响应面试验优化蒸汽爆破酸解制备玉米皮渣还原糖工艺及水解程度分析

Preparation of Reducing Sugar from Corn Bran by Steam Explosion Combined with Acid Hydrolysis: Process Optimization Using Response Surface Methodology and Analysis of Hydrolysis Degree

为提高湿法加工玉米淀粉产生的副产物玉米皮渣中还原糖的得率,以玉米皮渣为原料,研究蒸汽爆破处理原料、酸水解法制备还原糖的最优工艺条件,对硫酸体积分数、水解时间、水解温度和料液比4个因素分别进行单因素试验,根据单因素试验结果设计Box-Behnken试验,以还原糖含量为指标值,采用响应面分析法确定降解的最优工艺参数,通过离子色谱法分析水解产物的组分。结果表明:最优工艺参数为硫酸体积分数1.66%、水解时间1.5 h、水解温度120℃、料液比1∶10(g/m L),此条件下还原糖含量为54.61%,比未经蒸汽爆破处理的降解液中还原糖含量高出9.58%。降解液经离子色谱分析后发现主要含3种还原糖,分别为D-葡萄糖19.34?mg/m L、D-木糖16.01?mg/m L、L-阿拉伯糖10.37?mg/m L。同时对降解剩余物进行分析后发现,与原料相比蒸汽爆破酸解剩余物的纤维结构较疏松,裂解程度大,表面有孔洞和裂痕,说明蒸汽爆破酸解处理对纤维素、半纤维素及木质素的溶解力较强。这与两者降解液中还原糖含量结果相一致。

In order to increase reducing sugar yield from corn bran as a by-product of the production of corn starch bywet milling, the optimal conditions for preparation of reducing sugar from corn bran by steam explosion combined withacid hydrolysis were investigated in this research. First of all, the one-factor-at-a-time method was employed to examinethe effects of sulphuric acid concentration, hydrolysis time, temperature and material-to-liquid ratio on reducing sugarcontent. Subsequently, the optimization of process parameters for improved reducing sugar content was performed usingBox-Behnken design and response surface methodology. Hydrolysates were analyzed by ion chromatography. The resultsshowed that the maximum reducing sugar content of 54.61% was obtained under the following optimal conditions： sulphuricacid concentration, 1.66%; hydrolysis time, 1.5 h; temperature, 120 ℃; and material-to-liquid ratio, 1：10 （g/mL）, whichwas increased by 9.58% as compared to that obtained without steam explosion pretreatment. Ion chromatography analysisindicated that the hydrolysate obtained was mainly composed of D-glucose （19.34 mg/mL）, D-xylose （16.01 mg/mL）and L-arabinose （10.37 mg/mL）. In comparison to the raw material, the fiber structure of the residue left after the preparation ofreducing sugar was more loose and more significantly cracked, showing more holes and cracks on its surface, revealing that thecellulose, hemicellulose and lignin in corn bran can be well decomposed by successive steam explosion and acid hydrolysis. Thisresult is in accordance with the reducing sugar content in the degradation solution obtained after both treatments.