Effect of temperature and nitrogen supplementation on bioethanol production from waste bread, watermelon and muskmelon by Saccharomyces cerevisiae

This study was undertaken to investigate the effect of temperature (25 degrees C and 30 degrees C) and nitrogen supplementation (with 20 g/L peptone or without) on bioethanol production from waste bread, watermelon and muskmelon feedstocks by Saccharomyces cerevisiae. Nitrogen addition resulted in higher ethanol yields at both temperatures. Fermentation at 30 degrees C produced a higher ethanol yield than at 25 degrees C. The highest ethanol yield of 0.502 gethanol /g fermentable sugar, at 98.22% of the theoretical maximum, was obtained from the fermentation of muskmelon juice at 30 degrees C with nitrogen supplementation. Ethanol yields at both temperatures were significantly different (p < 0.05) between the trials with nitrogen and without nitrogen supplementation for watermelon and muskmelon but not for waste bread hydrolysate. On the other hand, ethanol yields showed significant differences (p < 0.05) at 25 degrees C and 30 degrees C for all feedstocks with nitrogen and without supplementation.