Effects of high pressures combined with moderate temperatures on the rennet coagulation properties of milk

The effects of milk pressurization (100-400 MPa) at different temperatures (25-60 degrees C) on the denaturation of whey proteins, rennet coagulation time, wet cheese yield and enzymatic phase of coagulation have been investi gated. The results indicated that there is a synergistic effect between pre ssure and temperature on the biochemical properties of milk. Pressurization at 40 degrees C delayed coagulation time and impaired gel strength, althou gh protein and water retention in the curd were improved as compared with m ilk pressurized at 25 degrees C. The use of temperatures higher than 40 deg rees C adversely affected milk coagulation. The combined application of hig h pressures and moderate temperatures was found to increase the extent of b eta-lactoglobulin denaturation over treatments at 25 degrees C, and pressur ization at 50 degrees C induced denaturation of alpha-lactalbumin. Enhanced whey protein denaturation is supposed to be responsible for hindering the enzymatic hydrolysis of kappa-casein, in particular that of the glycosylate d forms. (C) 1998 Elsevier Science Ltd. All rights reserved.