Abstract The objectives of this work were to 1) determine the physical structure of untreated wheat bran and the differences in physical structure between its dissected layers; 2) evaluate how bran hydration affected bran crystallinity and polymer order; and 3) determine how enzymatic treatment of wheat bran affected its physical structure. For the first time, X-ray diffraction (XRD), small angle X-ray scattering (SAXS), solid-state 13C cross-polarization magic-angle spinning nuclear magnetic resonance (13C CP/MAS NMR), and polarized light microscopy with a waveplate were used to study the physical structure of wheat bran and its dissected layers. The XRD and solid-state 13C CP/MAS NMR both confirmed the presence of crystalline cellulose in untreated bran, enzymatically treated bran, and dissected bran layers. The outer pericarp had the highest crystallinity of the dissected bran layers and showed negative birefringence. The aleurone layer was low in cellulose content and completely amorphous, yet the cell walls in the aleurone layer showed strong positive birefringence. The treatment of destarched and deproteinated bran with the Updegraff reagent removed amorphous material, leaving its crystalline cellulose structure intact. Hydration of the outer pericarp increased its crystallinity index and CP/MAS NMR resonance intensity, which indicated a possible increase in polymer order. The SAXS also confirmed that cell wall polymers, possibly aggregated cellulose microfibrils, increased in order as a result of hydration.

中文翻译：

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麦麸及其解剖层中生物聚合物基质的物理特性

摘要 这项工作的目的是： 1）确定未经处理的麦麸的物理结构及其解剖层之间物理结构的差异；2) 评估麸皮水合如何影响麸皮结晶度和聚合物顺序；3) 确定酶处理麦麸如何影响其物理结构。首次采用 X 射线衍射 (XRD)、小角 X 射线散射 (SAXS)、固态 13C 交叉极化魔角自旋核磁共振 (13C CP/MAS NMR) 和偏光显微镜一个波片被用来研究麦麸及其解剖层的物理结构。XRD 和固态 13C CP/MAS NMR 都证实了在未处理的麸皮、酶处理的麸皮和解剖的麸皮层中存在结晶纤维素。在解剖的麸皮层中，外果皮的结晶度最高，并显示出负双折射。糊粉层纤维素含量低且完全无定形，但糊粉层中的细胞壁显示出强烈的正双折射。用 Updegraff 试剂处理脱淀粉和脱蛋白的麸皮去除了无定形物质，保持其结晶纤维素结构完整。外果皮的水化增加了其结晶度指数和 CP/MAS NMR 共振强度，这表明聚合物顺序可能增加。SAXS 还证实细胞壁聚合物，可能是聚集的纤维素微纤维，由于水合作用而有序增加。糊粉层纤维素含量低且完全无定形，但糊粉层中的细胞壁显示出强烈的正双折射。用 Updegraff 试剂处理脱淀粉和脱蛋白的麸皮去除了无定形物质，保持其结晶纤维素结构完整。外果皮的水化增加了其结晶度指数和 CP/MAS NMR 共振强度，这表明聚合物顺序可能增加。SAXS 还证实细胞壁聚合物，可能是聚集的纤维素微纤维，由于水合作用而有序增加。糊粉层纤维素含量低且完全无定形，但糊粉层中的细胞壁显示出强烈的正双折射。用 Updegraff 试剂处理脱淀粉和脱蛋白的麸皮去除了无定形物质，保持其结晶纤维素结构完整。外果皮的水化增加了其结晶度指数和 CP/MAS NMR 共振强度，这表明聚合物顺序可能增加。SAXS 还证实细胞壁聚合物，可能是聚集的纤维素微纤维，由于水合作用而有序增加。外果皮的水化增加了其结晶度指数和 CP/MAS NMR 共振强度，这表明聚合物顺序可能增加。SAXS 还证实细胞壁聚合物，可能是聚集的纤维素微纤维，由于水合作用而有序增加。外果皮的水化增加了其结晶度指数和 CP/MAS NMR 共振强度，这表明聚合物顺序可能增加。SAXS 还证实细胞壁聚合物，可能是聚集的纤维素微纤维，由于水合作用而有序增加。