Combined effect of aerosolized malic acid and UV‐C for the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on fresh‐cut lettuce

Abstract

This study was conducted to investigate the effects of aerosolized malic acid and ultraviolet light (UV‐C) for inhibiting the growth of foodborne pathogens, Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes, on fresh‐cut lettuce. The antimicrobial effects of aerosolized 2% malic acid and UV‐C, alone or in combination, were tested. Ten grams of lettuce were inoculated with three strains of each pathogens and treated with aerosolized malic acid for 20 min and UV‐C for 30 min. After each treatment, lettuce was stored at 5 °C for 15 days. Sequential treatment (aerosolized malic acid after UV‐C) was the most effective for reducing E. coli O157:H7, S. Typhimurium, and L. monocytogenes and resulted in reduction of 2.89, 1.38, and 2.95 log10 CFU/g after treatment and 3.15, 3.00, and 4.58 log10 CFU/g after 15 days, respectively. These results suggested that combined treatment with aerosolized malic acid after UV‐C can be a useful intervention method for improving the microbial safety of fresh‐cut produce. Practical applications The experiment suggested new method on the inactivation of foodborne pathogens on lettuce. Treatment with aerosolized 2% malic acid after UV‐C was the most effective method to inhibit the growth of foodborne pathogens in this study. This method will be helpful for fresh‐cut lettuce producers to manage the safety and quality of lettuce.

Effects of Combined Aerosolization with Ultraviolet C Light-Emitting Diode on Enterohemorrhagic Escherichia coli and Staphylococcus aureus Attached to Soft Fresh Produce

“…and E. coli populations by 1.8-1.85 log CFU g −1 and 1.1-1.2 log CFU g −1 , respectively. Combined treatment of aerosolization with 2% malic acid for 20 min and UVC irradiation (254 nm) for 30 min was also more effective in reducing pathogen populations than a single treatment [31]. After combined treatment, populations of E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes in fresh-cut lettuce were reduced 1.65, 1.01, and 1.06 log CFU g −1 , respectively.…”

“…An inactivation effect of UVC LED treatment on E. coli O157:H7, S. Typhimurium, and L. monocytogenes inoculated onto sliced deli meat, spinach surface [30] and sliced cheese [32] were reported. However, the combined effect of the aerosolization of malic acid and UVC on the inactivation of pathogens in fresh-cut lettuce was only reported by Seong et al [31]. As far as we know, the combined effect of aerosolization using SAEW and UVC LED for soft fresh produce has not been reported yet.…”

“…In this work, no significant difference in EHEC or S. aureus reduction was observed between dipping in 100 ppm NaClO for 5 min and the combined treatment of 100 SAEW and UVC LED treatment (data not shown). According to previous studies [29,31,38,39], combined treatment of washing methods with UVC LED or UVC LPM lamps could result in a more effective reduction in foodborne pathogens in fresh produce. Jiang et al [29] revealed that a combined treatment of 60 ppm SAEW for 5 min with UV LED (240 µWcm −2 at 6 cm distance) for coriander reduced Salmonella spp.…”

“…On the other hand, populations of S. aureus in strawberries were decreased after 7 days of storage in all treatment conditions (Figure 3b). The combined treatment of 100 Several previous studies have reported different behaviors of foodborne pathogens in fresh produce during storage after a reduction treatment [17,28,29,31,[40][41][42]. Growths of E. coli and S. aureus in carrots and celery have been observed after treatment with a combination of 30 ppm SAEW, ultrasound, and UVC LED when they are stored at 15 °C for 7 days [28].…”

“…Several studies have also investigated the effects of aerosolization, UV LED, or UVC LED on reducing bacteria populations in food [17,19,[29][30][31][32]. Jiang et al [17] suggested an in-package aerosolization technology to improve the microbial safety of cherry tomatoes against Salmonella spp.…”