STUDY OF THE PERFORMANCE OF FOUR STRAINS OF SACCHAROMYCES CEREVISIAE DURING ETHANOL PRODUCTION WITH CASHEW APPLE JUICE (ANACARDIUM OCCIDENTALE L.)

Cashew nut production is booming in Benin and picking apples are a valuable commodity with a high nutrient content. The main objective of this study is the valorization of cashew apples through the study of the performance of four strains of Saccharomyces cerevisiae during ethanol production from cashew apple juice. The alcoholic fermentation of cashew apple juice with an initial concentration of 157.5 g/L of reducing sugars and 1 g/L of yeast was conducted anaerobically at room temperature (30.8 ?C) at pH 3.85-4.25 for 96 hours in polyethylenic triplicate bioreactors. During fermentation, it has been tested the performance of strains such as Saccharomyces cerevisiae var. bayanus, Saccharomyces cerevisiaeSafale K-97, Saccharomyces cerevisiae Saflager W-34/70 and baker's yeast. After 48 hours of fermentation the maximum concentration of ethanol (104.3 g/L) is recorded with the yeast Saccharomyces cerevisiae var. bayanus with a residual sugar of 1.25 g/L. It is followed by Safale K-97, Saflager W-34/70 and baker's yeast, which have ethanol concentrations of 93.69; 73.95; 58.16 g/L respectively. In addition, the yeast Saccharomyces cerevisiae var. bayanus showed the highest efficiency (96.025 %), the highest productivity (1.604 g.L-1.h-1), the highest ethanol yield (0.491 g.g-1) and the highest rate substrate consumption (2.067 %.h-1). It appears from this study that the yeast Saccharomyces cerevisiae var. bayanus has the best bioconversion performance of fermentable sugars in ethanol. Therefore, it can be used as an effective strain in the perspective of intensive ethanol production.