High-pressure processing of orange juice: Kinetics of pectinmethylesteraseinactivation

A kinetic study of pectinmethylesterase (PME) inactivation in orange juice was conducted. Juice samples were subjected to combinations of high pressur e (400, 500, 600 MPa) and thermal (25, 37.5, 50 degreesC) treatments for va rious time periods. PME inactivation followed a first-order kinetic model w ith a residual activity of pressure-resistant enzyme remaining. Calculated D-values ranged from 4.6 min to 117.5 min at 600 MPa/50 degreesC and 400 MP a/25 degreesC, respectively. Pressures in excess of 500 MPa resulted in suf ficiently fast inactivation rates for economic viability of the process.