Inactivation of Salmonella and Escherichia coli O157:H7 on lettuce and poultry skin by combinations of levulinic acid and sodium dodecyl sulfate.

Abstract

Four organic acids (lactic acid, acetic acid, caprylic acid, and levulinic acid) and sodium dodecyl sulfate (SDS) were evaluated individually or in combination for their ability to inactivate Salmonella and Escherichia coli O157:H7. Results from pure culture assays in water with the treatment chemical revealed that 0.5% organic acid and 0.05 to 1% SDS, when used individually, reduced pathogen cell numbers by < or = 2 log CFU/ml within 20 min at 21 degrees C. The combination of any of these organic acids at 0.5% with 0.05% SDS resulted in > 7 log CFU/ml inactivation of Salmonella and E. coli O157:H7 within 10 s at 21 degrees C. A combination of levulinic acid and SDS was evaluated at different concentrations for pathogen reduction on lettuce at 21 degrees C, on poultry (wings and skin) at 8 degrees C, and in water containing chicken feces or feathers at 21 degrees C. Results revealed that treatment of lettuce with a combination of 3% levulinic acid plus 1% SDS for < 20 s reduced both Salmonella and E. coli O157:H7 populations by > 6.7 log CFU/g on lettuce. Salmonella and aerobic bacterial populations on chicken wings were reduced by > 5 log CFU/g by treatment with 3% levulinic acid plus 2% SDS for 1 min. Treating water heavily contaminated with chicken feces with 3% levulinic acid plus 2% SDS reduced Salmonella populations by > 7 log CFU/ml within 20 s. The use of levulinic acid plus SDS as a wash solution may have practical application for killing foodborne enteric pathogens on fresh produce and uncooked poultry.