1953 年 18 巻 1-2 号 p. 41-45
1. 29 strains of mold were isolated from samples of stored rice grain, of which moisture content had been contro led in several grades. Of the molds Pencillium and Aspergillus were most prevalent (table 2).
2. The most vigorous development of molds was observed at 20°C during incubation and poor at 10°C and 30°C.
3. The largest number of strains were isolated from grains with 18% moisture, the next was from grains of 20% and 16% moisture.
4. Osmotic pressure of spore of the isolated molds exists between 19.6 and 134.8 atmospheric pressure, being the maximum value 6.9 times of the minimum value.
5. It was observed that osmotic pressure of the molds isolated from rice grains lowest moisture content gave the highest value. According as moisture of rice increased, osmotic pressure of the associated molds decreased. So the strain of mold grown on the rice is mainly decided by the actual moisture content of the rice.
6. The osmotic pressure of the rice grain determined on embryo and aleurone layer came to be lower in inverse proportion to the rice moisture content.
7. It seems necessary for molds to grow on the rice grain that their osmotic pressure should be more than about 5 times higher than that of rice. The osomtic pressure of molds does not reach to 5 times of that of rice with 14.5% moisture on which, the molds can scarcely grow.
8. As the conclusion, it is necessary to dry rice grain to a moisture content below 14.5%, in order to prevent mold growth.