Inactivation of Foodborne Pathogens on Stainless Steel Surfaces Using Ultraviolet Light−Emitting Diodes (UVC-LED) and Ultrasonic Aerosolization with GRAS Agents

The inactivation of Listeria monocytogenes and Escherichia coli on stainless steel surfaces was evaluated using a combination of ultraviolet light-emitting diodes (UVC-LED) and ultrasonic aerosolization with generally recognized as safe (GRAS) agents: sodium hypochlorite (NaOCl), acetic acid (AA), and hydrogen peroxide (H₂O₂). Stainless steel coupons (2 cm in diameter) inoculated with 6-7 log CFU/coupons of both pathogens were used as bioindicators. Coupons were treated with: UVC-LED (275 nm) at 2 and 4 cm distance for 5, 10, and 15 min; ultrasonic aerosolization with NaOCl, AA, or H₂O₂ for 5, 10, and 15 min or with combinations of both technologies. Lethality, sublethal damage, and cell leakage were evaluated. Results showed that UVC-LED treatments were more effective at doses of 30.42 mJ/cm² (shorter distance at 2 cm and longer exposure time 15 min), achieving significant reductions in L. monocytogenes (2.27 log CFU/coupon). The aerosolized GRAS agents were also effective, especially at the highest concentrations and longer exposure times, achieving complete inactivation of both bacteria. Combining UVC-LED (5, 10, 15 min) with 0.3% H₂O₂ aerosolization resulted in a more effective inactivation at lower doses, highlighting the potential of these combined technologies to improve food safety on food contact surfaces in the food industry.