Heat treatment of cheese milk

Abstract

Abstract Danbo 45+ was manufactured from milk subjected to heat treatment at 72, 80 or 90°C for 15, 30 and 60 s. The effect of heat treatment on the activity of plasmin in the resulting cheeses and the subsequent proteolysis of caseins during ripening were examined. This revealed that the plasmin activity decreased as the temperature and the holding time increased. In addition, the cheeses showed decreased digestion of β - and α s2 -caseins during ripening, which was explained by variations in plasmin activity. The digestion of para- κ casein was slightly affected by heat treatment, which may be explained by steric hindrance due to the formation of thermally induced complexes with whey proteins. The digestion of α s1 -casein, however, was unaffected by the heat treatment and probably results primarily from the action of residual rennet. It is suggested that the altered proteolytic digestion of casein during ripening of cheese manufactured from heated milk results from reduced plasmin activity in the cheese as a consequence of thermal inactivation of the plasminogen activation system and thermally induced interactions between the components of the plasminogen activation system and β -lactoglobulin.