Ratanjee Modern School
2022-2023
Chemistry Investigatory
Project
Submitted To:
Mr. Vijay Saxena Sir
Submitted by:
Pawan Dixit
XII-B
ACKNOWLEGEMENT
I would like to express my immense
gratitude to my chemistry teacher Mr. Vijay
Saxena , 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.
Certificate
This is to certify that Mr. Pawan Dixit
(Roll No. - 24) , student of class XII – ‘B’,
Ratanjee Modern School ,New Delhi has
successfully completed research in the
below given project under the heading
‘Study of amount of casein in different
milk samples’ during the academic
session 2022-2023 under the guidance
of Mr. Vijay Saxena.
Signature
Objective –
To study the quantity of Casein
present in different samples of
milk.
Introduction –
Milk is a complete diet as it contains proteins,
carbohydrates, fats, minerals, vitamins and water.
The average composition of milk from different
sources is given below:
SOURCE WATER MINERA PROTEI FATS CARBO-
OF MILK (%) LS NS (%) HYDRAT
(%) (%) ES
(%)
Cow 87.1 0.7 3.4 3.9 4.9
Human 87.4 0.2 1.4 4.0 4.9
Goat 87 0.7 3.3 4.2 4.8
Sheep 82.6 0.9 5.5 6.5 4.5
Casein is the most predominant phosphoprote is
found in milk an cheese. When coagulated with
rennet, casein is sometimes called Paracasein.
British terminology, on the other hand, uses the
term caseinogen for the uncoagulated protein and
casein for coagulated protein. As it exists in milk, it
is a salt of calcium.
Casein is not coagulated by heat. It is precipitated
by acids and by rennet enzymes, a proteolytic
enzyme typically obtained from the stomachs of
calves. The enzyme trypsin can hydrolyze off a
phosphate-containing peptone.
Casein consists of a fairly high number of praline
peptides, which do not interact. There are also no
disulphide bridges. As a result, it has relatively little
secondary structure or tertiary structure. Because
of this, it cannot denature. 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 some resemblance with
surfactant-type micellae in a sense that the
hydrophilic parts reside at the surface. The caseins
in the micelles are held together by calcium ions
and hydrophobic interactions. These micelles have
negative charge and on adding acid to milk the
negative charges are neutralized.
Ca2+ - Caesinate + 2CH3COOH(aq)
→ Casein+(CH3COO)2Ca(aq)
The isoelectric point of casein is 4.7. 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.
Applications:
In addition to being consumed in milk, casein in
used in the manufacture of adhesives, binders,
protective coatings, plastics (such as for knife
handles and knitting needles), fabrics, food
additives and many other products. It is
commonly used by bodybuilders as a slow-
digestive source of amino acids as opposed to
the fast-digesting whey protein, and also as an
extremely high source of glutamine (post
workout). Another reason it is used in
bodybuilding, is because of its anti-catabolic
effect, meaning that casein consumption
inhibits protein breakdown in the body. Casein
is frequently found in otherwise nondairy
cheese substitutes to improve consistency
especially when melted.
Aim –
To study quantity of casein in different
samples of milk.
Theory –
Milk contains 3 to 4% casein suspended
in water in the colloidal form. It is
precipitated in a weakly acidic medium.
Apparatus Required –
Funnel, funnel stand , glass rod , filter
paper, weight box , test tubes, pestle
and mortar
Chemicals Required –
(i) Different samples of milk.
(ii) Saturated ammonium sulphate
solution.
(iii) 1 % acetic acid solution.
Procedure –
1. Wash the beaker (250 ml) with the
distilled water and dry it.
2. Take 20 ml of buffalo’s milk in 250 ml
beaker and find its weight.
3. Add 20 ml saturated solution of
ammonium sulphate slowly with
stirring. Fat and casein will separate
out as precipitate.
4. Filter the above solution and transfer
the precipitate in another beaker.
5. Treat the above precipitate with 30 ml
distilled water. Casein dissolves
forming milky solution whereas fat
remains as such.
6. Warm the above contents of the
beaker to 40 - 45°C on a low flame.
Now, add 1% acetic acid solution drop
wise with stirring when casein gets
precipitated.
7. Filter the precipitated casein and wash
with distilled water and dry it.
8. Find the weight of dry precipitate.
9. Repeat the whole experiment with
cow’s milk, goat’s milk and sheep’s
milk.
Observations –
Volume of milk taken in each case = 20 ml
Weight of milk taken = W₁ g
Weight of Casein isolated = W₂ g
Percentage of casein = Weight of Casein x 100
Weight of milk
S.no. Type of Volume of Weight of Weight of Percentag
milk milk milk (W₁ Casein e of
taken g) (W₂ g) casein
(ml)
1. Buffalo’s 20 23.09 0.632 2.73%
milk
2. Cow’s 20 35.66 0.55 1.64%
milk
3. Goat’s 20 23.09 0.77 3.67%
milk
Result –
Different Samples of milk contains
different percentage of casein.
Highest percentage of casein is present
in Goat’s milk.
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.
Bibliography –
www.wikipedia.com
www.encyclopedia.com
www.caesine-pro.com
www.sciencejournals.com
www.icar.nic.in
www.zetascience.com
www.scribd.com
