Thermal and High‐Pressure Inactivation of Tomato Polygalacturonase: A Kinetic Study

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.