MPPSC 2021 Prelims Paper-I · Question 10 of 100

Correct — D, All of the above (per the official MPPSC key). The alkaline phosphatase test is best established for milk: alkaline phosphatase, naturally present in raw milk, is destroyed by correct pasteurisation, so a positive result signals under-pasteurised or raw-milk-adulterated milk. The official MPPSC answer key marks the umbrella option (d) as correct, so this card follows the official key; in standard food science the test's documented application is milk-specific.

• (a)Milk — The genuine, best-documented use of the test is verifying milk pasteurisation; the official MPPSC key, however, marks the umbrella option (d) rather than milk alone.
• (b)Tea — Per the official MPPSC key the credited answer is the umbrella option (d), not this single choice.
• (c)Water — Per the official MPPSC key the credited answer is the umbrella option (d), not this single choice.

The (alkaline) phosphatase test is an enzyme-based quality-control assay best documented in dairy science: it detects residual alkaline phosphatase activity in milk, which correct pasteurisation destroys. A positive colour reaction (via a reagent that turns yellow in the presence of active phosphatase) flags milk that was under-pasteurised or later contaminated with raw milk.

Most students only know the milk-pasteurisation fact and stop at option (a); the trap in state-PSC papers is that the official key sometimes credits the broader 'All of the above' option, crediting the same assay technique as a general quality-testing tool rather than a milk-only test. Always read every option before committing to the narrowest familiar answer.

• Alkaline phosphatase is a milk enzyme destroyed by correct pasteurisation — its presence signals under-pasteurised or raw-milk-adulterated milk
• Detected via a colour-change reaction, read with a comparator, proportional to residual enzyme activity
• The best-documented and most rigorously verified application of the test is milk pasteurisation control
• A rapid, low-equipment lab check favoured for quick quality-control screening

• Picking only 'Milk' because it is the best-known application and stopping there without reading the umbrella option
• Confusing the phosphatase test with other milk tests like MBRT or the COB (Clot-on-Boiling) test

MPPSC often tests applied food-science/lab-test facts as single-line recall — read every option carefully, since state keys sometimes credit the broadest option.

No directly related past PYQ was found.

• practice — not a real PYQ

  The alkaline phosphatase enzyme naturally present in raw milk is destroyed by:

  • (a)refrigeration
  • (b)correct pasteurisation
  • (c)homogenisation
  • (d)adding preservatives

  Answer(b) correct pasteurisation — its absence after processing confirms proper pasteurisation.

• practice — not a real PYQ

  Which of the following is a rapid test used to check whether milk has been adequately pasteurised?

  • (a)Clot-on-Boiling (COB) test
  • (b)Methylene Blue Reduction Test (MBRT)
  • (c)Phosphatase test
  • (d)Fat/SNF test

  Answer(c) Phosphatase test — checks for residual alkaline phosphatase activity as an index of pasteurisation efficiency.