2014-2015
CHEMISTRY INVESTIGATORY PROJECT
ARPIT RANKA
XIl-A
ROLL NO. 18
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ACKNOWLEGEMENT
I would like to express my immense gratitude to my
chemistry teacher Mrs. Poonam Taneja, 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, Iwould like to thank my school mates who have
rendered and done this project along with me. Their support
made this project fruitful.
-ARPIT RANKA
CERTIFICATE
This is to certify that Mr. ARPIT RANKA (Roll No. -18),
student of class XII-A', S.D Jain Modern School Surat 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 2014-2015 under
the guidance of Mrs. Poonam Taneja.
School Stamp
Signature of Principal
Signature of external examiner
Signature of chemistry teacher
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OBJECTIVETo study the quantity of Casein present
in different samples of milk.
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INTRODUCTIONMilk 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 OF WATER
MILK
MINERALS
()
()
PROTEINS
FATS
)
()
CARBO-HYDRATES
()
Cow
87.1
0.7
3.9
4.9
Human
87.4
0.2
4.0
4.9
Goat
87
0-7
4.2
4.8
Sheep
82.6
0.9
6.5
4.5
Casein is the most predominant phosphoprote is found
in milk an cheese. When
coagulated with rennet, casein is
ometimes 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 surtactant-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.
ca-Caesinate+ 2CH,cOOH(aq)> Casein-(CH,COO),ca(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
and
fast-digesting whey protein,
of glutamine (post
extremely high
also
as
workout). Another reason it is used in bodybuilding, is
an
source
because of its anti-catabolic effect, meaning that casein
consumption inhibits protein breakdown in the body. Casein
frequently found in otherwise nondairy cheese substitutes
to improve consistency especially when melted.
AIM
To study quantity of casein in different samples of milk.
THEORYMilk contains 3 to 4% casein suspended in water in the
colloidal form. It is precipitated ina weakly acidic medium.
APPARATUS REQUIRED
Funnel, funnel stand, glass rod,filter paper,weight box,
test tubes, pestle and mortar.
CHEMICALS REQUIRED
() Different samples of milk.
(i) Saturated ammonium sulphate solution.
(ii) 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 2o ml saturated solution of ammonium sulphate slowly with
stiring. 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 3o ml distilled water. Casein
dissolves forming millky 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 = W,g
Weight of Casein isolated = W, 8
Percentage of casein Weight of Casein x 100
=
Weight of milk
S.no.
1.
Type of milk Volume of Weight Weight of
Buffalo's
Percentage of
casein
milktaken
of milk
Casein
(ml)
(W,8)
W, 8)
20
23.09
o.632
2.73%
milk
2.
Cow's milk
20
35.66
0.55
1.64%
3.
Goat's milk
20
23.09
0.77
3.67%
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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