豆渣汽爆改性及其强化高固酶解作用研究

目的:采用汽爆解离改性联合高固酶解制取豆渣可溶性膳食纤维（soluble dietary fiber，SDF），研究汽爆对豆渣的改性作用及对其高固酶解过程的强化作用。方法:采用汽爆技术改性处理豆渣，应用扫描电镜、傅里叶红外光谱和差示量热扫描等技术对豆渣改性前后的微观形貌、化学组成与官能团结构、热稳定性进行表征分析；再将汽爆豆渣进行高固酶解转化制取SDF，对比分析汽爆前后豆渣酶解效果。结果:汽爆处理可明显改善豆渣结构与性质，促进不溶性膳食纤维（insoluble dietary fiber，IDF）向SDF转化，最佳汽爆强度条件下豆渣SDF含量提高至原料的3.85倍；汽爆后豆渣微观呈现疏松蜂窝状多孔结构，水溶性提高5.13倍，持水性、持油性和浸水溶胀性降低；汽爆后豆渣最大热解峰温度和焓变值均提高，热稳定性增加。汽爆通过改善上述酶解底物组成结构和体系流动状态，降低豆渣高固酶解过程固体载荷制约，从而提高酶解底物浓度、降低酶用量、缩短酶解时间。在最高固体载荷20%和最低用酶量5 FPU/g的酶解条件下，汽爆豆渣中SDF得率达到43.75%，与原料相比提高3.76倍；汽爆后豆渣高固体载荷条件下酶解反应平衡时间缩短50%左右。结论:汽爆解离改性联合高固酶解处理技术为大量豆渣原料的高效转化和高值利用提供技术支持。

Steam Explosion Modification of Soybean Dregs to Enhance High-solid Enzymatic Hydrolysis Efficacy

Objective: The modification of bean dregs by steam explosion (SE) combined with high solids enzymatic digestion to extract soluble dietary fiber (SDF) was investigated to evaluate the modification effect of soybean dregs and the enhancement of the high solid enzymatic digestion process. Methods: The bean dregs were modified by SE technology. The microstructure, chemical composition, functional groups and thermal stability of bean dregs before and after SE modification were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. SDF was prepared by SE combined with high-solid enzymatic hydrolysis, and the enzymatic hydrolysis effect of bean dregs before and after SE was compared. Results: The SE treatment significantly improved the structure and properties of soybean dregs, which contributed to the conversion of insoluble dietary fiber (IDF) into SDF. The SDF content of soybean dregs was increased to 3.85 times that of raw materials under the optimal SE condition. After SE, the microstructure of bean dregs showed a loose honeycomb porous structure, the water solubility was increased by 5.13 times, and the water holding capacity, oil holding capacity and water swelling were reduced. The maximum pyrolysis peak temperature and enthalpy change of soybean dregs were increased and the thermal stability was improved. The composition and structure of enzymatic substrates and the flow state of enzymatic system were prompted by SE, so as to reduce the solid load restriction of enzymatic hydrolysis process of soybean dregs. It benefited to increase the concentration of the enzymatic substrate, lower the amount of enzymes and the enzymatic hydrolysis time. Under the enzymatic hydrolysis conditions at the maximum solid loading of 20% and the minimum enzyme consumption of 5 FPU/g, the yield of SDF in SE bean dregs reached 43.75%, which was 3.76 times higher than that of raw materials. Through SE, the reaction equilibrium time of enzymatic hydrolysis was decreased by about 50%. Conclusion: SE modification combined with high-solid enzymatic hydrolysis treatment technology would provide technical support for the efficient utilization and application for the large amount of bean dregs.