小麦麸皮木聚糖理化性质及抗氧化活性研究

小麦麸皮是天然可再生的农业副产品,其中木聚糖是小麦麸皮中非淀粉多糖的主要成分,具有优良的理化特性和生理活性；但小麦麸皮多作为醋、酱油或饲料等其他廉价产品的原料,造成了资源浪费。通过对小麦麸皮高温蒸煮液进行乙醇分级沉淀,得到4种木聚糖组分(EXy40、EXy60、EXy80、EXy90),对各组分进行单糖组成分析、相对分子质量测定、红外光谱分析；考察了酶解对4种木聚糖组分体外抗氧化活性的影响。结果表明:4种木聚糖组分的相对分子质量分布较窄,多分散性系数较小；经改性后,体外抗氧化活性均有显著增强,其中EXy40、EXy80和EXy90三种组分的羟自由基清除率达到97%以上。研究以期为小麦麸皮的综合开发利用及深入探索小麦麸皮木聚糖的构效关系,提供一定的理论依据。

Study on Physicochemical Properties and Antioxidant Activity of Xylan Extracted from Wheat Bran

Wheat bran is a natural and renewable agricultural by-product. Among them, xylan is the main component of non-starch polysaccharides in wheat bran and has excellent physicochemical properties and physiological activities. Wheat bran is mostly used as a raw material for other cheap products such as vinegar, soy sauce or feed, resulting in a waste of resources. Xylan was prepared by different gradient concentrations of ethanol from wheat bran high-temperature cooking liquor and four precipitation fractions were obtained, which were EXy40, EXy60, EXy80 and EXy90. Monosaccharide compositions, relative molecular weight and infrared spectrum of four kinds of xylan were determined. Moreover, effects of enzymatic modification on the in vitro antioxidant activities of xylans were investigated. As a result, the relative molecular weight distribution of the four xylan components was narrow and the polydispersion coefficient was small. The in vitro antioxidant activities of the four xylan components were significantly enhanced after enzymatic hydrolysis. The scavenging effect on hydroxyl radical was improved, and the removal rate of EXy40, EXy80 and EXy90 could reach more than 97%. This study might provide a certain theoretical basis for the comprehensive development and utilization of wheat bran and the in-depth study of the structure-activity relationship of xylan extracted from wheat bran.