Enzymatic degradation of polysaccharides in Chinese vinegar residue to produce alcohol and xylose

Abstract

Vinegar residue is a key secondary waste in the brewing industry that is often disposed irresponsibly, due to its large quantity and lack of reasonably effective use, causing environmental pollution issues. NaOH was used to pretreat Chinese vinegar residue, and the reaction products were consumed by the enzyme complex and Saccharomyces cerevisiae 1300 during the stage of simultaneous saccharification and fermentation (SSF). The results show that the optimal pretreatment conditions for Chinese vinegar residue were solid-to-liquid ratio of 1 : 11‏, NaOH concentration of 2.2%, pretreatment temperature of 63 °C, pretreatment time of 80 min, and amount of 4.9 IU g^–1 xylanase. While these optimal conditions allowed more effective enzymatic degradation of the dried vinegar residue and resulted in the total sugar yield of 66.1%. Subsequently, dried vinegar residue and enzyme complex were added into the SSF process four times, and SSF reacted in a shaker at 120 r min^–1 and 37 °C for 120 h, the yields of ethanol and xylose were 31.4% and 18.5%, respectively. Therefore, the method of Chinese vinegar residue for alcohol and xylose production by SSF was proved.