Effect of Pectin Contents and Polygalacturonase Activity on Cooked Rice Texture

Abstract

　The effect of the pectin decomposition in cooking rice was investigated. Samples were nine types of non-glutinous japonica and indica, we measured pectin content of the milled rice, as well as cooked rice and the polygalacturonase (PG) activity. Pectin content was 291～133 mg/kg (dry weight) in the milled rice and 179～89 mg/kg (dry weight) in the cooked rice. The short-grain japonica rice of non-glutinous type had more pectin than indica one. The pectin decreased by 40.7～33.3 % in cooking rice. PG activities of the samples were 35～23 U/g (fresh weight). The extent of decomposition of pectin was correlated to the values of hardness of cooked rice (r＝－0.800, p＜0.05) and the PG activities of milled rice (r＝0.677, p＜0.05).