Bioethanol production from fresh onion residues by yeast

Egypt is one of the largest countries of onion production; thus, possibility of ethanol production from onion residues by fermentation process was investigated. Onion residues of some Egyptian cultivars, including Giza 6, Giza 20, Giza red and Shandaweel1, were used for ethanol production by Saccharomyces cerevisiae as a biocatylast under different parameters, such as temperature, pH and using Botrytis cinerea as biodegrading bioagent. The results showed that the total sugars content of plants juice was 43.14 for Giza 6, 36.0 for Giza 20, 41.5 for Giza red, and 32.1 g/L for Shandaweel1. The optimal fermentation conditions for ethanol production from onions juice were found to be 6.0 for pH and 30 °C for temperature. Under these conditions highest ethanol production rate of 86% (6.4 g\L\hour) was obtained from Giza 6 cultivar residues treated with B. cinerea.. Based on these results, onion residues which is an agricultural waste is a promising alternative source for bioethanol production by S. cerevisiae.