Standardization of sugar beet juice extraction by microwave heating and its fermentation for bioethanol production

Abstract

Sugar beet juice was used as a substrate for bioethanol production owing to its high sucrose content as an alternative to first generation sucrose resources such as molasses, sugar cane juice etc. The juice of sugar beet, variety SZ-35, was extracted by microwave pre-heating treatment of succulents for 10 minutes giving total soluble solids (12.8 ± 0.74 ˚B). Two yeast strains, Saccharomyces cerevisiae KY069279 (isolated strain) and Saccharomyces cerevisiae D7 (commercial strain), were studied for their growth profile on sugar beet juice which revealed Saccharomyces cerevisiae KY069279 to have maximum growth rate (0.45 per hour) at 12 hours of shaking conditions. The selected yeast strain Saccharomyces cerevisiae KY069279 was further employed for the optimization of fermentation parameters (brix, inoculum size (%v/v) and DAHP supplementation (mg/100ml)) using RSM plan of Design Expert 10.0 software. The results were recorded in three responses viz. brix, reducing sugars and ethanol revealed 14.5˚B with inoculum size of 6%v/v, supplemented with 1mg/ml of DAHP was found to produce maximum ethanol (8.61%v/v) after 92 hours of fermentation at 25˚C with a fermentation efficiency of 92.7%.