Kinetic study of the irreversible thermal and pressure inactivation of myrosinase from broccoli (Brassica oleracea L. Cv. italica)

J Agric Food Chem. 1999 May;47(5):1794-800. doi: 10.1021/jf980964y.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brassica / enzymology*
  • Enzyme Stability
  • Glycoside Hydrolases / antagonists & inhibitors
  • Glycoside Hydrolases / chemistry*
  • Hot Temperature
  • Kinetics
  • Pressure
  • Thermodynamics

Substances

  • Glycoside Hydrolases
  • thioglucosidase