该研究以米糠为原料，分别采用挤压膨化、米根霉发酵及发酵-挤压膨化技术处理制备米糠可溶性膳食纤维（Soluble Dietary Fiber，SDF），分析其SDF的微观结构、吸收峰特征、分子量和单糖组成，并进行抗氧化活性评价。结果表明，3种加工方式均显著增加了SDF含量，较未处理的SDF分别提高了51.49%、108.63%、118.15%；经加工处理后的米糠SDF的微观结构更为疏松多孔且分子量更低；4种米糠SDF具有相似的特征吸收峰，但其吸收峰强度存在一定差异。与未处理的米糠SDF相比，米根霉发酵及其联合挤压膨化处理的米糠SDF出现岩藻糖结构片段，且其鼠李糖、阿拉伯糖、木糖、甘露糖和半乳糖含量比例更高，而经挤压膨化处理后其葡萄糖含量更高；此外，挤压膨化和发酵的米糠SDF具有更高抗氧化活性，但二者联合处理的SDF抗氧化活性无显著差异。综合比较发现经三种加工处理的米糠SDF具有显著的结构差异及增强抗氧化活性能力，其中发酵处理对米糠SDF的影响最显著，该研究对开发米糠加工新工艺以制备高活性米糠SDF具有指导意义。

Rice bran soluble dietary fibers (SDF) were obtained from rice bran by extrusion, fermentation with Rhizopus oryzae, and fermentation-extrusion. The microstructure, absorption peak characteristics, molecular weight, and monosaccharide composition of the rice bran SDFs were examined, and their antioxidant activities evaluated. The three processing methods significantly increased the SDF content to 51.49%, 108.63%, and 118.15% as compared to unprocessed SDF. Additionally, there was an increase in the number of porous microstructures observed following processing, along with a decrease in molecular weight. The four types of rice bran SDFs exhibited similar characteristic absorption peaks, but at different intensities. Compared to the unprocessed rice bran SDFs, SDFs prepared by fermentation and fermentation-extrusion contained structural fucose fragments and had higher rhamnose, arabinose, xylose, mannose, and galactose content. Meanwhile, a higher glucose content was observed in the extruded rice bran SDFs. Both extruded and fermented SDFs exhibit improved antioxidant activities, while no change was observed in the fermentation-extrusion-generated SDFs in terms of antioxidant activity. Comprehensive comparison revealed that SDFs prepared from these three processing methods had significant structural differences and enhanced antioxidant activity as compared to SDFs from unprocessed bran. Fermentation had the most significant effect on the SDFs. This study is of significance in developing new rice bran processing technology for the preparation of highly active rice bran SDFs.

国家自然科学基金项目（31972082）；珠海市科技计划项目（ZH22036201210043PWC）；中央引导地方（南雄）科技发展资金项目；广东省农业科学院中青年学科带头人培养计划（R2020PY-JG011）；广东省农业科技创新推广项目（粤财农[2021]170号）