Changes of chemical components of wash-free milled rice during cooking, and palatability of cooked rice

Abstract

The surface structure and chemical components of the wash-free milled rice (cultivar : Koshihikari and Hinohikari) by bran grind method and the common milled rice (raw material for wash-free milled rice) were studied. Chemical components and palatability of their cooked rice was studied. The following results on the wash-free milled rice were obtained in comparison with the common milled rice : 1) The surface structure differed between them. The starch grains in the cells were exposed on the surface of the wash-free milled rice. On the other hand, bran adhered to the surface of the common milled rice. 2) Contents of ash, minerals (especially Mg and Fe, except Cu), thiamin and niacin were low in the wash-free milled rice. 3) Contents of minerals (Ca, Na, K, Zn and Cu), riboflavin and niacin were high in the cooked wash-free milled rice. 4) By cooking, chemical components almost did not changed in the wash-free milled rice. On the other hand, ash, minerals and water-soluble vitamins were lost in common milled rice because of washing with water. 5) The value of brightness (L-value) was a little high in the wash-free rice and its cooked rice. 6) The evaluation on whiteness, transparency, gloss and color in appearance were high in the cooked wash-free rice (especially Koshihikari).