Intense Pulsed Light Treatment for Reducing Escherichia coli and Salmonella on Fresh‐Cut Romaine Lettuce and Its Effects on Product Quality

Foodborne illnesses caused by pathogenic microorganisms have been increasingly linked to the consumption of fresh produce. In recent years, leafy greens, such as fresh‐cut lettuce and packaged salads, have been implicated in outbreaks involving Escherichia coli (E. coli) O157:H7 and Salmonella . Intense pulsed light (IPL) is a nonthermal technology for food surface decontamination. This study assessed IPL for decontaminating fresh‐cut Romaine lettuce and its effects on product quality during 10 days of storage at 5°C. Abaxial side of lettuce pieces (3.5 × 3.5 cm) were inoculated with nalidixic acid‐resistant (100 µg/mL) strains of Escherichia coli (ATCC 8739) and Salmonella Typhimurium (ATCC 14028) and then treated with IPL for 0 to 11.5 s (0 to 8 pulses). Significant maximum reductions of 4.03 and 4.47 log CFU/cm 2 were achieved for E. coli and Salmonella , respectively. While IPL caused significant changes in color ( L * , a * , b * ) and browning index, no significant changes were observed in firmness and chlorophyll content. However, IPL significantly increased electrolyte leakage. Native spoilage microbiota (total mesophilic, yeast and mold, and psychrotrophic counts) increased similarly in IPL‐treated and control samples. The IPL‐treated leaves showed higher total sugar content. Overall, IPL treatment on Romaine lettuce effectively reduced pathogens and has the potential to be used as an effective decontamination method for improving microbial safety and preserving quality attributes. Practical Applications Leafy greens like Romaine lettuce have been contaminated with foodborne pathogens such as, E. coli and Salmonella , resulting in recalls, outbreaks, illnesses, and, in extreme cases, death. Nonthermal treatments are needed to maintain product quality and eliminate pathogens. Intense pulsed light has the potential to be used as a dry treatment method for fresh‐cut lettuce. This technology can be incorporated into the production line during pre‐wash and trimming steps prior to packaging to treat lettuce surface for potential E. coli and Salmonella contamination.