it is readily dispersible in dilute alkalis and in

salt solutions such as sodium oxalate and sodium acetate.

.

Procedure • Take a clean dry beaker, put into it 20cc of goat’s milk and add 20

ml of saturated ammonium sulphate solution slowly and with

stirring. Fat along with casein will precipitate out.

• Filter the solution and transfer the precipitates in another beaker.

• Add about 30 ml of water to the precipitate.

• Only casein dissolves in water forming milky solution leaving fat

undissolved.

• Heat the milky solution to about 40°C and add 1% acetic acid

solution drop wise, when casein gets precipitated.

• Filter the ppt., wash with water, and let the ppt. dry.

• Weigh the dry solid mass in a previously weighed watch glass.

• Repeat the experiment with other samples of milk.

Observation Table If an acid is added to milk, the negative charge are neutralized and

the neutral protein precipitated out.

Ca+2 (Casemated) + 2CH3 COOH(aq) = Casein(s)+(CH3COO)2

Ca (aq)

Volume of milk taken in each case = 20 ml.

CONCLUSION

Different samples of milk contain different percentage of Caesin.

BIBLIOGRAPHy

www.google.com

www.wikipedia.com

www.icbse.com

www.seminarprojects.com