Question:easy
The efficiency of pasteurisation of milk is assessed by which of the following tests?
The efficiency of pasteurisation of milk is assessed by which of the following tests?
Show Hint
Look for the heat-labile enzyme that disappears with proper heating.
Updated On: Jun 24, 2026
- Phosphatase test
- Methylene blue test
- Catalase test
- Oxidase test
Show Solution
The Correct Option is A
Solution and Explanation
To check whether milk has been pasteurised properly, we look for a heat-sensitive natural marker rather than counting bacteria. Alkaline phosphatase is normally present in raw milk and is destroyed at the same temperature-time conditions required to kill milk-borne pathogens. The phosphatase test searches for any leftover active enzyme: if none is found the test is negative, proving the milk was heated adequately and pasteurisation was effective; a positive test signals under-heating or contamination with raw milk. By contrast, the methylene blue reduction test grades the bacterial quality of milk, while catalase and oxidase tests are used to characterise bacteria. Thus pasteurisation efficiency is judged by the phosphatase test.
\[\boxed{\text{Phosphatase test}}\]
\[\boxed{\text{Phosphatase test}}\]
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