THE KINETICS OF PECTIN METHYL ESTERASE IN POTATOES AND CARROTS DURINGBLANCHING

The activity of pectin methyl esterase (PE) in potatoes and carrots du ring blanching treatments was modelled and analysed. Two iso-enzymes w ere found to exist, one bound and one soluble. The bound form can be c onverted into the soluble form. These iso-enzymes have a different sus ceptibility to conversion and heat denaturation. All rate constants of reaction were modelled as dependent on temperature according to Arrhe nius' law. Regardless of the daily variance in measuring the series th e variance accounted for by the model in multivariate nonlinear regres sion analysis was more than 90% for both the individual activity data and the mean data. The same model formulation could be applied for act ivities assayed against pectin of 8% and of 68% esterification. The pa rameter values obtained were highly comparable in both analyses. (C) 1 998 Elsevier Science Limited. All rights reserved.