Study of amount of casein in different samples of milk

2014-2015

Chemistry Investigatory Project

PRATYUSH SHARMA XII – ‘C’ ROLL NO. - 35 2014-2015

ACKNOWLEGEMENT I would like to express my immense gratitude to my chemistry teacher Dr. Shazia Ali , for the help and guidance she provided for completing the investigatory project. I also thank my parents who gave their ideas and inputs in making this Project. Most of all i thank our school management, for providing us the facilities and opportunity to do this project. Lastly, I would like to thank my school mates who have rendered and done this project along with me. Their support made this project fruitful.

- PRATYUSH SHARMA

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Certificate This is to certify that Pratyush Sharma (Roll No. 35) , student of class XII – ‘C’, Campion School Bhopal has successfully completed research in the below given project under the heading ‘Study of amount of casein in different milk sample’ during the academic session 2014-2015 under the guidance of Dr. Shazia Ali conducted by AISSCE, New Delhi.

Signature of external examiner

Signature of chemistry teacher

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STUDY OF AMOUNT OF CASEIN IN DIFFERENT SAMPLES OF MILK

MADE BY – Pratyush Sharma Class – XII – ‘C’ Roll no. – 35 School – Campion school Bhopal

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AIM

–

To study quantity of casein in different samples of milk.

APPARATUS AND CHEMICALS REQUIRED1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

BEAKER (2) FILTER PAPER CONICAL FLASK (2) TEST TUBE TEST TUBE HOLDER SPETULA GLASS ROD SATURATED AMMONIUM SULPHATE 1% ACETIC ACID FUNNEL DIFFERENT SAMPLES OF MILK

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THEORYMilk is a complete diet as it contains in its Minerals, Vitamins Proteins, Carbohydrates, Fats And Water. Casein 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. Ca2+-Caesinate +2CH3COOH(aq)-Caesein+(CHCOO)2Ca

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 Page 5 of 9

bacteria convert lactose of milk into lactic acid which is sour in taste. In acidic conditions casein of milk separate out as precipitate. When the acidity in milk is sufficient and temperature is around 36 degree, it forms curd.

PROCEDURE1. Take a clean beaker, 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 Casein will precipitate out. 2. Filter the newly formed solution and transfer it in another beaker. Add about 30 ml of water to the precipitate. Only Casein dissolves in water forming milky solution leaving fat undissolved. 3. Heat the milky solution to about 40 degree and add 1% acetic acid solution drop-wise, when casein get precipitated. 4. Filter the precipitate and keep it aside to dry . 5. Weigh the dry solid mass in a previously weighed watch glass. 6. Repeat the experiment with other samples of milk.

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OBSERVATIONS Volume of milk taken in each case = 20 ml S.no.

Type of milk

1. 2. 3. 4.

Cow Goat Buffalo Powder

Amount of Casein (In 20 ml milk) 0.62 0.56 0.66 0

Percentage of casein 3.1% 2.8% 3.3% 0%

RESULT – Amount of Casein in different samples of milk has been studied systematically.

PRECAUTIONS – 1. Handle apparatus and chemicals carefully. 2. Add ammonium sulphate solution very slowly. 3. Stir milk while adding chemicals. 4. Do not disturb milk after adding ammonium sulphate solution and wait some time for fat and casein to precipitate out. 5. Take the amount readings carefully with digital weighing machine only.

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