Effects of High Pressures Combined with Moderate Temperatures on the Rennet Coagulation Properties of Milk

Abstract

The effects of milk pressurization (100–400 MPa) at different temperatures (25–60°C) on the denaturation of whey proteins, rennet coagulation time, wet cheese yield and enzymatic phase of coagulation have been investigated. The results indicated that there is a synergistic effect between pressure and temperature on the biochemical properties of milk. Pressurization at 40°C delayed coagulation time and impaired gel strength, although protein and water retention in the curd were improved as compared with milk pressurized at 25°C. The use of temperatures higher than 40°C adversely affected milk coagulation. The combined application of high pressures and moderate temperatures was found to increase the extent of β-lactoglobulin denaturation over treatments at 25°C, and pressurization at 50°C induced denaturation of α-lactalbumin. Enhanced whey protein denaturation is supposed to be responsible for hindering the enzymatic hydrolysis of κ-casein, in particular that of the glycosylated forms.