USDA-ARS CGAHR, Manhattan, KS 66502, USA.
J Sci Food Agric. 2013 Mar 30;93(5):1233-41. doi: 10.1002/jsfa.5890. Epub 2012 Sep 25.
Tannins are large polyphenolic polymers and are known to bind proteins, limiting their digestibility, but are also excellent antioxidants. Numerous studies investigating the functional properties of sorghum tannin have been conducted by comparing grain samples from different sorghum lines without considering the other intrinsic characteristics of the grain. The purpose of this study was to remove the confounding intrinsic factors present in the endosperm so the effect of the tannins could be evaluated utilizing a unique decortication/reconstitution procedure.
The tannin content of the 14 cultivars tested ranged from 2.3 to 67.2 catechin equivalents. The bran fractions were studied for their impact on protein binding and antioxidant capacity. Protein digestibility by pepsin ranged from 8% to 58% at the highest tannin level addition. Protein binding ranged from 3.11 to 16.33 g blue bovine serum albumin kg⁻¹ bran. Antioxidant capacity ranged from 81.33 to 1122.54 µmol Trolox equivalents g⁻¹ bran. High-performance size-exclusion chromatography detailed molecular size distributions of the tannin polymers and relationship to tannin functionality.
The tannin content and composition play a significant role in determining tannin functionality. These differences will allow for selections of high-tannin sorghums with consideration of the biological activities of the tannins.
单宁是一种大型多酚聚合物，已知会与蛋白质结合，从而限制其可消化性，但它也是一种极好的抗氧化剂。许多研究通过比较不同高粱品系的谷物样本来研究高粱单宁的功能特性，而没有考虑到谷物的其他内在特性。本研究的目的是去除胚乳中存在的混杂内在因素，以便利用独特的去皮/重组程序来评估单宁的作用。
在所测试的 14 个品种中，单宁含量范围为 2.3 到 67.2 没食子儿茶素当量。研究了麸皮部分对蛋白质结合和抗氧化能力的影响。在最高单宁水平添加下，胃蛋白酶对蛋白质的消化率范围为 8%至 58%。蛋白质结合范围为 3.11 至 16.33 g 蓝牛血清白蛋白 kg-1 麸皮。抗氧化能力范围为 81.33 至 1122.54 μmol Trolox 当量 g-1 麸皮。高效尺寸排阻色谱详细描述了单宁聚合物的分子大小分布及其与单宁功能的关系。
单宁含量和组成在决定单宁功能方面起着重要作用。这些差异将允许选择具有高单宁的高粱，同时考虑到单宁的生物活性。
