PRESSURE-INDUCED INACTIVATION OF SELECTED FOOD ENZYMES

Pectinesterase, lipase, polyphenol oxidase, lipoxygenase, peroxidase, lactoperoxidase, phosphatase and catalase have been examined at distin ct conditions within a pressure range of 0.1 to 900 MPa, temperatures from 25 degrees C to 60 degrees C, pH 3 to 7, and time of treatment of 2 min to 45 min. Results in model buffers made it possible to rank th r enzymes according to their pressure induced inactivation in the foll owing order: lipoxygenase, lactoperoxidase, pectinesterase, lipase, ph osphatase, catalase, polyphenol oxidase, peroxidase. A combination of pressure with moderate temperature increased the degree of enzyme inac tivation. Pressure treatment of real food systems showed a protective effect of food ingredients on the pressure inactivation of most enzyme s evaluated. For example sucrose protected pectinesterase from inactiv ation by pressure while lactoperoxidase and lipoxigenase were as stabl e in milk as in buffer.