Decontamination of black peppercorns using UV-LED technology and its effect on cell viability

Ultraviolet light-emitting diodes (UV-LEDs) are being investigated for potential use in food disinfection due to their customisable wavelength and high energy efficiency. The objective of this study was to examine the impact of UV-LED treatments, for up to 30 min, at wavelengths of 280, 300, and 365 nm, as well as simultaneous irradiation with 280 and 300 nm, on the culturability of Escherichia coli, Bacillus cereus spores, and Salmonella enterica in black peppercorns. It resulted in a reduction of up to 1.65, 1.35 and 1 log colony-forming units per gram (CFU/g) for E. coli, S. enterica, and B. cereus spores, respectively. The viability of S. enterica was also evaluated in black pepper using a viability PCR method with DyeTox13. No significant differences were observed between active and inactive non-culturable states. This finding suggests that UV light did not cause substantial lethal damage to the bacteria, but instead rendered them non-culturable, potentially leading to an underestimation of the food safety risk. These findings are encouraging concerning the potential applications of UV-LEDs in the spice industry.