UV-C treatment for the inhibition of molds isolated from dried persimmons (Diospyros kaki L.) and modelling of UV-C inactivation kinetics

Ultraviolet (UV-C) is one of the alternative non-thermal technologies used for the surface decontamination of many foods. The aim of this study was to evaluate the effects of UV-C treatment on molds isolated from dried persimmons and also to determine the inactivation kinetics of selected UV-C resistant mold cultures. UV-C resistant fungal strains identified by using molecular methods were Rhizopus oryzae, Aspergillus niger and Alternaria tenuissima. UV-C resistant fungal spore suspensions were subjected to UV-C at doses of 0.6-18 kJ/m(2) under in vitro conditions to characterize the inactivation kinetics. UV-C treatment at 0.6 kJ/m(2) significantly reduced the numbers of test molds (P < 0.05). Results revealed that R. oryzae was the most sensitive microorganism among the selected strains, whereas higher UV-C doses of 6 and 18 kJ/m2 were required to eliminate A. niger and A. tenuissima, respectively. The inactivation kinetics of R. oryzae, A. niger and A. tenuissima were best described by Biphasic + shoulder, Biphasic and Log lineer + tail models, respectively. Predicted values were in close agreement with the experimental values with R-2 of higher than 0.98 and RMSE lower than 0.12. In the present study, UV-C resistant molds, that can be used as target microorganisms for the establishment of UV-C process schedule for dried persimmons, were selected and identified.