Thermal and high-pressure inactivation of tomato polygalacturonase: A kinetic study

Abstract

Polygalacturonase (PG) was extracted from tomato fruit. The inactivation kinetics of the PG crude extract was investigated under isothermal and isobaric-isothermal conditions. Thermal inactivation of tomato PG in the temperature range 58 to 65°C could be described by a fractional conversion model, and in the temperature range from 70 to 90°C by a biphasic model. Pressure-temperature inactivation (range 300 to 600 MPa/5 to 50°C) of tomato PG could be described by a fractional conversion model, which points to first-order inactivation kinetics of a pressure-sensitive enzyme fraction and to the occurrence of a pressure-stable PG fraction. A mathematical model describing the influence of pressure and temperature on the inactivation rate constant was formulated.