SELECTION OF THERMOTOLERANT YEAST FOR ALCOHOL FERMENTATION OF RAW CASSAVA STARCH

POUNGPORN CHOTICKAJ

ABSTRACT: Alcoholic fermentative activity of isolated thermotolerant yeasts was examined at 40 ^oC using raw cassava starch as substrate and wheat bran koji as saccharifying agent. Thirty of the isolated yeasts were found to produce alcohol, but only one isolate (Number 4) was found to be the most effective in terms of the highest amount of CO₂ evolved and hight concentration of alcohol produced. The alcohol concentration reached 8.45 % (v/v) after 5 days, giving alcohol yield of 81.0 % and residual direct reducing sugar 1.9 % This yeast was then selected for alcoholic fermentation of raw cassava starch at 40 ^oC, using rice bran koji as saccharifying agent. It was found that under optimal condition, an alcohol concentration of 7.95 % (v/v) could be obtained after 5 days, the alcohol yield 76.2 % and residual direct reducing sugar 2.6 %.

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Department of Biology, Faculty of Science, Ramkhamhaeng University, Bangkok 24, Thailand

Received 15 December 1982