ABSTRACT

Optimization of hydrolysis conditions of lignocellulosic biomass is crucial to able to produce value-added products by fermentation. This study not only determines optimal dilute sulfuric acid (H₂SO₄) hydrolysis conditions of wheat bran (WB) and rye bran (RB) by using one-factor-at-a-time method and subsequently Box–Behnken design but also elucidates chemical composition of hydrolysates yielded under optimal hydrolysis conditions. Based on the results, optimal hydrolysis conditions of WB and RB were 121 and 130°C of temperature, 1/8 and 1/8 w/v of solid to liquid ratio, 2.66 and 1.58% v/v of dilute H₂SO₄ ratio, and 30 and 16 min of implementation time, respectively. Hydrolysates obtained from WB and RB at these conditions contained 72.7 (0.58 g sugar/g biomass) and 89.4 g/L (0.72 g sugar/g biomass) of reducing sugar concentration, respectively. Hydrolysis rates of WB and RB were 87.79 and 91.33%, respectively. Main reducing sugar in RB hydrolysate was glucose with 31.17 g/L (0.25 g glucose/g biomass) while glucose and xylose were the main monosaccharides with 20.90 (0.17 g glucose/g biomass) and 18.69 g/L (0.15 g xylose/g biomass) in WB hydrolysate, respectively. With acidic hydrolysis of WB and RB, inhibitors such as phenolics, 5-Hydroxymethylfurfural, 2-Furaldehyde (not for RB), acetic acid, and formic acid (not for WB) formed. Catalytic efficiency values of H₂SO₄ for WB and RB were 15.2 and 24.4 g /g, respectively, indicating that inhibitor concentration in WB hydrolysate was higher than that of RB. These results indicated that WB and RB have a high potential in production of value-added products by fermentation.

摘要

优化木质纤维素生物质的水解条件对于能够通过发酵生产增值产品至关重要。本研究不仅确定了麦麸 (WB) 和黑麦麸 (RB) 的最佳稀硫酸 (H ₂ SO ₄ ) 水解条件，采用一次单因素法和随后的 Box-Behnken 设计，还阐明了在最佳水解条件下产生的水解产物的化学成分。根据结果​​，WB和RB的最佳水解条件为温度121和130℃，固液比1/8和1/8 w/v，稀H ₂ SO _{4 2.66和1.58% v/v}比率，以及 30 和 16 分钟的实施时间，分别。在这些条件下从 WB 和 RB 获得的水解产物分别含有 72.7（0.58 g 糖/g 生物质）和 89.4 g/L（0.72 g 糖/g 生物质）的还原糖浓度。WB和RB的水解率分别为87.79和91.33%。RB水解物中的主要还原糖是葡萄糖，为31.17 g/L（0.25 g葡萄糖/g生物质），而葡萄糖和木糖是主要的单糖，分别为20.90（0.17 g葡萄糖/g生物质）和18.69 g/L（0.15 g木糖/g）生物质）分别在 WB 水解产物中。随着WB和RB的酸性水解，形成酚醛树脂、5-羟甲基糠醛、2-糠醛（不适用于RB）、乙酸和甲酸（不适用于WB）等抑制剂。_H2SO4的催化效率_值WB 和 RB 分别为 15.2 和 24.4 g /g，表明 WB 水解产物中的抑制剂浓度高于 RB。这些结果表明WB和RB在发酵生产增值产品方面具有很高的潜力。