Survival of Escherichia coli O157, Salmonella, and Listeria monocytogenes in Ethanol and Juice Mixtures at Ambient Temperature

Some bars and restaurants have begun displaying alcoholic fruit and vegetable cocktail mixes at ambient temperature. Operators often believe that ethanol makes this practice safe, and conversely, some regulators question the safety. It has been reported that ethanol may inhibit the growth of some bacteria at concentrations starting at 8–10% and may be biocidal at concentrations ≥ 30%. In this study, Escherichia coli O157, Salmonella, and Listeria monocytogenes did not grow in banana puree, pear puree, orange juice, and apple juice cocktail mixtures prepared with ethanol concentrations from 10 to 50% at 25°C. Inoculated pathogens were not detected in juice plus ethanol at 40 or 50% after 48 h. Juices with ethanol concentrations of 10–30% exhibited different log reductions over time for each of the pathogens introduced. This study has implications for how regulators assess the risk of ethanol juice mixtures held at ambient temperature under the U.S. Food and Drug Administration (FDA) Food Code. Operators that desire to display ethanol and fruit juice mixtures at room temperature need to ensure a pH < 4.2 or a combination of pH and water activity values based on Table B of the FDA Food Code, or they must keep the product under refrigeration at a temperature ≤ 41°F.