Step 1: Understanding the Concept:
Pasteurization is a mild thermal process designed to destroy pathogenic microorganisms in milk.
To verify that the process was successful without waiting for microbial culture results, processors use natural milk enzymes as indicators.
Detailed Explanation:
Alkaline Phosphatase (ALP) is a hydrolase enzyme naturally present in raw milk.
- ALP has a heat-resistance profile that is slightly greater than that of Coxiella burnetii, which is the most heat-resistant, non-spore-forming pathogen commonly found in raw milk.
- Consequently, if pasteurization conditions (e.g., $63\text{ }^\circ\text{C}$ for $30\text{ mins}$ or $72\text{ }^\circ\text{C}$ for $15\text{ secs}$) are sufficient to denature and inactivate ALP, they are also guaranteed to have destroyed all vegetative pathogens.
- The phosphatase test measures residual ALP activity in pasteurized milk. A negative result confirms adequate pasteurization, while a positive result indicates under-pasteurization or contamination with raw milk.
Step 2: Final Answer:
Alkaline phosphatase is the standard enzyme marker used to test milk pasteurization.