SUPERIOR EFFICACY OF DISINFECTANT WASH SOLUTION OF CITRIC ACID COMBINED WITH OTHER GENERALLY RECOGNIZED AS SAFE COMPOUNDS AGAINST FOODBORNE PATHOGEN ESCHERICHIA COLI O157:H7

Abstract

Escherichia coli O157:H7 is the etiological agent of severe intestinal infection in humans causing foodborne illness through consumption of contaminated raw food. The study tested bactericidal activity against E. coli O157:H7 of citric acid solution alone or in combination with three other generally recognized as safe (GRAS) compounds, four common household wash solutions and a commercial wash solution. Citric acid solution (0.112 mg/ml) was more effective, achieving 1, 6 and 12 log10 reduction in 3, 19 and 38 minutes, respectively compared to a commercial wash solution, with 1 log10 reduction in 15 minutes. Bactericidal efficacy of the citric acid solution was highly improved when supplemented with GRAS compounds, namely, ethylenediaminetetraacetic acid (0.01 g/ml), L-ascorbic acid (0.013 g/ml) and sodium lauryl ether sulfate (0.031 g/ml), at 4°C and 25°C, with >3 log10 reduction in 5 minutes; the efficacy was slightly reduced at 40°C. However, household wash solutions (distilled water, 0.04% (v/v) hydrogen peroxide, 20.0% (w/v) sodium chloride, and 2.50% (v/v) vinegar) were markedly less effective, with 1 log10 reduction in 259-1,550 minutes. These findings indicate a solution of citric acid together with other GRAS compounds have the potential as a superior disinfectant or preservative in inhibiting E. coli O157:H7 growth compared to common household and commercial disinfectant wash solutions. This study is critically relevant to ongoing strategies in diminishing the risk of coliform contamination in products.