Treating Distillers’ Grain from the Luzhou Aroma/Flavor Industry To Degrade Fiber

Abstract

To minimize environmental contamination and waste of resources, distillers’ grain (DG) from the Chinese liquor industry was used to produce reducing sugars for Bacillus thuringiensis cultivation. Four different pretreatments, using sodium hydroxide (0.5–2% w/v, 50–121 °C, 1 h), calcium hydroxide (0.2–4% w/v, 50–121 °C, 1 h), dilute sulfuric acid (0.5–2% w/v, 50–121 °C, 1 h), and hot water (50–121 °C, 1 h), were investigated in order to determine the optimal method for degrading cellulose in DG to produce monomeric sugars. Enzymatic hydrolysis and fermentation followed each pretreatment method. The results showed that the highest yield of monomeric sugars was obtained by using 2% dilute sulfuric acid treatment at 121 °C for 1 h (giving 313 g/kg DG), which was significantly higher (p < 0.001) than the yields obtained using other pretreatment methods. The highest spore count was achieved using this pretreatment with the addition of supplements. The utilization of DG in this study provides a plentiful carbon ...