Abstract

The influence of two inocula levels of the yeast Saccharomyces bayanus, BV 818, 0.01 (w/v) and 0.02% (w/v) on physico-chemical properties of fermented tomato juice was investigated. The properties studied include alcoholic strength, dry extract, residual sugar, pH, titratable acidity and volatile acidity. During fermentation, the pH, titratable acidity, brix, CO₂ production and changes in phenolic composition of the fermented juice were monitored. Both pH and titratable acidity showed an upward trend for the fermented juices. Alcoholic strength of the fermented juice produced with 0.01% (w/v) inoculum level was significantly higher (p<0.05) than that produced with 0.02% (w/v). The total phenolics and pH for wine obtained from 0.02% (w/v) inoculum level were significantly higher (p<0.05) than that from 0.01%. Volatile acidity values of both wines were below the permitted levels. During ageing, most colour parameters showed higher values in both fermented juices. Inoculum level 0.01% (w/v) gave better physico-chemical qualities and was therefore found to be better than 0.02% (w/v) in producing fermented tomato juice. The 0.01% (w/v) inoculum-fermented tomato juice scored higher for overall acceptance than that of 0.02% (w/v) inoculum-fermented tomato juice, but the acceptance levels were not significant.

Key words: Tomato, inoculum level, wine, fermentation.