Comparative Studies on the Unit Chain Distributions of Endosperm Starch of Ancient-type, Pigmented Rice Grains, and Their Antioxidant Activities

Abstract

Distributions of α-1,4 unit chains of the endosperm starch molecules of so-called ancient-type, pigmented rice grains were precisely analyzed by HPAEC, after enzymic debranching of their amylopectin fractions, and compared with those of cultivated, ordinary Japanese rice, and also of various non-kernel cereals. The results show that the unit chain of color pigmented rice starches are distributed DP 6 to 30 with high proportions of DP 10-12 peak, similar to those of other cereal starches, suggesting that the rice endosperm starches, used as main energy-supplied source would not significantly different during human long history. In the present studies we noted that, in the case of rice starch, the unit chain of amylopectin of the endosperm starch, might be shifted significantly to longer, as milling degrees are increased, as in the case of 10 %, 40 %, and 60 % milled Yamadanishiki rice, which would affect to sake-fermentation. The antioxidant activity in the bran fraction of red color pigmented rice grain was also confirmed.