Isolation of Wine Yeast from Sugar Rich Sources

A total of 21 yeasts was isolated from different sugar rich sources (date palm, pomegranate, roselle, orange, grapes and dry date palm juice) collected from different locations in West Bengal, India. All isolated yeasts were identified and differentiated based on their colony morphology and growth pattern in Yeast Extract- Peptone -Dextrose (YEPD) Agar medium. The isolates could continue to survive on the slants for up to a maximum of 6 months at 8-10°C temperature without any contamination. However, these were maintained by transferring to YEPD agar slants every four months to maintain the purity and maximum viability of cultures. Fermentation was carried out at 26±1°C temperature at total soluble solid 24oBrix and pH 4.70 in molasses medium for all different isolated yeast. The total soluble solid at the end of fermentation in molasses solution was found in the range of 9.00-20.78oBrix in all isolated yeast. The pH of the substrate was decreased (0.10-1.12) during fermentation. The cell count after complete fermentation was found in the range of 3.60×108 cfu/ml to 8.79×108 cfu/ml for all the isolated yeast. The concentration of alcohol in the molasses was observed a range from 4.21 to 13.61%. After screening or checking out the efficiency of yeasts on the basis of the highest alcohol production in molasses media, five yeasts (Y4, Y101, Y33, Y102, and Y7) were selected for wine fermentation out of 24 (new isolates 21, previous isolations Y4, Y7 and Y33) at the end of 18 days fermentation.