Abstract
The general trend in sorghum beer production is now the use of starter culture to alleviate the problems of variations in organoleptic quality and microbiological stability. In this study, we aimed to select strains of Saccharomyces cerevisiae and Candida tropicalis to use as starter culture based on their ability to face ethanol toxicity. All the strains exhibited a relatively high resistance up to 5% ethanol. At 7.5% ethanol, S. cerevisiae F12-7 and C. tropicalis C0-7 were the most resistant strains with viability rate of 80-97% after 24 h of incubation. These two strains showed also the highest unsaturated/saturated fatty acids ratios. Values increased from 68.86% to 80.30% and from 72.97 to 85.96% respectively for S. cerevisiae F12-7 and C. tropicalis C0-7 cultivated under 0% and 7.5% ethanol. The cellular neutral lipid composition differed markedly according to the yeast strains. With proportion of 36.73% for S. cerevisiae F12-7 and 78.75% for C. tropicalis C0-7, ergosterol was the most abundant neutral lipid founded in the strains membranes. In addition, phosphatidylethanolamine contents decreased with the increase of ethanol concentration in the culture medium on contrary to phosphatidylcholine contents. These two strains were so suggested as starter cultures for sorghum beer production.