Thermal inactivation of pectin methylesterase from different potato cultivars (Solanum tuberosum L.)

Abstract

Pectin methylesterase (PME) is an important enzyme that can alter the texture of potato products during processing and storage. To manage the textural properties of potato based products, low and/or high temperature blanching can be used to promote or inactivate PME, respectively. However, the many potato cultivars being used for processing may contain PMEs with a different thermal stability. Therefore, the thermal inactivation of PME extract from three different potato cultivars (Fontane, Royal and Innovator) was studied. A thermostable and thermolabile enzyme fraction were found in all three cultivars, being inactivated at temperatures from 45 °C and 57.5 °C on, respectively. Innovator may contain a lower level of thermostable PME than the other cultivars tested. The inactivation rate constant of the thermostable PME fraction was lower than the rate constant of the labile fraction at a reference temperature of 55 °C, but no significant differences between the respective rate constants of the different cultivars were found. The thermal inactivation kinetics of PME extract from Fontane were investigated in detail and represented by a first order model that allows the calculation of temperature-time combinations to reach a target residual PME activity.