Chemical Composition of Sweet Sorghum Juice and its Comparative Potential of Different Fermentation Processes for Enhanced Ethanol Production

Abstract

The chemical composition of stalk juice of genotypes RSSV 9 and CSH 22SS of sweet sorghum and production of ethanol by fermentation in shake flasks and laboratory fermenter were determined. Sucrose was found to be higher in RSSV 9 (152.20 g/l) as compared to CSH 22SS (106.56 g/l). The reducing sugars and free fructose in stalk juice ranged between 29.72–33.25 and 11.38–14.40 g/l, respectively, among two genotypes. CSH 22SS contained higher amounts of reducing sugars and free fructose than RSSV 9. Higher amount of total phenolics i.e. 178.81 mg (GAE/l) was also found in CSH 22SS. In shake flasks, significant rise in ethanol production of 26.19 g/l at 15 h and 43.42 g/l at 18 h from RSSV 9 and 31.25 g/l at 15 h from CSH 22SS was found while in laboratory fermenter, significant increase in ethanol production of 29.58 g/l at 12 h and 49.29 g/l at 15 h from RSSV 9 and 28.19 g/l at 12 h and 35.12 g/l at 15 h from CSH 22SS was achieved. It was concluded that the fermentation process was accomplished quickly, resulting in higher volumetric ethanol productivity in a laboratory fermenter as compared to shake flasks.