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Haiqiang Chen - One of the best experts on this subject based on the ideXlab platform.
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effectiveness of chitosan coated plastic films incorporating antimicrobials in inhibition of listeria monocytogenes on cold Smoked Salmon
International Journal of Food Microbiology, 2008Co-Authors: Mu Ye, Hudaa Neetoo, Haiqiang ChenAbstract:Abstract The objective of this study was to evaluate the efficacy of chitosan-coated plastic films incorporating five Generally Recognized as Safe (GRAS) antimicrobials (nisin, sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS) and sodium benzoate (SB)) against Listeria monocytogenes on cold-Smoked Salmon. Salmon samples were surface-inoculated with a five-strain cocktail of L. monocytogenes and packaged in chitosan-coated plastic films containing 500 IU/cm2 of nisin, 9 mg/cm2 of SL, 0.5 mg/cm2 of SD, 0.6 mg/cm2 of PS, or 0.2 mg/cm2 of SB, and stored at room temperature (ca. 20 °C) for 10 days. The film incorporating SL was the most effective, completely inhibiting the growth of L. monocytogenes during 10 days of storage. L. monocytogenes in samples packaged in the other four antimicrobial films grew, but the increase in counts was lower than the control. The antilisterial efficacy of films containing lower concentrations of SL (2.3 mg/cm2 and 4.5 mg/cm2) and binary combinations SL, PS, SD, SB and nisin were subsequently evaluated. Among all the treatments, chitosan-coated plastic films with 4.5 mg/cm2 SL, 4.5 mg/cm2 SL–0.6 mg/cm2 PS and 2.3 mg/cm2 SL–500 IU/cm2 nisin were the most effective. These three most effective antimicrobial films were then tested at refrigerated temperature. They completely inhibited the growth of L. monocytogenes on Smoked Salmon for at least 6 weeks. Chitosan-coated plastic films containing 4.5 mg/cm2 SL can potentially assist the Smoked-Salmon processing industry in their efforts to control L. monocytogenes.
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potential antimicrobials to control listeria monocytogenes in vacuum packaged cold Smoked Salmon pâte and fillets
International Journal of Food Microbiology, 2008Co-Authors: Hudaa Neetoo, Mu Ye, Haiqiang ChenAbstract:Abstract In the wake of recent outbreaks associated with Listeria monocytogenes in ready-to-eat foods and an increasing desire for minimally processed foods, there has been a burgeoning interest in the use of natural antimicrobials by the food industry to control this pathogen. The minimum inhibitory concentrations (MICs) of nisin and salts of organic acids (sodium lactate (SL), sodium diacetate (SD), sodium benzoate (SB), and potassium sorbate (PS)) against twelve strains of L. monocytogenes in a TSBYE broth medium at 35 °C were determined. The MICs were strain-dependent and fell in the range of 0.00048–0.00190% for nisin, 4.60–5.60% for SL, 0.11–0.22% for SD, 0.25–0.50% for SB and 0.38–0.75% for PS, respectively. The two most antimicrobial-resistant strains were used as a cocktail in the following experiments to represent a worst case scenario. The five antimicrobials alone and in binary combinations were screened for their efficacy against the two-strain cocktail in TSBYE at sub-MIC and sub-legal levels at 35 °C. Seven effective antimicrobial treatments were then selected and evaluated for their long-term antilisterial effectiveness in cold-Smoked Salmon pâte and fillets during refrigerated storage (4 °C) of 3 and 6 weeks, respectively. The two most effective antimicrobial formulations for Smoked Salmon pâte, 0.25% SD and 2.4% SL/0.125% SD, were able to inhibit the growth of L. monocytogenes during the 3 weeks of storage. Surface application of 2.4% SL/0.125% SD was the most effective treatment for Smoked Salmon fillets which inhibited the growth of L. monocytogenes for 4 weeks. These antimicrobial treatments could be used by the Smoked Salmon industry in the U.S. and Europe in their efforts to control L. monocytogenes as they are effective against even the most antimicrobial-resistant strains tested in this study.
