Abstract
To observe the effect of 30°C storage on microorganisms on irradiated rice, unpolished and polished rice harvested in Japan were used as the samples. The storage life of polyethylene-packed rice containing 14-15% moisture was extended by 3-4 times by means of 0.2 Mrad irradiation. The number of molds on the irradiated rice grains was not increased for 3-4 months under this condition. When the moisture in the rice sample was 17%, more than 0.4 Mrad was necessary to extend its storage life.
The species of molds which can propagate on storage-rice grains containing 17% moisture were mainly Aspergillus glaucus group and Penicillium citrinum series, where Asp. restrictus, Asp. vercicolor, Asp. candidus, etc. were minor ones. When moisture content was 16%, Asp. glaucus group and Asp. restrictus were observed. Only the halophilic species of Asp. restrictus was the species of molds which propagated on the rice sample containing 14-15% moisture.
When a sheet of porous material, e.g. craft paper bag, was used to pack rice, the storage life of rice containing the moisture of less than 15% was extended by 3-4 times by means 0.2 Mrad irradiation, the storage conditions being 30°C 75% relative humidity. In this case the number of molds on rice was not increased for 3-4 months under this condition.
