Milk is a white liquid secreted by the mammary secretory organs of female cattles. American bisons etc. It is a nutrient of exceeding inters chance. Milk is the most alimentary nutrient found in nature. That is why it is widely consumed both in its natural signifiers and as diary merchandise like butter. cheese etc.
Milk contains vitamins. proteins. saccharides and the major milk protein casein are found merely in milk and nowhere else in nature. The Composition of casein in milk is non changeless. It depends upon the beginning of milk. Caesin is a major protein component in milk & A ; is a assorted phosphor-protein. Casein has isoelectric pH of about 4. 7 and can be easy separated around this isoelectric pH. It readily dissolves in dilute acids and bases. Casein is present in milk as Ca caseinate in the signifier 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 Ca salt. Ca casein etc. The salt has a complex construction and signifier micelles. These micelles have negative charges on the outer surface.
In acidic status casein of milk starts dividing out as a precipitate. When the sourness in milk is sufficient and temperature is about 36 grade. it forms semi-solid mass. called curd
- 250-ml. beakerFiltrations flaskMeasuring CylinderGlass RodSpatulaChina DishDropperWeight BoreDifferent Samples of Milk10 % Acetic acid
- ProcedureMeasure 20-ml. of a milk sample with the aid of mensurating cylinder and reassign into a clean 250ml. beaker.
- Make the volume of milk to about 35ml. by adding H2O and warm the mixture to about 40 degree Celsiuss.
- Add to the warm mixture doze and with changeless stirring 10 % acetic acid unit the precipitation is completed.
- Stir the mixture for another 10 proceedingss or till the precipitated casein forms a big formless mass.
- Filter the casein precipitate.
- Wash exhaustively with H2O. dry foils between creases of filter paper and so in air for 1-2 yearss weight the dry solid so obtained.
- Similarly. find the sum of casein in other samples of milk.
Volume of Milk Taken in each instance = 20ml.Sample No.Quality of MilkWeight of caseinper centum of casein1.SARAS0. 603. 00 %2.PANCHAMRAT0. 653. 25 %3.AMUL0. 854. 20 %4.RATH0. 753. 70 %Therefore if an acid is added to milk the negative charge are neutralized and the impersonal protein precipitated out.
Ca+2 ( casemated ) +2 CH3 COOH ( aq )Casein + ( CH3 COO ) 2 Ca
Consequences and Discussion
Different samples of milk contain different per centum of casein and the casein contents in amul trade name are appreciable. At present amul is the best crook of milk available in the market.
- Laboratory manual in chemical science Class XII by B. BhushanAdvanced organic practical chemical science for P. G. Students & A ; by O. P. Agarwal. Internet Beginning: World Wide Web. Google. com World Wide Web. yokel. com.