Method for on-line prediction of kinetics of alcoholic fermentation in wine making

Abstract

The rate of alcoholic fermentation in wine making has been determined in real time from the measurement of the volume of CO 2 released. It includes three successive phases characterized by four kinetic parameters: the time of onset of gas release ( Td), the acceleration of CO 2 production ( k 1), the maximal rate of CO 2 production ( V max), and the slope of the logarithm of the rate of CO 2 release during the deceleration phase ( k 2). A model of these four parameters considering only the process temperature and the initial sugar concentration was insufficient, since mean errors were between ±20 and ±50%. Satisfying results were obtained in real time application, modeling V max and k 2 on the basis of accelerated CO 2 production ( k 1) calculated 5 h after the onset of gas production ( Td + 5). The precision of the polynomial models obtained were ±5.8% for V max and ±10.4% for k 2. Their application led to an early prediction of the course of the alcoholic fermentation process in isothermal conditions.