P3-106 Validation of Washing Treatments to Reduce Pathogens in Fresh Produce

Wednesday, July 31, 2013
Exhibit Hall (Charlotte Convention Center)
Keyla Lopez, Kansas State University, Manhattan, KS
Kelly Getty, Kansas State University, Manhattan, KS
Introduction: Many fresh produce outbreaks are the result of Salmonella and Escherichia coli O157:H7 contamination due to growing conditions or human handling. 

Purpose: The purpose of this study was to determine the efficacy of a commercial wash solution for reducing pathogens in green leaf lettuce and tomatoes. 

Methods: Lettuce (25 ± 0.3 g) and tomato (whole tomato) samples were inoculated with E. coli O157:H7 (~7.8 log CFU/ml) and Salmonella spp. (~9.39 log CFU/ml) cocktail inoculums, respectively, and then dried for 1 h.  Inoculated samples were washed separately with commercial wash solution (contains citric acid and grapefruit oil) or tap water (control) for three contact times (30, 60, and 120 s). Lettuce (25 ± 0.3 g) and tomato (core of 11.34 cm2) samples were diluted and stomached for 1 min and then 0.1 ml was plated onto CT-SMAC and XLD agar plates for E. coli O157:H7 and Salmonella recovery. Experiment consisted of three replications and two samples per treatment (n = 6).

Results: Recovery of E. coli O157:H7 populations on leaf lettuce were different (P < 0.05) between commercial wash and tap water. For lettuce samples, E. coli O157:H7 reductions for 30, 60, and 120 s of commercial wash treatment were 3.12, 3.22, and 3.30 log CFU/g, respectively while, tap water resulted in ≥ 2.2 log CFU/g reductions. There were no differences (P > 0.05) between commercial wash and tap water in Salmonella populations recovered from tomatoes samples. For commercial wash treatments, Salmonella reductions on tomatoes were 2.13 log CFU/cm2 for all contact times whereas, tap water resulted in ≤ 2.0 log CFU/cm2 reductions.

Significance: Commercial wash solution reduced E. coli O157:H7 populations by > 3.0 logs on leaf lettuce and Salmonella populations by > 2.0 logs on tomatoes for all contact times. The commercial wash solution is applicable for food service and home-use and would reduce risk of pathogens on produce.