Comparative effects of high isostatic pressure and thermal processing on the inactivation of rhizomucor miehei protease

Abstract

This study compared the inactivation of the proteolytic (PA) and milk-clotting (MCA) activities of Rhizomucor miehei protease by high isostatic pressure (HIP) up to 600 MPa/20 min/25 °C and by a thermal process (TP) up to 72.0°C/30 min. Pressures above 300 MPa caused a loss of enzyme activity, MCA being expressively more affected than PA. The inactivation of the protease showed a nonlinear behavior, converging to a two-component system model (stable and labile fractions). The stable fraction represents higher activity for PA and the labile for MCA. The D-values for stable PA (3.35 ± 0.42 min for HIP and 5.58 ± 0.48 min for TP) and labile MCA (0.34 ± 0.04 min for HIP and 0.47 ± 0.04 min for TP) were significantly lower for the HIP processed enzyme, highlighting the effectiveness of the process in inactivating this enzyme. Therefore, the results highlight HIP at 600 MPa as an optional process to inactivate R. miehei protease (without the use of heat), being more effective than the thermal process