Effect of mild-heat and high-pressure processing on banana pectin methylesterase: a kinetic study.

Pectin methylesterase (PME) was extracted from bananas and purified by affinity chromatography. The thermal-high-pressure inactivation (at moderate temperature, 30-76 degrees C, in combination with high pressure, 0.1-900 MPa) of PME was investigated in a model system at pH 7.0. Under these conditions, the stable fraction was not inactivated and isobaric-isothermal inactivation followed a fractional-conversion model. At lower pressure (< or =300-400 MPa) and higher temperature (> or =64 degrees C), an antagonistic effect of pressure and heat was observed. Third-degree polynomial models (derived from the thermodynamic model) were successfully used to describe the heat-pressure dependence of the inactivation rate constants.