水稻籽粒鲜样品的直链淀粉含量测定方法

Method for determining amylose content of fresh rice sample.

分析了 p H值、样品浓度等因素对稻米直链淀粉含量测定的影响 ,提出以标准样品在 62 0 nm处的吸光度和相应的总淀粉浓度为自变量、相应的直链淀粉浓度为依变量建立标准回归方程的测定方法 .当样品的直链淀粉浓度在 5～ 5 0 mg/ L的范围内时 ,测定的相对偏差 <3%、变异系数 <2 .5 % .该方法样品用量少 ,操作简便 ,且能消除支链淀粉的干扰 ,可以同时测定直、支链淀粉含量 ,尤其适用于水稻籽粒鲜样品中直链淀粉含量的测定 .

Based on the effects of pH and sample concentration on determination of amylose content of rice sample, a new method for the determination was developed. A multivariate regression equation was formulated which reflects the relation of amylose content to starch concentration and absorbance at 620 nm of rice sample and permits the amylose content of rice sample to be calculated from the data of absorbance. Using this method, the interference from amylopectin during determination was eliminated and both amylose content and amylopectin content of rice sample could be obtained. Amylose content in the range of 5 50 mg/L could be determined with a relative deviation of less than 3 per cent and the C.V. was below 2.5 per cent. The far less amount of rice sample needed than that used in the classical method as suggested by Juliano in 1971 and simplicity in performance were the other advantages of the method. The method can be particularly adapted to determine the amylose content of fresh rice sample where the quantity available is limited.