Growth and inhibition by acids of five species of pathogenic bacteria inoculated in salad vegetables

The growth of Yersinia, Listeria monocytogenes, Escherichia coli O157, and Staphylococcus aureus in salad vegetables stored at 5 degrees C, 10 degrees C, and 25 degrees C, and the initial reduction of the bacterial population s by treatment of the vegetables with organic acids were examined. The mult iplication of Yersinia enterocolitica was observed in cabbage and radishes held at 5 degrees C for 4 days, at 10 degrees C for 2 to 3 days, and at 25 degrees C for 1 day. That of Yersinia pseudotuberculosis was observed in ra dishes at 5 degrees C for 3 days, at 10% for 3 days and at 25 degrees C for 1 day. That of L. monocytogenes was observed in radishes at 10 degrees C f or 3 days, and in cabbage and carrots stored at 25 degrees C for 1 day. Tha t of E. coli O157 was observed in cucumbers held. at 10 degrees C for 3 day s and in all five kinds of vegetables held at 25 degrees C for 1 day. Reduc tion of L, monocytogenes, E. coli O157, and S. aureus by log 2 cycles or mo re was observed within 2 days after treatment with fumaric acid. Following treatment with acetic acid and lactic acid, the reduction of the initial po pulation of these bacteria was about log 1 cycle.