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use of nisin coated plastic films to control listeria monocytogenes on vacuum packaged cold Smoked Salmon
International Journal of Food Microbiology, 2008Co-Authors: Hudaa Neetoo, Mu Ye, Haiqiang Chen, Rolf D Joerger, D T Hicks, Dallas G HooverAbstract:Abstract Cold-Smoked (Salmo salar) Salmon samples were surface-inoculated with a cocktail of three nisin-resistant strains of L. monocytogenes (PSU1, PSU2 and PSU21) to a level of approximately 5 × 102 or 5 × 105 CFU/cm2 of Salmon surface. The inoculated Smoked Salmon samples were vacuum-packaged with control film (no nisin) or nisin-coated plastic films and stored at either 4 or 10 °C. When the inoculated Smoked Salmon samples were packaged with film coated with 2000 IU/cm2 of nisin, a reduction of 3.9 log CFU/cm2 (compared with control) was achieved at either temperature for samples inoculated with 5 × 102 CFU/cm2 of L. monocytogenes after 56 (4 °C) and 49 (10 °C) days of storage while reductions of 2.4 and 0.7 log CFU/cm2 were achieved for samples inoculated with a high level of L. monocytogenes (5 × 105 CFU/cm2) after 58 (4 °C) and 43 (10 °C) days, respectively. For samples packaged in film coated with 500 IU/cm2 of nisin, reductions of 0.5 and 1.7 log CFU/cm2 were achieved for samples inoculated with a low level of L. monocytogenes (5 × 102 CFU/cm2) after 56 (4 °C) and 49 (10 °C) days of storage while reductions of 1.8 and 0.8 log CFU/cm2 were achieved for samples inoculated with high level of L. monocytogenes after 58(4 °C) and 43 (10 °C) days, respectively. In addition, nisin inhibited the proliferation of background microbiota on Smoked Salmon in a concentration-dependent manner at both storage temperatures although the bacteriostatic effect was more pronounced at refrigeration temperature. This work highlights the potential for incorporating nisin into plastic films for enhancing the microbial safety of Smoked Salmon as well as controlling its microbial spoilage.
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Effectiveness of chitosan-coated plastic films incorporating antimicrobials in inhibition of Listeria monocytogenes on cold-Smoked Salmon
International Journal of Food Microbiology, 2008Co-Authors: Mu Ye, Hudaa Neetoo, Haiqiang ChenAbstract:The objective of this study was to evaluate the efficacy of chitosan-coated plastic films incorporating five Generally Recognized as Safe (GRAS) antimicrobials (nisin, sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS) and sodium benzoate (SB)) against Listeria monocytogenes on cold-Smoked Salmon. Salmon samples were surface-inoculated with a five-strain cocktail of L. monocytogenes and packaged in chitosan-coated plastic films containing 500 IU/cm2of nisin, 9 mg/cm2of SL, 0.5 mg/cm2of SD, 0.6 mg/cm2of PS, or 0.2 mg/cm2of SB, and stored at room temperature (ca. 20 °C) for 10 days. The film incorporating SL was the most effective, completely inhibiting the growth of L. monocytogenes during 10 days of storage. L. monocytogenes in samples packaged in the other four antimicrobial films grew, but the increase in counts was lower than the control. The antilisterial efficacy of films containing lower concentrations of SL (2.3 mg/cm2and 4.5 mg/cm2) and binary combinations SL, PS, SD, SB and nisin were subsequently evaluated. Among all the treatments, chitosan-coated plastic films with 4.5 mg/cm2SL, 4.5 mg/cm2SL-0.6 mg/cm2PS and 2.3 mg/cm2SL-500 IU/cm2nisin were the most effective. These three most effective antimicrobial films were then tested at refrigerated temperature. They completely inhibited the growth of L. monocytogenes on Smoked Salmon for at least 6 weeks. Chitosan-coated plastic films containing 4.5 mg/cm2SL can potentially assist the Smoked-Salmon processing industry in their efforts to control L. monocytogenes. © 2008 Elsevier B.V. All rights reserved.
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Use of nisin-coated plastic films to control Listeria monocytogenes on vacuum-packaged cold-Smoked Salmon.
