Test for Lactalbumin and Lactoglobulin in milk:

To perform the test for Lactalbumin and Lactoglobulin in milk, first we will extract filtrate of milk, and then we will carry out the test on this filtrate. To obtain filtrate of milk follows the below procedure.

Obtaining of filtrate from milk:
Procedure:

• Take 20 ml of milk in a beaker.
• Add 1% acetic acid drop by drop.
• Stir briskly till a white precipitate is formed.
• The precipitate consists of casein and fats.
• Filter through the filter paper.
• Re-filter if the filtrate is cloudy.
• The filtrate contains carbohydrate, lactalbumin, lactoglobulin and inorganic constituents.

Now we can perform the test for Lactalbumin and Lactoglobulin in milk.

Chemicals Required:

• Chlorophenol Red indicator.
• 2% Sodium carbonate (Na2CO3)
• Filtrate from milk

Procedure:

• Take 3 ml of filtrate in a test tube.
• Add one drop of Chlorophenol Red indicator.
• Then add 2% Sodium carbonate (Na2CO3) till the colour turns pink red.
• This indicates isoelectric pH.
• Boil solution for 3 minutes.
• Coagulum forms, which confirms the presence of lactalbumin and lactoglobulin.

Observation:

After boiling the solution for 3 minutes, coagulum forms which show that lactalbumin and lactoglobulin are present.

Note:

After performing this procedure, then filter this solution. Use the lactose, calcium and phosphate analysis.

Precautions:

• Before starting the whole process, Wash the apparatus before and after the experiment.
• Make sure the filter paper is clean before using it.
• Carefully handle all the chemicals in the lab.