71A-2 |
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S. MIN1, L. J. Harris1, J. H. Han2, and J. M. Krochta1. (1) Dept. of Food Science and Technology, Univ. of California-Davis, 1 Shields Ave., Davis, CA 95616-8598, (2) Dept. of Food Science, Univ. of Manitoba, 250 Ellis Bldg., Winnipeg, MB R3T 2N2, Canada Identification of novel means to control L. monocytogenes is considered important for the ready-to-eat (RTE) seafood and meat industries, because refrigeration and vacuum packaging do not completely prevent the growth of L. monocytogenes in these products. The objectives of this study were to: (1) assess the antimicrobial effect of whey protein isolate (WPI) films incorporating lysozyme (LZ) or lactoperoxidase systems (LPOS) (LZ-WPI or LPOS-WPI films) against L. monocytogenes; (2) evaluate the effects of LZ-WPI and LPOS-WPI coatings on the microbial stability of L. monocytogenes-inoculated cold smoked salmon during storage; and (3) compare tensile and physical properties of plain WPI, LZ-WPI, and LPOS-WPI films. Antimicrobial effects of WPI films were evaluated by observation of inhibition zones on inoculated agar and by conducting a storage study (4 and 10 °C, 35 days) using inoculated smoked salmon as a model food system. Elastic modulus (EM), tensile strength (TS), percent elongation (%E), oxygen permeability (OP), and Hunter L, a, and b of WPI films, with and without LZ or LPOS, were also compared. WPI films incorporating 204 mg/g film of LZ or 29 mg/g film of LPOS (dry basis) inhibited L. monocytogenes at a concentration of 4 log CFU/cm2. WPI coatings prepared with LZ at 25 mg/g or LPOS at 0.7% (w/w) in a coating solution initially inactivated more than 2.4 and 3.0 log CFU/g of L. monocytogenes inoculated in smoked salmon, respectively. Both LZ-WPI and LPOS-WPI coatings inhibited the growth of L. monocytogenes at 4 and at 10 °C. Growth of endogenous aerobic microorganisms was also inhibited. Incorporation of LZ (204 mg/g) increased EM and lowered %E and OP. Incorporation of LPOS (40 mg/g film) did not change film properties. Both LZ-WPI and LPOS-WPI films and coatings have potential for inhibiting post-processing contamination of L. monocytogenes on RTE fish and other RTE products.
Session 71A, Dairy Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |