Gamma-radiation Effects on Taiwan-produced Rice-grains

Abstract
Gamma-radiation effects on Taiwan-produced rice-grains have been investigated and discussed to find an advantageous application of radiation processing on the preservation of rice-grains. This paper deals with the results obtained from the three major kinds of rice-grains which were gamma-irradiated and stored. The factors of contaminated microorganisms on the rice-grains, chemical analysis of rice-ingredients, activity of α-amylase in the rice-grains, germination-rate of the rice-grains, rice-insect fertility and cooking quality of the hulled rice were studied. Among them, the following factors were considered as the main results. 1. Gamma-irradiation could reduce the contaminated microorganisms remarkably as the gamma-dose was raised over 100 krad, e.g., reduction of the survivals of microorganisms to 19.62 ~ 39.76% with 100 krad, to 5.41 ~ 9.09% with 300 krad, to 0.58 ~ 0.81% with 1 Mrad during the twelve months storage period. 2. Some fluctuations on the fat acidity and the contents of reducing sugars and thiamine in the irradiated rice-grains were observed in the period of twelve months preservation at 20 ~ 30°C. 3. The germination of rice-grains was reduced considerably with the irradiated samples exposed to a gamma-dose over 50 krad. 4. No deleterious effects on rice-insect fertility on the irradiated rice-grains with a 50 krad gamma-dose occurred during the twenty-four months storage period, unlike those of the unirradiated ones and the irradiated ones with gamma-doses below 30 krad. 5. No significant changes were found on the cooking quality of the hulled rices irradiated below a gamma-dose of 300 krad and stored for twenty-four months at 20 ~ 30°C.