Study on sterilization effect of ultraviolet light emitting diode on paddy surface Aspergillus flavus

Ultraviolet light emitting diode (UV-LED) treatment is a novel non-thermal sterilization technology. The focus of this study was to investigate the sterilization effect of UV-LED treatment on Aspergillus flavus artificially inoculated on the surface of paddy. Specifically, infected paddy was subjected to the treatment device. The number of A. flavus colonies on paddy was counted before and after treatment. Then, the antifungal efficiency of the apparatus against A. flavus on paddy was assessed. Meanwhile, the germination rate and fatty acid value of paddy were assessed to optimize the sterilization treatments for paddy storage. The results demonstrated that UV-LED treatment could significantly inhibit the growth of A. flavus on the surface of paddy. The rate of sterilization was significantly positively correlated with the exposure time, initial bacterial load on the paddy and device power, significantly negatively correlated with the distance from the light source. However, the moisture content of the paddy did not significantly affect the sterilization rate. When the treatment was applied at a power of 10 watts, at a distance of 5 cm for 90 minutes, the number of surviving A. flavus spores on the surface of paddy was reduced by 90%. Moreover, as the exposure time increased, the germination rate of the paddy showed an initial increase followed by a decline, while the fatty acid value remained unchanged. In conclusion, the UV-LED treatment shows great promise as a non-thermal sterilization technique. It is an effective physical technology for sterilizing and maintain quality before storage. The germination rate of the paddy, however, is influenced by the duration of the treatment. These findings provide valuable insights for the optimization of sterilization treatments prior to the storage of paddy, thereby potentially improving the quality and safety of stored paddy.