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
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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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