TY - JOUR
T1 - Optimization of combinations of bactericidal and bacteriostatic treatments to control Listeria monocytogenes on cold-smoked salmon
AU - Kang, Jihun
AU - Stasiewicz, Matthew J.
AU - Murray, Dillon
AU - Boor, Kathryn J.
AU - Wiedmann, Martin
AU - Bergholz, Teresa M.
N1 - Funding Information:
This work was supported by New York Sea Grant R/SHH-16, funded under award NA07OAR4170010 from the National Sea Grant College Program of the U.S. Department of Commerce's National Oceanic and Atmospheric Administration , to the Research Foundation of State University of New York, and by Agriculture and Food Research Initiative grant 2010-65201-20575 from the U.S. Department of Agriculture, National Institute of Food and Agriculture , Food Safety Program. We thank Silin Tang for assistance with the smoked salmon inoculation experiments, and Maureen Gunderson for assistance with media preparation.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2014/6/2
Y1 - 2014/6/2
N2 - Contamination of cold-smoked salmon by Listeria monocytogenes is a major concern for the seafood industry. The objectives of this study were to (i) determine the most effective bactericidal treatment for L. monocytogenes on salmon and (ii) optimize bactericidal and bacteriostatic treatment combinations to identify cost-effective treatments against L. monocytogenes on salmon. L. monocytogenes challenge trials were conducted in brain heart infusion (BHI) and on salmon disks that were supplemented with bactericidal compounds nisin (NIS), lauric arginate (LAE), ε-polylysine (EPL), and chitosan (CHIT). Subsequently, the most effective bactericidal compound was further tested by concurrent application of a blend of organic acid salts containing potassium lactate and sodium diacetate (PLSDA). L. monocytogenes populations were measured at 7°C over 60days, and initial cell density (N0), maximum initial log reduction (Nr), lag phase (λ), maximum growth rate (μmax), and maximum cell density (Nmax) over 60days storage were estimated. Time to recover to initial cell density (Tinitial) was also compared for combinations of bactericidal and bacteriostatic treatments. Varying degrees of antimicrobial effects were observed with bactericidal compounds in BHI. However, when tested on salmon, only NIS significantly decreased initial L. monocytogenes populations by approximately 2logCFU/g, and reduced Nmax by approximately 1.5logCFU/g compared to untreated control (CTRL). Nr achieved by the combined treatment of NIS and PLSDA was approximately 2logCFU/g regardless of the presence of PLSDA, and a dose-dependent increase in Nr was observed with increasing NIS concentrations. PLSDA alone or in combination with 20ppm NIS was most effective at delaying growth of L. monocytogenes. The greatest reduction in Nmax was observed with the combination of 20ppm NIS and PLSDA; Nmax was 3.1logCFU/g lower compared to CTRL. Comparison of Tinitial indicated that PLSDA with NIS can effectively retard growth of L. monocytogenes to its initial level (following initial reduction) and offers a cost benefit over using high concentrations of NIS alone. In summary, the combined application of NIS (for a bactericidal effect) and PLSDA (for a bacteriostatic effect) proved to be an effective treatment option to reduce initial levels as well as minimize subsequent growth of L. monocytogenes throughout the expected shelf-life of cold-smoked salmon.
AB - Contamination of cold-smoked salmon by Listeria monocytogenes is a major concern for the seafood industry. The objectives of this study were to (i) determine the most effective bactericidal treatment for L. monocytogenes on salmon and (ii) optimize bactericidal and bacteriostatic treatment combinations to identify cost-effective treatments against L. monocytogenes on salmon. L. monocytogenes challenge trials were conducted in brain heart infusion (BHI) and on salmon disks that were supplemented with bactericidal compounds nisin (NIS), lauric arginate (LAE), ε-polylysine (EPL), and chitosan (CHIT). Subsequently, the most effective bactericidal compound was further tested by concurrent application of a blend of organic acid salts containing potassium lactate and sodium diacetate (PLSDA). L. monocytogenes populations were measured at 7°C over 60days, and initial cell density (N0), maximum initial log reduction (Nr), lag phase (λ), maximum growth rate (μmax), and maximum cell density (Nmax) over 60days storage were estimated. Time to recover to initial cell density (Tinitial) was also compared for combinations of bactericidal and bacteriostatic treatments. Varying degrees of antimicrobial effects were observed with bactericidal compounds in BHI. However, when tested on salmon, only NIS significantly decreased initial L. monocytogenes populations by approximately 2logCFU/g, and reduced Nmax by approximately 1.5logCFU/g compared to untreated control (CTRL). Nr achieved by the combined treatment of NIS and PLSDA was approximately 2logCFU/g regardless of the presence of PLSDA, and a dose-dependent increase in Nr was observed with increasing NIS concentrations. PLSDA alone or in combination with 20ppm NIS was most effective at delaying growth of L. monocytogenes. The greatest reduction in Nmax was observed with the combination of 20ppm NIS and PLSDA; Nmax was 3.1logCFU/g lower compared to CTRL. Comparison of Tinitial indicated that PLSDA with NIS can effectively retard growth of L. monocytogenes to its initial level (following initial reduction) and offers a cost benefit over using high concentrations of NIS alone. In summary, the combined application of NIS (for a bactericidal effect) and PLSDA (for a bacteriostatic effect) proved to be an effective treatment option to reduce initial levels as well as minimize subsequent growth of L. monocytogenes throughout the expected shelf-life of cold-smoked salmon.
KW - Antimicrobials
KW - Cold-smoked salmon
KW - Growth inhibitors
KW - Listeria monocytogenes
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U2 - 10.1016/j.ijfoodmicro.2014.03.017
DO - 10.1016/j.ijfoodmicro.2014.03.017
M3 - Article
C2 - 24699233
AN - SCOPUS:84897464355
SN - 0168-1605
VL - 179
SP - 1
EP - 9
JO - International Journal of Food Microbiology
JF - International Journal of Food Microbiology
ER -