Question

Phosphatase test is used for checking

• A. Efficiency of sterilization
• B. Efficiency of separation of milk
• C. Detection of sugar in milk
• D. Efficiency of pasteurization

Hint:

A simple mnemonic to remember this is: {P}hosphatase test for {P}asteurization efficiency. Both start with 'P'. This is one of the most fundamental quality tests in a dairy.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The phosphatase test is a crucial quality control test in the dairy industry. It relies on the properties of an enzyme naturally present in raw milk.
Step 2: Detailed Explanation:
Raw milk contains an enzyme called alkaline phosphatase. The key property of this enzyme is that its resistance to heat is slightly greater than that of the most heat-resistant pathogenic bacteria found in milk (e.g., Coxiella burnetii).
The time-temperature combinations used for pasteurization (e.g., 63°C for 30 minutes or 72°C for 15 seconds) are specifically designed to destroy all pathogens. Conveniently, these conditions are also sufficient to completely inactivate the alkaline phosphatase enzyme.
Therefore, if a sample of pasteurized milk is tested and found to have no active phosphatase, it is considered to have been properly pasteurized. If the test is positive (phosphatase is active), it indicates either under-pasteurization or post-pasteurization contamination with raw milk.
The other options are incorrect:
Sterilization uses much higher temperatures and is checked by testing for sterility (absence of all microorganisms).
Separation efficiency is checked by measuring the fat content in the skim milk.
Sugar is detected by specific chemical tests.
Step 3: Final Answer:
The phosphatase test is used to check the efficiency of pasteurization.