Myrosinase, an enzyme found in all glucosinolate containing plants, is responsible for the conversion of glucosinolates into products that can be beneficial to Our health. In this study, the temperature and pressure stability of partially purified myrosinase from mustard seeds was studied in a model system. Temperature inactivation started at 60 degrees C and the inactivation kinetics were studied in detail between 65 and 75 degrees C. Inactivation could be described by the Consecutive step or the biphasic model. Mustard seed myrosinase was quite pressure stable, as its activity was retained after pressure treatments up to 600 MPa combined with temperatures up to 60 degrees C. At low pressures there was an antagonistic effect between pressure and thermal treatment, since myrosinase activity was retained after treatments at 70 degrees C up to 300 MPa. This pressure stability indicates that pressure treatment may be a valuable alternative for thermal treatment if one wants to retain myrosinase activity. (c) 2005 Elsevier Ltd. All rights reserved.