Abstract
Waxy mutants induced by mutagens in O. sativa (cv. "Norin 8", "Reimei" and "Nihonmasari") and "O. glaberrima" were investigated for their processing suitability for rice-cake. To confirm their processing properties in response to the ripening temperature, mutants were cultivated under two different ripening conditions, namely ordinary and late transplanting. In the waxy mutant strain derived from "O. glaberrima" the rice-cake showed a very high hardness and pasting temperature compared with "Koganemochi", whereas in the other strains, the rice-cake showed a lower hardness than that of commercial varieties. In most of the strains derived from "Nihonmasari", the hardness of the rice-cake decreased when the ripening temperature increased. It was also observed that, in several strains derived from "Reimei", waxy starch viscosity was remarkably high regardless of the low rice-cake hardening. Although the ripening temperature of the waxy mutants derived from a variety was almost identical, the hardness of the rice-cake, heat gelatinization properties and apparent amylose content were markedly different among the strains. It is considered that the induced waxy mutants with distinguishing traits could become useful breeding materials for the manufacture of new rice processing foods and would be suitable for various processed products required by the rice processing industries.
