Comparative structure and physicochemical properties of Ilpumbyeo, a high-quality japonica rice, and its mutant, Suweon 464.

A new rice mutant Suweon 464 (S-464) derived from a high-quality rice, Ilpumbyeo (IP), revealed a striking difference in cooking quality from IP. The physicochemical properties of S-464 and IP were compared. S-464 was unusually high in amylose and fiber contents, had B-type crystallinity of starch, and had a markedly lower proportion of short chains in the distribution of glucan-chain fractions of debranched starch as compared with IP. Scanning electron microscopy revealed that starch granules of S-464 were much smaller in size than those of IP and that many of them were not separated from amyloplasts. The physicochemical properties of S-464 would contribute to poor gelatinization, lower swelling power, higher hardness, and less stickiness when cooked. Although S-464 may not be desirable for cooked rice, the mutant could be an excellent candidate for other processed food products on the basis of its unusual properties of starch and high fiber, protein, and lipid contents.