89D-10

S. GAYSINSKY¹, P. M. Davidson², J. R. Mount², B. Bruce³, and J. Weiss⁴. (1) Food Science, Univ. of Massachusetts, 100 Holword way, Chenoweth Lab Box 31410, Amherst, MA 01003, (2) Dept. of Food Science & Technology, Univ. of Tennessee, 2509 River Dr., 201 Mcleod Food Tech Bldg., Knoxville, TN 37996-4539, (3) Dept. of Biochemistry and Cellular and Molecular Biology, Univ. of Tennessee, Knoxville, TN 37996, (4) Dept. of Food Science, Univ. of Massachusetts, Amherst, 234 Chenoweth Lab., Box 31410, Amherst, MA 01003-1410

Listeria monocytogenes and Escherichia coli O157:H7 are two major foodborne pathogens encountered in milk and dairy products. The objective of this study was to determine the antimicrobial activity of eugenol encapsulated in surfactant-based nanoparticles in UHT pasteurized milk containing different percentages of butterfat (0 and 2%). Antimicrobial solutions were prepared by mixing a 5 wt% aqueous surfactant solution (Surfynol 485W) with 0.5 wt% eugenol to initiate solubilization. Two strains of each microorganisms, that had previously been shown to be the least and most resistant to the antimicrobial system in microbiological media, were used to inoculated sterile milk (104 CFU/ml). Controls consisted of pure eugenol (0.5%) and eugenol-free surfactant solutions (5% surfactant). Strains were plated at 0, 1, 3, 6, 12, and 24 hr to determine the antimicrobial efficacy of the antimicrobial system. In 2% fat milk, eugenol-Surfynol combinations reduced both strains of E. coli O157:H7 to less than detectable levels in less than 1 hr and increased the lag phase of both strains of L. monocytogenes. Pure eugenol was slightly more or equally inhibitory against L. monocytogenes and E. coli O157:H7. Fat content affected the antimicrobial efficacy of the nanoparticles. Nanoparticles completely prevented growth of L. monocytogenes for up to 48 hr in skim milk. As in 2% fat milk, both strains of E. coli O157:H7 to less than detectable levels in less than 1 hr. Results suggest that food composition, especially fat level, may affect the efficiency of targeting of foodborne pathogens by nanoparticles. This could decrease their antimicrobial activity, possibly due to partitioning into available lipid phases. Nevertheless, the eugenol-Surfynol nanoparticles were effective at inhibiting both microorganisms and have the added advantage of being a water soluble antimicrobial system in contrast to the fat soluble pure eugenol.

Session 89D, Food Microbiology: Antimicrobial effects on foodborne microorganisms
2:00 PM - 5:30 PM, Tuesday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana