关键词: 大米, 淀粉, 分子量分布, 特征粘度

Abstract: The molecular weight distribution rule and intrinsic viscosity on rice starches were measured by gel permeation chromatography and Ostwald viscometer, respectively. The relationship between molecular weight distribution and intrinsic viscosity of rice starches was studied. Rice starch has 3 main fractions, amylose, intermediate and amylopectin. Relative molecular weight of rice amylopectins is about 89.58×106g/mol~1 559.76×106g/mol, while rice amyloses is about 4.06×106g/mol~6.85×106g/mol. The molecular weight distribution of rice amylopectin is narrower than rice amylose. The molecular weight distribution of intermediate is wider. The intrinsic viscosity of rice starches is about 77.65g/g~237.53g/g. When molecular weight and molar ratio of amylopectin are bigger, intrinsic viscosity is higher. But amylose with bigger molecular weight and higher molar ratio may make intrinsic viscosity to be lower. The relationship between rice molecular weight distribution and intrinsic viscosities of rice starches could be described accurately by an exponential model.

Key words: rice, starch, molecular weight distribution, intrinsic viscosity