I wish to express my deep gratitude and sincere thanks to the Principal, Raji Jayaprasad, Aditya Birla public school, Kovaya for her encouragement and for all the facilities that she provided for this project work.

I sincerely appreciate this magnanimity by taking me into her fold for which I shall remain indebted to her. I extend my hearty thanks to Mr. B. D. Kotwani, chemistry teacher, who guided me to the successful completion of this project.

I take this opportunity to express my deep sense of gratitude for his invaluable guidance, constant encouragement, constructive comments, sympathetic attitude and immense motivation, which has sustained my efforts at all stages of this project work. I can’t forget to offer my sincere thanks to Mr. Pankaj Bajpayee & also to my classmates who helped me to carry out this project work successfully & for their valuable advice & support, which I received from them time to time.

7 0. 2 0. 7 0. 9 Protei ns(%) 3. 4 1. 4 3. 3 5. 5 om Fats (%) 3. 9 4. 0 4. 2 6. 5 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: Carbohydra tes (%) 4. 9 4. 9 4. 8 4. 5 E. c iC BS Ca2+-Caesinate + 2CH3COOH(aq)>Caesin+ (CH3COO)2Ca E. c 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. These micelles have negative charge and on adding acid to milk the negative charges are neutralized. om AIM iC BS E. c om To study the quantity of Casein in different samples of milk. 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 iC BS E. c om 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 iC BS E. c om iC BS E. c om 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.

PROCEDURE 1. A clean dry beaker has been taken, followed by putting 20 ml of cow’s milk into it and adding 20 ml of saturated ammonium sulphate solution slowly and with stirring. Fat along with Caesin was precipitate out. 2. The solution was filtered and transferred the precipitates in another beaker. Added about 30 ml of water to the precipitate. Only Caesin dissolves in water forming milky solution leaving fat undissolved. iC BS E. c om 3. The milky solution was heated to about 40oC and add 1% acetic acid solution drop-wise, when casein got precipitated. iC 6.

The experiment was repeated with other samples of milk. BS 5. Weighed the dry solid mass in a previously weighed watch glass. E. c 4. Filtered the precipitate, washed with water and the precipitate was allowed to dry. om OBSERVATIONS Volume of milk taken in each case. ml Name of Weight of milk Caesin Cow milk Buffalo milk Goat milk Sheep milk = % of Caesin iC BS E. c om CONCLUSION Different samples of milk contain different percentage of Caesin. iC BS E. c om.

REFERENCES ? WEBSITES: ? www. icbse. com iC BS E. c om Comprehensive Practical Chemistry; Laxmi Publications.