INHIBITION OF LISTERIA-MONOCYTOGENES AND ESCHERICHIA-COLI O157-H7 ON BEEF BY APPLICATION OF ORGANIC-ACIDS

Lean beef surfaces were inoculated with Escherichia coli O157:H7 and L isteria monocytogenes and then sanitized with fumaric, acetic, or lact ic acid alone and in combined solutions of those acids at 55 degrees C for 5 s. The initial inoculum level was 8.62 log CFU/cm(2) and 5.13 l og CFU/cm(2) for L. monocytogenes and E. coli O157:H7, respectively. F umaric acid at a concentration of 1% was the most effective acid in re ducing the populations of L. monocytogenes by up to 1 log unit and E. coli O157:H7 by up to 1.3 log units when compared with acetic or lacti c acids. The rank order of acids tested against the growth of L. monoc ytogenes and E. coli O157:H7 was fumaric acid followed by lactic and a cetic acids. Fumaric acid at concentrations of 1.0% and 1.5% was more effective than any of the combined solutions of acids.