Abstract

The alcoholic fermentative ability of yeast strains; Saccharomyces cerevisiae (isolated from yam), S. cerevisiae (from sugarcane molasses), S. carlsbergensis (from sugarcane molasses) and S. cerevisiae var. ellipsoideus (from orange juice) were examined on orange juice (Citrus sinensis). The quality of the wine produced on the basis of the acidity, ash content, vitamin C and the alcohol content were assayed. The fermentation efficiency varied between 48.05% with S. cerevisiae var. ellipsoideusand 99.46% with S. carlsbergensis. The highest ethanol concentration, yield and productivity were 6.80 ± 0.07% (w/v), 0.46 gg^-1 and 0.57g l^-1h^-1, respectively. The rate of sugar utilization was least, (2.76 g/day) with S. carlsbergensis and highest (3.07 g/day) with S. cerevisiae from yam. The total alcohol produced was least (3.19 ±0.21%, w/v) with S. cerevisiae var. ellipsoideus and highest (6.80 ± 0.07%, w/v) withS. carlsbergensis. The optimum pH ranged between 3.81 for S. cerevisiae var. ellipsoideus and 3.71 for S. cerevisiae (from yam). The Vitamin C level was highest (9.02 mg/100 g) with S. cerevisiae var. ellipsoideus and lowest (6.65 mg/100 g) withS. carlsbergensis.

Key words: Saccharomyces, yeast strains, fermentation, orange wine.