Abstract:
Factors affecting the secondary fermentation of sparkling mulberry wine were studied i.e. yeast strain, sugar concentration, di-ammonium hydrogen phosphate (DAP) concentration and yeast concentration . The mulberry base wine contained alcohol 11.2% v/v, total acid 0.77%w/v, reducing sugar 42 mg/100ml, total soluble solid 5.40Brix and pH 3.3. Three yeast strains i.e. Saccharomyces bayanus Lalvin EC-1118, Saccharomyces cerevisiaeMaurivin PMD and Saccharomyces cerevisiae Maurivin AWRI 796 were evaluated for the production CO2 in the secondary fermentation. The volume of CO2 was measured every 4 hours until no gas production using CO2 gasometric apparatus modified from Chittick apparatus (A.O.A.C.25.1.02, 1995). The gas weight was calculated using ideal gas equation (PV=nRT). The results indicated that EC-1118 yeast was the best CO2 producer (0.890g) which was not significantly different (p˃0.05) from PMD yeast (0.888g), but statistically significant difference (p≤0.05) from AWRI 796 (0.713g). CO2 producing efficiency of EC-1118 and PMD were 0.045 and 0.043 g/109 cells/day respectively. Secondary fermentation parameters i.e. sugar concentration (1.3 and 2.5%), DAP concentration (100, 300 and 500 ppm), and yeast concentration (50 and 100 ppm) were studied. Only the sugar concentration was statistically significant related with pressure in the bottle and time of yeast fermentation. At 15℃ and the addition of 1.3% sugar, the final pressure of gas CO2 was 3.5 atm pressure in the bottle and the fermentation was completed in 3 weeks. While at 2.5% sugar concentration, the final pressure of gas CO2 was 6.3 atm pressure in the bottle and the fermentation was completed in 5 weeks. Sensory evaluation of the sparkling wine (1.3 and 2.5% sugar concentration, 100 ppm DAP and 50 ppm yeast powder) performed by visual, nose and mouth showed that the wine from the addition of 2.5% sugar was better than the other. In conclusion, sparkling mulberry wine can be produced by using Saccharomyces bayanus Laivin EC-1118 at the concentration of yeast powder 50 ppm (3.1 x 106 cells/ml ) with the addition of sugar and DAP in the secondary fermentation at 2.5% and 100 ppm,respectively.