Correlation between Taste of Cooked Rice and Structural Characteristics of Rice Starch

Abstract

Using three rice varieties with different tastes and newly developed rice varieties as samples, the relation between the texture of cooked rice (white rice) and starch structure was examined. The amylose contents of the rice starches ranged from 6.3 to 27.3% on gel filtration. The chain length distribution of amylopectins indicated that Fr.II ranged from 17.3 to 25.3% and Fr.III/Fr.IIratios ranged from 2.7 to 3.2. Rice starch with a lower amylose content showed a lower Fr.III/Fr.II ratio. The chain length distribution of amylopectins proved that amylopectin from favorable white rice showed a small amount of Fr. I and a large amount of Fr.II as well as a low Fr.III/Fr.II ratio. The average chain length of amylopectins, as determined by modified SMITH's degradation method, ranged from 18.2 to 23.1. These values agreed well with those determined by the enzymatic method. Rice starch having a low amylose content showed a shorter average chain length. White rice significantly differed in physicochemical properties and sensory evaluation, especially in firmness and adhesiveness by rice variety. Thus, the taste of white rice appeared to be closely related to the structure of the rice starch.