Effects of UVC light-emitting diodes on inactivation of Escherichia coli O157:H7 and quality attributes of fresh-cut white pitaya

The work aimed to evaluate the effects of ultraviolet-C light-emitting diodes (UVC-LEDs) at 275 nm against Escherichia coli O157:H7 on fresh-cut white pitaya. Besides, the influences of UVC-LED treatments on the quality of fresh-cut white pitaya were also investigated. The distance between the UVC-LEDs and the surface of the pitaya pieces was approximately 5 cm. The inactivation behavior of E. coli O157:H7 on fresh-cut pitaya began almost instantaneously and then tailed off as the fluence increased. The quantities of E. coli O157:H7 inoculated on fresh-cut white pitaya were reduced by 2.21 lg(10) CFU/g after UVC-LED treatment at 1200 mJ/cm(2) (33 min). The Weibull plus tail model was satisfactorily fitted to estimate the reduction of E. coli O157:H7 on fresh-cut white pitaya, with the R-2 and root mean square error (RMSE) reached 0.99 and 0.05, respectively. Physicochemical properties (pH, total soluble solids, and total phenolic content) and color parameters of fresh-cut pitaya did not change significantly after UVC-LED treatment. However, UVC-LED treatment at a higher fluence led to a small reduction of antioxidant properties. These results indicate that UVC-LEDs emitting at 275 nm may improve the microbiological safety and maintain the qualities of fresh-cut fruit. Moreover, the synergy of UVC-LEDs with other preservation methods would have a potential application in the fresh-cut fruit processing industry to present enhanced inactivation efficiency and to better maintain the nutritional and sensory qualities of fresh-cut fruits.