89D-5 |
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I. GEORNARAS and J. N. Sofos. Dept. of Animal Sciences, Colorado State Univ., 1171 Campus Delivery, Fort Collins, CO 80523-1171 e-Polylysine is a homopolymer of L-lysine with a wide antimicrobial spectrum. To date, there have been no published investigations on its effectiveness against foodborne bacterial pathogens, and how it compares in antimicrobial activity with other commonly used antimicrobial agents. This study investigated the antimicrobial effect of e-polylysine, as compared to known preservatives and organic acids, against Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes, in culture broth. The antimicrobials and concentrations tested included e-polylysine (25-500 ppm), sodium diacetate (0.25%), sodium lactate (3.0%), lactic acid (0.1%) and acetic acid (0.1%), alone, as well as in combination with e-polylysine; all treatments were evaluated in tryptic soy broth supplemented with 0.6% yeast extract. Treatments were inoculated (approximately 2 log CFU/ml) with five-strain (E. coli O157:H7, Salmonella Typhimurium) or 10-strain (L. monocytogenes) mixtures of the pathogens. The survival/growth of the inoculated bacteria were periodically monitored by spiral plating during storage at 4oC (30 days) and 24oC (48 h). Bactericidal effects were obtained for E. coli O157:H7 and Salmonella Typhimurium in the presence of 25-500 ppm e-polylysine at 4oC. L. monocytogenes growth was inhibited and bactericidal effects were also observed in the presence of e-polylysine tested alone as well as in combination with sodium diacetate, sodium lactate, lactic acid and acetic acid. All three pathogens were inhibited by e-polylysine at 24oC; however, L. monocytogenes was the most sensitive and Salmonella Typhimurium the most resistant. The antimicrobial activity of e-polylysine against E. coli O157:H7 and Salmonella Typhimurium was enhanced when tested in combination with sodium diacetate and acetic acid. Combination treatments with sodium lactate resulted in loss of e-polylysine activity for all three pathogens. Under the conditions of the broth study, e-polylysine was effective against the three foodborne pathogens tested; however, additional research is needed to explore its potential antimicrobial effects in food systems.
Session 89D, Food Microbiology: Antimicrobial effects on foodborne microorganisms
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |