KINETICS OF POLYGALACTURONASE ACTIVITY AND FIRMNESS OF PEACHES DURINGSTORAGE

The activity of endo-polygacturonase (PG) in peaches during storage at different constant temperatures is shown to be the result of a format ion from some inactive predecessor and a denaturation or decay into an inactive form. This whole process strongly resembles the normally enc ountered turnover: On these premises, a process-oriented mathematical model is formulated The variance accounted for by rite model in multiv ariate nonlinear regression analysis is more than 80% for the data gat hered in two successive seasons. Analysis of the data from both season s combined did not elect-ease the descriptive power of the model, rega rdless the fact that the maturity at harvest and the initial level of enzyme activity showed major differences. The values of the parameters obtained from the data of both seasons combined were comparable with those of the individual seasons. The effect of the action of PG on the firmness of peaches was also modelled and analysed with an variance a ccounted for of almost 90%. The parameters obtained with respect to de naturation of the enzyme were highly comparable, (C) 1998 Elsevier Sci ence Limited. All rights reserved.