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Study of quantity of casein in milk
Chemistry SL (ST Thomas Higher Secondary School)
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CHEMISTRY
INVESTIGATORY
PROJECT
NAME- ............................
CLASS- XII SCIENCE
ROLL NOSUBJECT- CHEMISTRY
TOPIC-STUDY OF QUANTITY
OF CAESIN PRESENT IN
DIFFERENT MILK SAMPLES
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This is to certify that ................................................ of
class XII (Science) of Kendriya Vidyalaya
Birbhum has completed the Investigatory
Project in Chemistry titled “Study Of Quantity of
Casein present in Different Samples of Milk”
himself under the supervision and guidance of
Chemistry Teacher during the year 2018-19. The
progress of the project has been continuously
reported and has been
in my knowledge consistently
Signature of
Principal
Signature of External
Invigilator
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Signature of subject
Teacher
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First of all, I am deeply thankful to my Chemistry
teacher ............................................ for extending his valuable
a n d sch o la r ly g u id a n ce t h r o u g h o u t t h e p r ep a r a t io n
o f t h is p r o ject . I wish t o ext en d m y sin cer e t h a n ks t o
M r . .......................................................... r esp ect ed Pr in cip a l,
Ken d r iya Vid ya la ya Bir b h u m fo r h is co n t in u o u s
m o t iva t io n a n d m o r a l su p p o r t fo r co m p let in g t h e
wo r k.
I a m a lso t h a n kfu l t o a ll m y r esp ect ed t ea ch er s,
lib r a r y st a ff, o ffice st a ff a n d st a ff m em b er s o f t h e
Ch em ist r y La b o r a t o r y o f t h e sch o o l.
I a m a lso t h a n kfu l t o t h e t ea ch er s a n d st a ff
m em b er s o f t h e d ep a r t m en t o f Ch em ist r y fo r
ext en d in g t h eir h u m a n it a r ia n a n d sch o la st ic
a ssist a n ce in fin d in g o u t t h e so lu t io n s o f so m e q u er y
d u r in g m y wo r k.
La st b u t n o t h e lea st I a m in d eb t ed t o m y
fr ien d s, cla ssm a t es a n d p a r en t s fo r en co u r a g in g
a n d n ever let m e d o wn in m y co n fid en ce wh ile
co m p let in g t h e p r o ject .
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INTRODUCTION
What is Casein ?
Casein is the protein found in all mammals’ milk. Mammals
include cow, goat, sheep, yak, buffalo, camel and humans.
Milk is a complete diet as it contains minerals, vitamins,
proteins, Carbohydrates, Fats And Water . Average
composition of milk fro different sources is given below :
SOURCE
OF MILK
WATER
(%)
Cow
Human
Goat
Sheep
87.1
87.4
87
82.6
MINERAL PROTEIN
S
(%)
(%)
0.7
3.4
0.2
1.4
0.7
3.3
0.9
5.5
FATS
(%)
3.9
4.0
4.2
6.5
CARBOH
YDRATES
(%)
4.9
4.9
4.8
4.5
Casein in the most predominant protein in milk and is a mixed
phosphor protein. Casein has a isoelectric pH of about 4.7 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.
Ca 2 + -Caesinate + 2CH 3COOH(aq) - Caesein + (CHCOO)2 Ca
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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 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.
APPLICATIONS:
In addition to being consumed in milk casein is used in the
manufacture of adhesives, binders, protective coatings,
plastics(such as knife handles and knitting needles), fabrics,
food additives, and many other products.It is commonly used
by body builders as slow digesting whey proteins 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
non dairy substitutes to improve consistency especially when
melted.
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AIM :
To study quantity of casein in different samples of milk.
THEORY :
Milk contains 3% to4% casein suspended in water in colloidal form.It si
precipitated in 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.
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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.
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OBSERVATIONS :

Volume of milk taken in each
case
 20 ml

Weight of milk taken
 W1 g

Weight of Casein isolated
W 2 g

Percentage of casein =
Weight of casien
* 100
Weight of Milk
SL.NO
Type of
Milk
1
Buffalo’s
milk
Cow’s
milk
Goat’s
milk
2
3
Volume of
Milk Taken
(ml)
20
Weight of
Milk
( g)
23.09
Weight of Percentage
Casein
Of
( g)
Casein
0.632
2.73 %
20
35.66
0.55
1.64 %
20
23.09
0.77
3.67 %
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RESULT :
(i) Different Samples of milk contains different percentage
of casein.
(ii) 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 a dding 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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BIBLIOGRAPHY

www.wikipedia.com

www.encyclopedia.com

www.caesine-pro.com

www.sciencejournals.com

www.icar.nic.in

www.zetascience.com

www.scribd.com
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