Proteolysis During Cheese Manufacture and Ripening

Proteolysis in cheese can be divided into three phases: proteolysis in milk before cheese manufacture, the enzymatically induced coagulation of the milk, and proteolysis during cheese ripening. Extracellular proteinases from psychrotrophs may cause reduced cheese yields and off-flavors, but the problem does not appear to be significant at populations <106 cfu/ml. Proteinases from leucocytes may also reduce yields, but these are less active than bacterial proteinases. Plasmin (indigenous milk proteinase) causes significant hydrolysis of [-casein, especially in late lactation, but because most of this occurs prior to milking, yield losses due to plasmin activity (i. e. , via formation of proteose peptones) are largely unavoidable.