Study On The Technology Of Producing Fuel Alcohol From Litch Residues

Litch has a high yields in china, Lychee processing products sold well at home and abroad. Litch residue is a side product of Lychee processing industry. Litch residue contains a lot of sugar, in which microbial can growth well. Develop litchi residue resources can avoid environmental pollution as well as making full use of biological resources. In this study, litch residue was used to produce fuel alcohol. This study involved in component analysis and litch residue pretreatment, strain screening, fermentation conditions optimization, kinetic model of alcohol production from litch residue.The nutritional components of litch residue was analyzed in this paper, results show that the water content was 83.18 %, crude fiber content was 0.46 %, total sugar content was 2.67 %, reducing sugar content was 2.53%, protein content was 0.64 %, fat content was 0.02 %, pectin content was 2.00 %. Meanwhile, in order to improve the amounts of glucose in the hydrolysates of litchi residue, Saccharification process was optimized. The result of single factor test and orthogonal test show that the best hydrolysates conditions were as follow: pH was 5.0, hydrolysates temperature was 50℃, hydrolysates time was 1.5h and enzyme concentration was 65 U/g.The fermentation characters of 5 yeast strains were compared. The result indicated that angel super yeast had a great comprehensive fermentation characters on litch residue. In this paper, we used angel super yeast as our fermentation strain, the influence of different fermentation conditions on the yield of alcohol were studied. Based on the result of the single factor test, the fermentation time and fermentation temperature as well as pH were chosen as influence factors. Response surface methodology was used to optimize the fermentation conditions of litch residue. The optimum conditions were as follow: fermentation time was 55 h, fermentation temperature was 35℃, pH was 4.75.In order to predicate the variation of alcohol yield during the fermentation, the kinetics of angel super yeast ferment litch residue was studied in this paper. The change of it parameters was determined, the model of yeast cell growth and alcohol production as well as glucose consumption during litch residue fermented by angel super yeast were set up.