Which post-pasteurization test indicates contamination after processing?

• A. Phospatase (effective pasteurization)
• B. Antibiotic (allergies/sensitivity)
• C. Coliforms (indicates contamination)
• D. Bacterial limits (quality/safety testing)

Answer: (C)

Post-pasteurization contamination is detected most specifically by testing for coliforms. Coliforms are indicators of environmental or fecal contamination that can occur after the product has been pasteurized. If they appear in a pasteurized product, it means something went wrong after processing—such as insufficient sanitation, post-process contamination, or compromise in packaging or handling. This is why the presence of coliforms serves as a direct signal of contamination after processing.

In contrast, the phosphatase test checks whether pasteurization was effective: if the trace enzyme phosphatase remains active, it suggests heat treatment may have been inadequate, not post-process contamination. Antibiotic testing looks for drug residues to protect sensitive individuals, not for microbial contamination arising after processing. General bacterial limits measure overall microbial load but don’t pinpoint post-pasteurization contamination as clearly as coliform testing does.