Alkaline phosphatase activity in Penicillium roqueforti and in blue-veined cheeses.

The Penicillium roqueforti mold exhibits alkaline phosphatase activity. Therefore, blue mold-ripened cheeses made from properly pasteurized milk test positive for phosphatase. Because microbial phosphatases are considered to be more resistant to heat than is milk phosphatase, a statutory control test recommends the repasteurization of cheese at 66 degrees C for 30 min to inactivate selectively the native milk enzyme. However, because of thermal lability of Penicillium roqueforti phosphatase, this control test leads to confusion of the fungal enzyme with native milk alkaline phosphatase and does not confirm whether the milk used to make cheese has been pasteurized.