This is my investigatory class 12 chemistry project on the topic "study of quantity of casein present in various milk samples"

1. CHEMISTRY PROJECT
STUDYOF
QUANTITYOFCASEIN
PRESENT IN
DIFFERENT SAMPLES
OF MILK
BY PALLAVI SARIN
CLASS:
SUBJECT: CHEMISTRY
SESSION:
SCHOOL:
ROLL NO.

2. CERTIFICATE
This is to certify that XXXX XXXX of class XXX , XXXXX
School, XXXXXX has successfully completed the
investigatory project titled “STUDY OF QUANTITY OF
CASEIN PRESENT IN DIFFERENT SAMPLES
OF MILK” under the guidance and supervision of Ms.
XXXXX XXXXX (Chemistry Teacher) during the year
2XXX-2XXX in the partial fulfillment of the Chemistry
practical examination conducted by the CBSE. It is
further certified that this project is the individual and
bonafide work of the candidate. This project in my
opinion is completed and ready for presentation.
EXTERNAL EXAMINER SUBJECTTEACHER
(Ms. XXXXX XXXXX)

3. ACKNOWLEDGEMENT
I would like to express my special thanks of gratitude to my
teacher Ms. XXXXXX XXXXXX as well as our principal Ms.
XXXX XXXX who gave me the golden opportunity to do this
wonderful project on the topic “STUDY OF QUANTITY OF
CASEIN PRESENT IN DIFFERENT SAMPLES
OF MILK”, which also helped me in gaining knowledge
about the topic and in learning new things. I take this
opportunity to express my deep sense of gratitude for her
invaluable guidance, constant encouragement, constructive
comments, sympathetic attitude and immense motivation,
which has sustained my efforts at all stages of this project
work. I am really thankful to them.
Secondly I would also like to thank my parents and friends
who encouraged me and supported me to do the project to
the best of my ability.

4. INDEX
1. AIM
2. APPARATUS AND CHEMICALS
REQUIRED
3. PRINCIPLES APPLIED AND
THEORY
4. PROCEDURE
5. OBSERVATION
6. RESULT
7. PRECAUTIONS
8. BIBLIOGRAPHY

5. AIM
•TO STUDY THE QUANTITY
OF CASEIN PRESENT IN
DIFFERENT SAMPLES OF
MILK.

6. APPARATUSAND
CHEMICALS REQUIRED
APPARATUS
• 250ML BEAKERS
• FUNNEL, GLASS ROD
• PORCELAIN DISH
• CHEMICAL BALANCES
• TEST TUBES
• FILTRATION FLASK
• BURNER
CHEMICALS
• DIFFERENT SAMPLES OF MILK
• 1% OF ACETIC ACID SOLUTION
• SATURATED AMMONIUM SULPHATE SOLUTION

7. THEORY
• Casein is the name of related phosphoproteins.
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. The most
common form of casein is sodium caseinate.
• As a food source, casein supplies for amino acids,
carbohydrates and two inorganic elements, calcium
and phosphorus.
• Casein contains a fairly high number of proline
residues, which do not interact. There are also no
disulfide bridges. As a result hydrophobic, making it
poorly soluble in water. It is found in milk as a
suspension of particle called “casein micelles” which
show only limited resemblance with surfactant-type
micelles 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.

8. • The caseins in the micelles are held together by calcium
ions and hydrophobic interactions. Several models
account for the special conformation of casein in the
micelles. One of them proposes the micellar nucleus is
formed by several sub micelles, the periphery consisting
of K-casein. Another 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 K-casein molecules.

9. • 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.

10. • 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 aqueous sodium
oxalate and sodium acetate.
• The enzyme trypsin can hydrolyze a phosphate-
containingpeptone. It is used to form a type of organic
adhesive.
• Ca2+-Caseinate + 2CH
3
COOH(aq. )---- Casein(s)+ (CH
3
COOH)
2
Ca

11. • Milk is a nutrient-rich, white liquid food produced by the
mammary glands of mammals. It is the primary source of
nutrition for infant mammals (including humans who are
breastfed) before they are able to digest other types of food.
Early-lactation milk contains colostrum, which carries the
mother's antibodies to its young and can reduce the risk of
many diseases. It contains many other nutrients including
protein and lactose. Interspecies consumption of milk is not
uncommon, particularly among humans, many of whom
consume the milk of other mammals. As an agricultural
product, milk, also called dairy milk, is extracted from farm
animals during or soon after pregnancy. Dairy farms produced
about 730 million tonnes of milk in 2011, from 260 million
dairy cows. India is the world's largest producer of milk, and is
the leading exporter of skimmed milk powder, yet it exports
few other milk products. The ever increasing rise in domestic
demand for dairy products and a large demand-supply gap
could lead to India being a net importer of dairy products in
the future.

12. • The United States, India, China and Brazil are the world's
largest exporters of milk and milk products. China and
Russia were the world's largest importers of milk and
milk products until 2016 when both countries became
self-sufficient, contributing to a worldwide glut of milk.
Throughout the world, more than six billion people
consume milk and milk products. Over 750 million people
live in dairy farming households. Milk as a whole
contains water, minerals ( Ca, K, Na and trace metals),
vitamins(A, D, K), carbohydrates, proteins and fats.The
proportion of these varies from source to source.
Average composition of milk from different sources is
given ahead.

13. SEPARATION OF CASEIN
• 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
are 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.

14. 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 slowly and with stirring.
Fat along with casein 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 casein dissolves in water
forming milky solution leaving fat undissolved.
• 3. The milky solution was heated to about 40° C and 1%
acetic acid solution drop-wise, when casein got
precipitated.
• 4. Filtered the precipitate, washed with water and the
precipitate was allowed to dry.
• 5. Weighed the dry solid mass in a previously weighed
watch glass.
• 6. The experiment was repeated with other samples of
milk.

15. OBSERVATIONTABLE
S.NO. TYPE OF MILK WEIGHTOF
CASEIN
PRESENT
PERCENTAGE
OF CASEIN (i.e.
g/100ml)
1. COW MILK 0.60 3.00%
2. GOAT MILK 0.55 2.75%
3. BUFFALO MILK 0.85 4.25%
4. AMUL MILK 0.75 3.75%
Volume of each milk sample is 20 mL.

16. RESULT
• According to our analysis of various samples of milk, we
conclude that:
• Cow milk contains 3.00 % casein
• Goat milk contains 2.75 % casein
• Buffalo milk contains 4.25 % casein
• Amul milk contains 3.75 % casein
• According to above results, we conclude that buffalo
milk is most beneficial for human beings.

17. PRECAUTIONS
• During filtration, press the casein formed.
• Use only the required amount of acid for complete
precipitation.
• Use only fresh milk.
• Use same amount of each sample for the experiment.

18. BIBLIOGRAPHY
• Google Images
• NCERT Chemistry Laboratory Manual Class XII
• www.chemistrystackexchange.com/
• https://en.wikipedia.org/wiki/Casein
• https://en.wikipedia.org/wiki/Milk
• https://www.slideshare.net/dineshpol/amount-of-
casein-in-milk