Modeling growth of Escherichia coli O157:H7 in fresh-cut lettuce treated with neutral electrolyzed water and under modified atmosphere packaging

• E. coli O157:H7 inoculated in fresh-cut lettuce could grow at low temperatures (8 °C).
• Neutral electrolyzed water treatment resulted in less growth than chlorinated water.
• A secondary model described E. coli O157:H7 growth as a function of temperature.

The purpose of this study was to evaluate and model the growth of Escherichia coli O157:H7 in fresh-cut lettuce submitted to a neutral electrolyzed water (NEW) treatment, packaged in passive modified atmosphere and subsequently stored at different temperatures (4, 8, 13, 16 °C) for a maximum of 27 days. Results indicated that E. coli O157:H7 was able to grow at 8, 13, and 16 °C, and declined at 4 °C. However at 8 °C, the lag time lasted 19 days, above the typical shelf-life time for this type of products. A secondary model predicting growth rate as a function of temperature was developed based on a square-root function. A comparison with literature data indicated that the growth predicted by the model for E. coli O157:H7 was again lower than those observed with other disinfection treatments or packaging conditions (chlorinated water, untreated product, NEW, etc.). The specific models here developed might be applied to predict growth in products treated with NEW and to improve existing quantitative risk assessments.