Test for efficacy of pasteurization of milk is?
|A||Methylene blue test|
|B|| Phosphatase test|
|D|| Nitric Acid test|
Tests Performed on milk
Test performed on pasteurized milk
a. Phosphatase test: raw milk contains phosphatase which is destroyed on heating
b. Standard plate count: a limit of 30,000 bacterial count per ml
c. Coliform count: coliforms be absent in 1 ml of milk
Methylene blue reduction test
Indirect method for detection of microorganism in milk.
Carried out on milk accepted for pasteurization.
Methylene blue is added to 10 ml milk and sample is held at 37 degree C until blue color has disappeared.
Milk that remains blue longer is good quality.
Bacteria growing in the milk bring about a decrease in colour.
Cheap and time saving.
Kills 90% of bacteria including more heat resistant tubercle bacillus and Q fever organism
It doesn’t kill thermoduric bacteria or the bacterial spores.