SUGAR UPTAKE AND SUBSEQUENT ESTER AND HIGHER ALCOHOL PRODUCTION BY SACCHAROMYCES-CEREVISIAE

The production of a number of esters and higher alcohols by brewing st rains of Saccharomyces cerevisiae, in synthetic media containing only glucose, fructose or maltose as sole carbohydrate source, has been inv estigated. Results indicated that production of most volatiles was gen erally lower when maltose was the sugar being fermented, despite malto se-grown cells having higher viabilities and vitalities than glucose o r fructose-grown cells. There was no significant difference in the lev els of esters and higher alcohols produced during fermentation when gl ucose or fructose was metabolised, although strain variation was obser ved. Similar results were obtained when wort was supplemented with eit her glucose, fructose or maltose. Wort supplemented with maltose produ ced fewer volatiles, especially higher alcohols, than that which had a hexose sugar added. The activity of ester-synthesising enzymes presen t in glucose or maltose PYN grown cells was also examined. Similar lev els of ethyl acetate and isoamyl acetate were obtained when cells grow n in either glucose or maltose PYN were disrupted and ester production monitored. The implications of these results for the fermentation of high-gravity worts are discussed.