γ線と紫外線を照射した農産物腐敗性藻菌類の生存曲線の数量的解析

抄録

It is expected that gamma (γ) and ultraviolet (UV) rays are applicable to sterilize agricultural products for reducing storage losses. In practical application, D₁₀-and D_99.9-value in γ and UV irradiation have been used as sterilization indices. However, our preliminary results showed that these survival curves were exponential having a shoulder at a beginning in many strains of molds. This suggests the difficulty in assessing a sterilization level accurately using these indices.
The survival curves of several molds infecting agricultural products for γ irradiation were simulated with a multi hit theory in molecular radiation biology. On the other hand, the effect of UV irradiation on the survival curves was simulated by multi hit theory, taking into account the decrease in UV-intensity in liquid suspensions due to Lambert's law. It was found that the models based on a multi hit theory well simulated the effects of γ and UV irradiation. Among molds tried in this study, the four hits model best fit to the observed data in cases of Phycomycetes.
These results demonstrated that D₁₀-and L-values, instead of conventional indices based on D₁₀-and D_99.9-values, should be used to assess the sterilization level accurately. To obtain more reliable measurement, a target area and a hit number, a parameter of penetration in UV-sterilization should be taken into considerations.