Effects of ethanol and ultraviolet-c treatments on inactivation of Rhizopus oryzae spores which cause postharvest rot

Abstract Rhizopus oryzae is a filamentous fungi reported as a postharvest pathogen in recent years. Ethanol treatment (0, 10, 20, and 30%) and UVC irradiation (0, 1, 2, 5, 10 minutes) were used both individually and in combination for the inactivation of Rhizopus oryzae spores. Survival ratio of the spores and LD50 values for ethanol and UVC irradiation were determined to quantify the germicidal effect. UVC exposure is found to be significantly more effective than ethanol treatment on the reduction of R. oryzae spore survivability. The combination of UVC exposure and ethanol treatment enhanced the lethality of applying each treatment separately and the enhancement increased as the UVC exposure time and ethanol concentrations increased. The lowest spore survival ratio was 0.015%, obtained after 30% ethanol treatment followed by 10 minute of UVC exposure. These observations suggest that ethanol treatment and UVC exposure can effectively be used as a possible strategy to inactivate R. oryzae spores.