Joint International Research Laboratory of Agriculture and Agri-Product Safety, College of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, China; The University of Queensland, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, Brisbane, QLD, 4072, Australia.
Joint International Research Laboratory of Agriculture and Agri-Product Safety, College of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, China.
Carbohydr Polym. 2019 Jan 15;204:24-31. doi: 10.1016/j.carbpol.2018.09.078. Epub 2018 Oct 1.
Starch molecular fine structure can have significant effects on pasting and thermal properties of rice flour. This study investigates the mechanistic explanation of these effects, by obtaining data for rice flour with different starch fine structures. Starch structural parameters for both amylose and amylopectin were obtained using size-exclusion chromatography (SEC, a type of gel-permeation chromatography, GPC), and the data fitted with methodologies (one of which is new) based on the underlying biosynthetic processes. It is found that the setback viscosity of rice starch measured by the rapid viscosity analyzer (RVA) depends not only on amylose content but also on the amount of long amylose chains and the size of whole amylopectin molecules. Conversely, long amylose chains and large amylopectin molecules are found to be responsible for the lower peak and trough viscosities. Other results for the effects of amylopectin chains are consistent with the literature. Mechanistic explanations for all observations are put forward. The novel findings about the influence of the distribution of amylose chain lengths and whole amylopectin size, in addition to amylose content alone, can provide guidance for rice breeders and food scientists in the selection of rices with improved functional properties.
淀粉分子的精细结构会对米粉的糊化和热性质产生重大影响。本研究通过获得具有不同淀粉精细结构的米粉数据，探究这些影响的机制解释。使用尺寸排阻色谱法（SEC，一种凝胶渗透色谱法，GPC）获得直链淀粉和支链淀粉的淀粉结构参数，并根据潜在的生物合成过程，使用基于该过程的方法（其中一种是新方法）对数据进行拟合。结果发现，快速粘度分析仪（RVA）测量的大米淀粉的回生值不仅取决于直链淀粉含量，还取决于长直链淀粉链的数量和整个支链淀粉分子的大小。相反，长直链淀粉链和大支链淀粉分子会导致较低的峰值和低谷粘度。关于支链淀粉链影响的其他结果与文献一致。对所有观察结果提出了机制解释。关于直链淀粉链长度分布和整个支链淀粉大小的新发现，除了直链淀粉含量之外，还可以为水稻种植者和食品科学家在选择具有改善功能特性的大米方面提供指导。
