Kinetics of tomato pectin methylesterase inactivation by temperature and high pressure

In this study we investigated the inactivation of endogenous pectin methylesterase (PME) in tomato juice during combined high-hydrostatic pressure (ambient to 800 MPa) and moderate temperature (60 to 75degreesC) treatments under Isobaric and Isothermal processing conditions. PME Inactivation rates increased with Increasing processing temperature, with the highest rate obtained during processing at 75degreesC and ambient pressure. Inactivation rates were dramatically reduced as soon as processing pressure was raised. High inactivation rates were again attained when processing pressure exceeded a value of about 700 MPa. Such a behavior was described by considering two parallel mechanisms of inactivation, each one following first order kinetics with Its own kinetic parameters.