Synergistic effect of the combined treatment with gamma irradiation and sodium dichloroisocyanurate to control gray mold (Botrytis cinerea) on paprika

Abstract

Gray mold (Botrytis cinerea) is one of the most major fungal pathogens in paprika. Generally, gamma irradiation over 1kGy is effective for the control of fungal pathogens; however, a significant change in fruit quality (physical properties) on paprika was shown from gamma irradiation at over 0.6kGy (p<0.05). Therefore, in this study, the synergistic disinfection effect of the combined treatment with gamma irradiation and sodium dichloroisocyanurate (NaDCC) was investigated to reduce the gamma irradiation dose. In an artificial inoculation experiment of B. cinerea isolated from naturally-infected postharvest paprika, fungal symptoms were observed in the stem and exocarp of paprika after conidial inoculation. From the sensitivity of gamma irradiation and NaDCC, B. cinerea conidia were fully inactivated by 4kGy of gamma irradiation (D10 value 0.99kGy), and were fully inactivated by 50ppm NaDCC treatment. The fungal symptoms were not detected by the dose-dependent gamma irradiation (>4kGy) and NaDCC (>50ppm). As a result of the combined treatment of gamma irradiation and NaDCC, the D10 value was significantly reduced by 1.06, 0.88, 0.77, and 0.58kGy (p<0.05). Moreover, fungal symptoms were more significantly reduced in combined treatment groups (gamma irradiation and NaDCC) than single treatment groups (gamma irradiation or NaDCC). These results suggest that combined treatment with irradiation and NaDCC treatment can be applied to preserve quality of postharvest paprika or other fruits.