Chemistry Project Report
Study of Quantity of Casein Present in Various Samples of Milk
Student of XII-Science (Chemistry)
Vikram Jeet Mallick
Submitted to :
Lecturer in Chemistry
Sr. Sec. School
This is certified that the chemistry project report entitled “A project on the study of quantity of casein in different samples of milk” submitted for partial fulfillment of XII Sc. Practical examination in the subject of Chemistry embodies a record of original study carried out by student under my Supervision.
This project in my opinion is completed and is suitable for presentation. Lecturer in Chemistry.
(e) Result and discussion
Milk is a white liquid secreted by the mammary glands of female cows, buffaloes etc. It is a food of exceptional inters probability. Milk is the most nutritious food found in nature. That is why it is widely consumed both in its natural forms and as diary product like butter, cheese etc.
Milk contains vitamins, proteins, carbohydrates and the major milk protein casein are found only in milk and nowhere else in nature. The Composition of casein in milk is not constant. It depends upon the source of milk. Caesin 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. Ca Ca2+-Caesinate + 2CH3COOH(aq)→Caesin + (CH3COO)2
The protein, casein, existent, milk as the calcium salt, calcium casein etc. The salt has a complex structure and form micelles. These micelles have negative charges on the outer surface.
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
Different Samples of Milk
10% Acetic acid
Measure 20-ml, of a milk sample with the help of measuring cylinder and transfer into a clean 250ml. beaker.
Make the volume of milk to about 35ml, by adding water and warm the mixture to about 40 c.
Add to the warm mixture drowse and with constant stirring 10% acetic acid unit the precipitation is completed.
Stir the mixture for another 10 minutes or till the precipitated casein forms a large amorphous mass.
Filter the casein precipitate.
Wash thoroughly with water, dry foils between folds of filter paper and then in air for 1-2 days weight the dry solid so obtained.
Similarly, determine the amount of casein in other samples of milk.
Volume of Milk Taken in each case = 20ml.
Quality of Milk
Weight of casein
percentage of casein
Therefore if an acid is added to milk the negative charge are neutralized and the neutral protein precipitated out.
Ca+2 (casemated) +2 CH3 COOH (aq)
Casein + (CH3 COO)2 Ca
Results and Discussion
Different samples of milk contain different percent of casein and the casein contents in amul brand are appreciable. At present amul is the best bend of milk available in the market.
Laboratory manual in chemistry Class XII by B.Bhushan
Advanced organic practical chemistry for P.G. Students & by O.P. Agarwal. Internet Source : www.google.com www.yahoo.com