A kinetic study of the alcoholic fermentation of grape juice

Abstract

Abstract The alcoholic fermentation of grape juice by a wine yeast was studied batchwise at pH 3.6 and 4.05 to develop kinetic equations relating cell concentration, N , to product concentration, P . In the exponential growth phase where A , B , and C are constants, and μ is the specific growth rate. In the stationary phase, where the cell population is constant, was found to apply. This equation, which incorporates a stoichiometric constant, P m , predicted correctly the operation of a continuous fermentor at pH 3.6 and at 4.05. To study more fully the effect of alcohol concentration on yeast growth, a continuous fermentor was used in which the grape juice feed was supplemented with pure alcohol. At pH 3.6 the specific growth rate varied as, There was no growth inhibition below an alcohol concentration of 2.6 g./100 cc., but inhibition was complete above 6.85 g./100 cc. This is a modified form of the relation suggested by Hinshelwood. 1 The data suggest that growth in batch culture was limited not only by alcohol but also by some other factor, probably a nutritional deficiency.