ETHANOL-PRODUCTION FROM NONSTERILIZED CAROB POD EXTRACT BY FREE AND IMMOBILIZED SACCHAROMYCES-CEREVISIAE CELLS USING FED-BATCH CULTURE

The production of ethanol from carob pod extract by free and immobiliz ed Saccharomyces cerevisiae cells in batch and fed-batch culture was i nvestigated. Fed-batch culture proved to be a better fermentation syst em for the production of ethanol than batch culture. In fed-batch cult ure, both free and immobilized S. cerevisiae cells gave the same maxim um concentration (62 g/L) of final ethanol at an initial sugar concent ration of 300 g/L and F = 167 mL/h. The maximum ethanol productivity ( 4.4 g/L h) was obtained with both free and immobilized cells at a subs trate concentration of 300 g/L and F = 334 mL/h. In repeated fed-batch culture, immobilized S. cerevisiae cells gave a higher overall ethano l concentration compared with the free cells. The immobilized S. cerev isiae cells in Ca-alginate beads retained their ability to produce eth anol for 10 days. (C) 1994 John Wiley & Sons, Inc.