KINETIC OF SUGAR CONSUMPTION AND ETHANOL PRODUCTION ON VERY HIGH GRAVITY FERMENTATION FROM SYRUP OF DATES BY- PRODUCTS (Phoenix dactylifera L.) BY USING Saccharomyces cerevisiae, Candida pelliculosa AND Zygosaccharomyces rouxii
Three yeasts, Saccharomyces cerevisiae, Zygosaccharomyces rouxii and Candida pelliculosa, were tested for ethanol production on dates’syrup. In batch fermentation, the ethanol concentration depended on the initial sugar concentration and the yeast strain. For an initial sugar concentration of 17.4°Brix, maximum ethanol concentration was 63 g/L during S. cerevisiae growth, higher than the amounts achieved during Z. rouxii and C. pelliculosa growth, 33 g/L and 41 g/L respectively. On 35.8°Brix initial sugar amount, only Z. rouxii was able to grow, resulting in 50 g/L ethanol production, showing an inhibitory effect on S.cerevisae and C. Pelliculosa due to the osmotic stress resulting from the high sugar concentration.