Efficacy of Neutral pH Electrolyzed Water in Reducing Escherichia coli O157:H7 and Salmonella Typhimurium DT 104 on Fresh Produce Items using an Automated Washer at Simulated Food Service Conditions

Abstract

The objective of this study was to determine the efficacy of neutral pH electrolyzed (NEO) water (155 mg/L free chlorine, pH 7.5) in reducing Escherichia coli O157:H7 and Salmonella Typhimurium DT 104 on romaine lettuce, iceberg lettuce, and tomatoes washed in an automated produce washer for different times and washing speeds. Tomatoes and lettuce leaves were spot inoculated with 100 μL of a 5 strain cocktail mixture of either pathogen and washed with 10 or 8 L of NEO water, respectively. Washing lettuce for 30 min at 65 rpm led to the greatest reductions, with 4.2 and 5.9 log CFU/g reductions achieved for E. coli O157:H7 and S. Typhimurium respectively on romaine, whereas iceberg lettuce reductions were 3.2 and 4.6 log CFU/g for E. coli O157:H7 and S. Typhimurium respectively. Washing tomatoes for 10 min at 65 rpm achieved reductions greater than 8 and 6 log CFU/tomato on S. Typhimurium and E. coli O157:H7 respectively. All pathogens were completely inactivated in NEO water wash solutions. No detrimental effects on the visual quality of the produce studied were observed under all treatment conditions. Results show the adoption of this washing procedure in food service operations could be useful in ensuring produce safety.

Efficacy of Slightly Acidic Electrolyzed Water and UV‐Ozonated Water Combination for Inactivating Escherichia Coli O157:H7 on Romaine and Iceberg Lettuce during Spray Washing Process

“…Hence, a 5 log reductions of E. coli O157:H7 using UV‐ozonated water combination was observed for both iceberg lettuce and romaine lettuce. Similar results were reported by Afari and others (). They used neutral pH EO water (NEO, 155 mg/L free chlorine, pH 7.5) in an automated produce washer at 65 rpm for 30 min and achieved 4.2 and 3.2 log CFU/g reductions for romaine and iceberg lettuce, respectively.…”

“…For iceberg lettuce, a 10 min treatment did not cause additional inactivation of the bacteria, although a 15 min treatment led to an additional reduction of 0.8 log CFU/g of E. coli O157:H7. A similar result was reported by Afari and other's (), which stated that the reduction of E. coli O157:H7 on romaine lettuce was higher than on iceberg lettuce by 1 log when both samples were treated with SAEW.…”

Efficacy of Peracetic Acid in Inactivating Foodborne Pathogens on Fresh Produce Surface

“…Inoculation and application of sanitizer treatment procedure for romaine lettuce was adapted from one of our previous publications (Afari and others ). Lettuce heads were trimmed to remove the lower part with root.…”

“…Lettuce samples were washed using an automated salad washer (Afari and others ) with a 2‐step washing protocol. Four hundred grams of lettuce were washed with 8 L chilled (4 °C) sanitizer solutions (1:20) in the washer with agitation at 65 rpm for 5 min.…”

“…Inoculation and application of sanitizer treatment procedure for lemons and tomatoes was also adapted from one of our previous publications (Afari and others ). Lemons and tomatoes were visually inspected and 10 uniform‐sized lemons or tomatoes (1000 ± 100 g) with no visible damage were selected for each sanitizer treatment.…”