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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Characterization and Interventions for Foodborne Pathogens » Research » Publications at this Location » Publication #411234
Research Project: Validation and Commercialization of Innovative Processing Technologies

Location: Characterization and Interventions for Foodborne Pathogens

Title: Pulsed light and sanitizer wash combination enhances inactivation efficacy against Escherichia coli O157:H7 in Romaine lettuce

Author
item Mukhopadhyay, Sudarsan
item Ukuku, Dike
item Olanya, Modesto
item Niemira, Brendan
item Jin, Zhonglin
item Fan, Xuetong

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/18/2024
Publication Date: 7/14/2024
Citation: Mukhopadhyay, S., Ukuku, D.O., Olanya, O.M., Niemira, B.A., Jin, Z.T., Fan, X. 2024. Pulsed light and sanitizer wash combination enhances inactivation efficacy against Escherichia coli O157:H7 in Romaine lettuce. Meeting Abstract. p. 306.

Interpretive Summary: N/A

Technical Abstract: Romaine lettuce has been frequently implicated in outbreaks of foodborne illness. The produce industry uses chlorine-based sanitizer wash which has only limited efficacy. Safe and effective new methods are needed. The purpose of this study was to investigate the efficacy of integrated treatment of Pulsed light (PL) and sanitizer wash (SW) against E. coli O157:H7 on Romaine lettuce, as an effective alternative strategy to current chlorine wash. Romaine lettuce was spot inoculated with a bacterial cocktail containing three outbreaks strains of Escherichia coli O157:H7 to a level of about 6 log CFU/g. Two different combination treatment strategies were explored, namely, PL followed by SW (PL-SW) and SW followed by PL (SW-PL). Briefly, Romaine lettuce was washed with 250 mL sanitizer for 2 min before and after PL treatment for 10 s (10.5 Joule per square cm). Homogenates of lettuce sample was prepared by stomaching in peptone water. Pathogen populations were quantified by plating 100 µL of homogenate dilutions on SMAC selective medium (37 degree C). When populations were below detection limit, pathogen absence in the sample was confirmed by enrichment methods. Experiments were conducted in triplicate and data were analyzed with ANOVA to assess significance of treatment effects by statistical analysis system (SAS Institute, Cary, NC). Statistically significant (p<0.05) increases in pathogen inactivation was achieved by combination treatments of PL and SW compared to individual treatments. PL (10 s) and SW (2 min) treatments individually inactivated 2.3±0.32 and 2.2±0.25 logs of E. coli, respectively on Romaine lettuce. Both combination treatments (PL-SW and SW-PL) resulted in synergistic inactivation as E. coli cells were not detectable after combination treatments, indicating >5 log pathogen reductions. These results suggest that PL and SW combination is an efficacious treatment strategy which can ensure the microbial safety of Romaine lettuce.