Application of ultraviolet-C light on oranges for the inactivation of postharvest wound pathogens

Germicidal effects of ultraviolet-C (UV-C) light on the postharvest wound pathogens of citrus fruits namely Penicillium digitatum and Penicillium italicum were investigated. P. digitatum and P. italicum spores were inoculated (4.00-4.50 log cfu/orange) onto Washington navel oranges (Citrus sinensis L. Osbeck cv Washington navel) by using wound and spot inoculation methods and subjected to eight different UV-C doses in the range of 0.26-15.84 kJ/m2. Maximum reductions of 2.75 and 3.33 log cfu/orange of P. digitatum were obtained at the UV-C dose of 3.17 kJ/m2 for spot and wound inoculation methods, respectively. P. italicum was more resistant than P. digitatum to UV-C treatments. The results suggest that UV-C treatments designed to reduce P. italicum spores will provide an adequate degree of protection against P. digitatum spores. UV-C light could be an alternative technique for the use of synthetic chemicals to reduce the development of postharvest pathogens of oranges.