Inoculum Size and Age Studies on Single and Mixed Strain Fermentation of Grape Juice

Single and mixed strain fermentation were compared to check the effect on properties of wine. Two strains of Saccharomyces cerevisiae (MTCC 11815 & MTCC 170) were used to study the effect of inoculum age and inoculum size on fermentation of grape juice. The inoculum sizes used were 2%, 5%, 10% and 15%, while inoculum age effect was studied using 24 h, 48 h and 60 h old inoculum. Fermentation efficiency of 77.2% was achieved in mixed strain culture using 15% inoculum, 17% initial sugars giving ethanol concentration of 6.70% (w/v) after 48 hrs. Fermentation efficiency of 84.65% was achieved with MTCC170 using 15% inoculum and 17% initial sugars giving ethanol concentration of 7.34% (w/v) in 48 hrs. Strain MTCC11815 produced 8.5% (w/v) ethanol from 17% initial sugars giving 98% efficiency using 2 and 5% inoculum. Concentration of phenolics increased with inoculum concentration while nitrogen and phosphates did not show any regular trend. The nitrogen and phosphate concentration was affected by type of strain rather than other factors.