Preparation of very high gravity cassava mashes and subsequent fermentation to ethanol using Saccharomyces bayanus

Abstract

Fuel ethanol was produced from very high gravity (VHG) cassava mashes (30-40% w/v dry matter content) using flocculating yeast Saccharomyces bayanus. The total reducing sugars (TRS) concentrations of 30%, 35% and 40% mashes after starch liquefaction and saccharification were 29.0%, 31.64% and 37.15% (w/v), respectively. After 72 h fermentation, final ethanol concentrations reached 101.8 and 94.6 g/L with fermentation efficiencies of 75.8% and 57.8% in 30% and 35% mashes, respectively. A complete inhibition of yeast growth and fermentation was observed in the mash containing 40% dissolved solids.