酸-超声波预处理及糖化水解稻草研究

采用室内实验方法，研究了酸-超声联合预处理稻草对其化学组成以及糖化效果的影响，并与传统酸预处理法的效果进行了对比。结果表明，与未经处理的稻草相比，经酸-超声波处理的稻草其半纤维素、木质素含量最高分别减少了64．46％、62．19％，纤维素含量最高则上升了73．20％，而酸处理的稻草相应数值只能达到56．72％、59．90％及53．41％。同时分别对两种方法的稻草糖化的工艺条件通过正交试验进行了优化，得出两种方法的稻草最佳糖化条件均为：pH值为4．8，温度为45℃，酶浓度为20mg·g-1。在该条件下，对于酸一超声波预处理稻草，在糖化108h以后还原糖浓度稳定并达到最大值26．4g·L-1，而对于酸预处理稻草，在糖化120h以后还原糖浓度才稳定并达到最大值26．2g·L-1，且前者能比后者产生更多的葡萄糖以及更少的木糖，更有利于提高后续酒精发酵的效率。

Study on Ultrasound-assisted Acid Pretreatment of Rice Straw and Its Enzymatic Hydrolysis

The effect of combination pretreatment with ultrasound and acid to the chemical composition of rice straw and its enzymatic hy- drolysis were investigated. Meanwhile it was compared with the acid-alone pretreated process. The results showed that in contrast to the unpretreated rice straw, both the content of hemicelluloses and lignin in the pretreated rice straw decreased at a maximum of 64.46% and 62.19% with the ultrasound-assisted acid respectively, and the content of cellulose increased at a maximum of 73.20%, while the rice straw pretreated by acid only were 56.72%（hemicelluloses ）, 59.90%（ lignin ）and 53.41%（cellulose ）respectively. The enzymatic hydrolysis condi- tions of these two pretreatments were optimized by an orthogonal test. Both methods of the optimal enzymatic hydrolysis conditions were the same：pH 4.8, temperature 45 ℃ and enzyme loading 20 mg·g-1 substrate. Finally, it was indicated by the results that rice straw pretreated by ultrasound-assisted had the highest concentration of reducing sugar by 26.4 g·L-1 after an 108 h enzymatic hydrolysis, and the rice straw pretreated by acid only had 26.2 g·L-1 after an 120 h enzymatic hydrolysis. The rice straw was pretreated by ultrasound-assisted had a higher hydrolysis rate and produced a hydrolysate with higher glucose content and lower xylose content which was more suitable for subsequent fermentation in comparison with the one by acid alone.