Abstract: Reducing the consumption of cellulase was the key factor to overcome the economic problem in the refining process of lignocellulose. In this study, the enzymatic hydrolysis performance of long fibers and short fibers fractionated by steam explosion classification and the possibility of using steam explosion classification to reduce the consumption of cellulase were investigated. The results showed that the enzymatic hydrolysis difficulty of short fiber was significantly lower than that of long fiber. The enzymatic hydrolysis rate of cellulose in short fiber was 1.62 times that of long fiber after 48 h of enzymatic hydrolysis at the enzyme dosage of 20 FPU/g DM. Under the enzyme dosage of 5 FPU/g DM, the enzymatic hydrolysis rate of cellulose in short fiber was 58.23% after 36 h. Under the enzyme dosage of 20 FPU/g DM, the enzymatic hydrolysis rate of cellulose in long fiber was only 51.54% after 36 h. The consumption of cellulase was reduced by 75%. The difference in enzymatic hydrolysis difficulty was due to the fact that long fiber and short fiber came from different tissues of corn straw. Due to the difference in mechanical strength, the tearing effect generated by the steam explosion crushed the husk and core into diverse particle sizes. The variety of volumes and shapes provided the basis for classification. Short fibers were mainly composed of parenchyma cells from the core, while long fibers were mainly composed of fiber cells from the husk. The crystallinity of cellulose in short fiber was lower, so the enzymatic hydrolysis difficulty was lower than that of long fiber. In addition, during the enzymatic hydrolysis of short fiber, the release of bound water was more sufficient. The liquefaction time of short fiber was shorter than that of long fiber. This indicated that mass transfer efficiency was improved during the enzymatic hydrolysis of short fiber, which was conducive to reducing the negative effect of product inhibition on enzyme activity and improving the enzymatic hydrolysis efficiency. This study provided an effective method for improving the homogeneity of lignocellulosic materials. The steam explosion classification technology effectively changed the difficulty of enzymatic hydrolysis of corn straw and saved the cost of cellulase. This was of great significance to the exploitation of lignocellulosic resources.

Key words: steam explosion classification, corn straw, enzymolysis performance, cellulase consumption, mechanical strength, mass transfer efficiency

摘要： 降低酶解过程中纤维素酶用量是克服木质纤维素资源炼制过程经济关的关键因素。本研究探索了秸秆汽爆分级后长短纤维酶解性质的差异及其来源，以及利用汽爆分级降低用酶量的可能性。结果表明，分级后的短纤维酶解难度较长纤维显著降低，其酶解率在用酶量仅5 FPU/g DM的情况下即可超过长纤维在20 FPU/g DM时的酶解率，将用酶量降低75%，这主要是由于长短纤维的组织来源不同。由于力学强度的差别，汽爆后秸秆不同组织粒径各异，为分级提供了基础。短纤维主要由来自髓芯的薄壁细胞组成，纤维素结晶度较低，较长纤维具有更低的酶解难度。此外在短纤维酶解过程中束缚水释放更加充分，提高了传质效率，有利于降低产物抑制对酶活性的影响。本研究为提高木质纤维素原料均一性提供了一种有效的方法，对木质纤维素资源的开发具有重要意义。

关键词: 汽爆分级, 玉米秸秆, 酶解性能, 用酶量, 力学强度, 传质效率