THE EFFECT OF PITCHING YEAST AERATION ON THE PRODUCTION OF ACETIC-ACID DURING FERMENTATIONS WITH BREWERS-YEAST - AN ENZYMATIC APPROACH

Aeration of pitching yeast signicantly increases the metabolism of acetate. This increase is particularly noticed at an enzymatic level, with special reference to the specific activity of the Fe+++ linked pyruvate de‐carboxylase which has been shown to be involved in the production of acetic acid. At the beginning of fermentations carried out with aerobic and anaerobic pitching yeasts, an increase in acetic acid production is observed, this is followed by reabsorption. Stabilisation in the concentration of acetic acid is observed until the end of fermentation. Initial and final concentrations of acetic acid obtained during fermentations were significantly higher in fermentations carried out with aerobic pitching yeasts than in fermentations carried out with anaerobic pitching yeasts. 1990 The Institute of Brewing & Distilling