Thermal and high hydrostatic pressure inactivation of myrosinase from green cabbage: A kinetic study

Myrosinase, a family of enzymes which coexist with glucosinolates in all Brassica vegetables, catalyses the hydrolysis of glucosinolates to yield compounds that can have beneficial effects on human health. In this study, the thermal and pressure inactivation of myrosinase from green cabbage was kinetically investigated. Thermal inactivation started at 35 degrees C and inactivation kinetics was studied in the temperature range 35-55 degrees C. Thermal inactivation of green cabbage myrosinase followed the well known consecutive step model. Pressure inactivation started at 300 MPa, even at 10 degrees C, and the consecutive step model effectively described pressure inactivation in the range 300-450 MPa at 10 degrees C. The combined effects of applying various pressures and temperatures on myrosinase inactivation kinetics were studied in the ranges 35-50 degrees C and, 100-400 MPa. The inactivation followed first-order kinetics at all of the applied combinations. This study demonstrates that myrosinase from green cabbage is highly susceptible to both thermal and high pressure processing. Furthermore, it is also noted that myrosinase stability during processing appears to vary widely between different Brassica species. (C) 2011 Elsevier Ltd. All rights reserved.