Alkaline Phosphatase (ALP) Testing for Milk Pasteurization

Alkaline Phosphatase (ALP) Testing for Milk Pasteurization

Alkaline Phosphatase (ALP) is an enzyme that is naturally found in raw milk and is considered an indicator of proper milk pasteurization. The heat stability of Alkaline Phosphatase (ALP) is high compared to milk pathogens. Therefore, the enzyme can be considered an indicator in terms of product safety. However, the absence of ALP activity does not indicate that there is no pathogen in milk.

Factors affecting the reactivation of alkaline phosphatase;
- Storage temperatures above 30°C
- Increased magnesium salt concentrations
- Changes in pH

Reactivated alkaline phosphatase is commonly observed in UHT milk. Reactivation of ALP can be interpreted as improper pasteurization. At high ALP levels, it is not known whether it is of microbial or natural origin. Therefore, it is recommended to repeat the pasteurization process. If it does not decrease with repeated pasteurization, it is probably microbial ALP.