Abstract

Fresh palm wine samples were obtained from oil palm and raffia palm into sterile flasks. The samples were examined for yeasts properties and performance in wine making using grapes. The yeasts in the palm wine were characterized, identified, and screened for their sedimentation rate, ethanol tolerance, alcohol content, yeasts population, pH, total acidity (TA), total soluble solids, reducing sugar and total sugar at 6 h intervals. The yeasts from the samples were purified and used to inoculate grape must. Variation in temperature, alcohol contents, pH, specific gravity, total solids, titratable acidity and volatile acidity were determined. There were significant differences (P<0.05) between the yeast properties in oil palm and raffia palm.Saccharomyces cerevisiae, Saccharomyces globosus and Saccharomyces carlsbergensis were isolated from the palm wine samples. Ethanol tolerance was between 15 and 18% v/v in oil palm and 12 to 15% v/v in raffia palm after 24 h. Yeast population increased (10⁸ to 10⁹ cfu/ml) with increased level of ethanol and TA with corresponding reduction in pH level (6.7 to 4.6). Yeast performance in grape wine indicated significant differences (p<0.05) between oil palm and raffia palm samples. TA and ethanol production (9 to 11.4%) were lower as compared to that in the palm wine. The pH was fairly stable. This study indicates that palm wine yeasts have good properties for wine production from fruits.

Key words: Ethanol tolerance, grape wine, palm wine yeasts, Saccharomyces,yeasts properties.