title: Kinetic study of the irreversible thermal and pressure inactivation of myrosinase from broccoli (Brassica oleracea L. Cv. italica).
abstract: Thermal and pressure inactivation of myrosinase from broccoli was kinetically investigated. Thermal inactivation proceeded in the temperature range 30-60 degrees C. These results indicate that myrosinase is rather thermolabile, as compared to other food quality related enzymes such as polyphenol oxidase, lipoxygenase, pectinmethylesterase, and peroxidase. In addition, a consecutive step model was shown to be efficient in modeling the inactivation curves. Two possible inactivation mechanisms corresponding to the consecutive step model were postulated. Pressure inactivation at 20 degrees C occurred at pressures between 200 and 450 MPa. In addition to its thermal sensitivity, the enzyme likewise is rather pressure sensitive as compared to the above-mentioned food quality related enzymes. By analogy with thermal inactivation, a consecutive step model could adequately describe pressure inactivation curves. At 35 degrees C, pressure inactivation was studied in the range between 0. 1 and 450 MPa. Application of low pressure (<350 MPa) resulted in retardation of thermal inactivation, indicating an antagonistic or protective effect of low pressure.
authors.affiliation: Department of Food and Microbial Technology, Faculty of Agricultural and Applied Biological Sciences, Katholieke Universiteit Leuven, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Ludikhuyze
authors.forename: V
authors.initials: V
authors.lastname: Ooms
authors.forename: C
authors.initials: C
authors.lastname: Weemaes
authors.forename: M
authors.initials: M
authors.lastname: Hendrickx
mesh_terms: D001937:Brassica / Q000201:enzymology*; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D006358:Hot Temperature; D007700:Kinetics; D011312:Pressure; D013816:Thermodynamics
chemical_list: D006026:Glycoside Hydrolases; C022739:thioglucosidase