Milk catalase activity as an indicator of thermization treatments used in the manufacture of cheddar cheese.

Pilot-scale studies were carried out to determine the effect of different heat treatments on catalase activity during the manufacture and maturation of Cheddar cheese. Three trials were conducted to monitor catalase activity using disk flotation and polarographic methods. Cheese was manufactured from raw milk and from milk that had been treated at 60, 65 and 72 degrees C for 16 s using a high temperature, short time heat exchanger. Catalase activity was also determined in samples of commercial milk and in samples of mild, medium, sharp, and extra sharp Cheddar cheeses obtained from different manufacturers in order to verify that the enzyme could be used as an indicator of the type of heat treatment applied to cheese milk. Catalase activity was present in cheese made from raw milk but was only present at low concentrations in cheese manufactured from thermized milk. However, high catalase activity was observed in commercial samples of sharp and extra sharp Cheddar cheese that was apparently due to the growth of catalase-producing yeasts in the cheese during maturation.