Rheological properties of rennet-induced milk gels as affected by high pressure treatment at different temperatures

The effects of high pressure treatments (483 MPa and 676 MPa) at different temperatures (10, 30 and 40°C) on the rheological properties of coagulant-induced milk gels were investigated by dynamic viscoelasticity measurements. Gels prepared from pressurized milk (483 MPa) at 10°C had higher G′ and gel firmness values, while pressurization at 40°C resulted in lower values compared to the untreated milk gel. Treatments of 483 MPa at 40°C and 676 MPa at 30 and 40°C caused dramatic decreases in the values of G′ and gel strength. The combined effects of pressure treatment and high temperatures caused a progressive increase in milk turbidity without changing pH values. While a pressure-treatment of 483 MPa at 10°C may promote firm gel formation, pressure-temperature treatments of milk at or exceeding 483 MPa at 40°C or 676 MPa at 30°C may impair gel-forming properties of the milk and lead to weak gels.