Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Zhongshan Biological Breeding Laboratory, Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Agriculture, Yangzhou University, Yangzhou 225009, China; The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, Brisbane, QLD 4072, Australia.
Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Zhongshan Biological Breeding Laboratory, Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Agriculture, Yangzhou University, Yangzhou 225009, China.
Carbohydr Polym. 2024 Sep 1;339:122264. doi: 10.1016/j.carbpol.2024.122264. Epub 2024 May 12.
Normal rice starch consists of amylopectin and amylose, whose relative amounts and chain-length distributions (CLDs) are major determinants of the digestibility and rheology of cooked rice, and are related to metabolic health and consumer preference. Here, the mechanism of how molecular structural features of pure amylopectin (waxy) starches affect starch properties was explored. Following debranching, chain-length distributions of seven waxy varieties were measured using size-exclusion chromatography, and parameterized using biosynthesis-based models, which involve breaking up the chain-length distribution into contributions from five enzyme sets covering overlapping ranges of chain length; structure-property correlations involving the fifth set were found to be statistically significant. Digestibility was measured in vitro, and parameters for the slower and longer digestion phase quantified using non-linear least-squares fitting. The coefficient for the significant correlation involving amylopectin fine structure for the fifth set was -0.903, while the amounts of amylopectin short and long chains were found to dominate breakdown viscosity (correlation coefficients 0.801 and - 0.911, respectively). This provides a methodology for finding or developing healthier starch in terms of lower digestion rate, while also having acceptable palatability. As rice breeders can to some extent control CLDs, this can help the development of waxy rices with improved properties.
普通稻米淀粉由支链淀粉和直链淀粉组成，其相对含量和链长分布（CLD）是决定米饭消化率和流变特性的主要因素，与代谢健康和消费者偏好有关。在这里，我们探讨了纯支链淀粉（蜡质）淀粉的分子结构特征如何影响淀粉性质的机制。在支链酶解后，使用凝胶渗透色谱法测量了七种蜡质品种的链长分布，并使用基于生物合成的模型进行参数化，该模型涉及将链长分布分解为涵盖链长重叠范围的五组酶的贡献；发现涉及第五组的结构-性质相关性具有统计学意义。在体外测量了消化率，并使用非线性最小二乘法拟合定量了较慢和较长消化阶段的参数。涉及第五组支链淀粉精细结构的显著相关的系数为-0.903，而支链淀粉短链和长链的含量则主导了崩解粘度（相关系数分别为 0.801 和-0.911）。这为寻找或开发具有较低消化率的更健康淀粉提供了一种方法，同时也具有可接受的口感。由于稻米育种者在一定程度上可以控制 CLD，因此这有助于开发具有改良特性的蜡质稻米。