International journal of food microbiology, 2007Co-Authors: Hudaa Neetoo, Mu Ye, Haiqiang Chen, Rolf D Joerger, D T Hicks, Dallas G HooverAbstract:Cold-Smoked (Salmo salar) Salmon samples were surface-inoculated with a cocktail of three nisin-resistant strains of L. monocytogenes (PSU1, PSU2 and PSU21) to a level of approximately 5 x 10(2) or 5 x 10(5) CFU/cm2 of Salmon surface. The inoculated Smoked Salmon samples were vacuum-packaged with control film (no nisin) or nisin-coated plastic films and stored at either 4 or 10 degrees C. When the inoculated Smoked Salmon samples were packaged with film coated with 2000 IU/cm2 of nisin, a reduction of 3.9 log CFU/cm2 (compared with control) was achieved at either temperature for samples inoculated with 5 x 10(2) CFU/cm(2 of L. monocytogenes after 56 (4 degrees C) and 49 (10 degrees C) days of storage while reductions of 2.4 and 0.7 log CFU/cm2 were achieved for samples inoculated with a high level of L. monocytogenes (5 x 10(5) CFU/cm2) after 58 (4 degrees C) and 43 (10 degrees C) days, respectively. For samples packaged in film coated with 500 IU/cm2 of nisin, reductions of 0.5 and 1.7 log CFU/cm2 were achieved for samples inoculated with a low level of L. monocytogenes (5 x 10(2) CFU/cm2) after 56 (4 degrees C) and 49 (10 degrees C) days of storage while reductions of 1.8 and 0.8 log CFU/cm2 were achieved for samples inoculated with high level of L. monocytogenes after 58(4 degrees C) and 43 (10 degrees C) days, respectively. In addition, nisin inhibited the proliferation of background microbiota on Smoked Salmon in a concentration-dependent manner at both storage temperatures although the bacteriostatic effect was more pronounced at refrigeration temperature. This work highlights the potential for incorporating nisin into plastic films for enhancing the microbial safety of Smoked Salmon as well as controlling its microbial spoilage.
Hans Henrik Huss - One of the best experts on this subject based on the ideXlab platform.
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significance of volatile compounds produced by spoilage bacteria in vacuum packed cold Smoked Salmon salmo salar analyzed by gc ms and multivariate regression
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Lasse Vigel Jorgensen, Hans Henrik Huss, Paw DalgaardAbstract:Changes were studied in the concentration of 38 volatile compounds during chilled storage at 5 °C of six lots of commercially produced vacuum-packed cold-Smoked Salmon and sterile cold-Smoked Salmon. The majority of volatile compounds produced during spoilage of cold-Smoked Salmon were alcohols, which were produced by microbial activity. Partial least-squares regression of volatile compounds and sensory results allowed for a multiple compound quality index to be developed. This index was based on volatile bacterial metabolites, 1-propanol and 2-butanone, and 2-furancarboxaldehyde produced by autolytic activity. Only a few of the volatile compounds produced during spoilage of cold-Smoked Salmon had an aroma value high enough to indicate contribution to the spoilage off-flavor of cold-Smoked Salmon. These were trimethylamine, 3-methylbutanal, 2-methyl-1-butanol, 3-methyl-1-butanol, 1-penten-3-ol, and 1-propanol. The potency and importance of these compounds was confirmed by gas chromatography−olfactometry. ...
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the effect of biogenic amine production by single bacterial cultures and metabiosis on cold Smoked Salmon
Journal of Applied Microbiology, 2000Co-Authors: Lasse Vigel Jorgensen, Hans Henrik Huss, Paw DalgaardAbstract:Aim: Biogenic amines are important indicators of spoilage in vacuum-packed cold-Smoked Salmon. It is the aim of this study to identify bacteria responsible for biogenic amine production in cold-Smoked Salmon. Methods and Results: The present study identified spoilage microflora from cold-Smoked Salmon and determined biogenic amine production of single and co-cultures growing in cold-Smoked Salmon. Photobacterium phosphoreum was the only species that produced histamine when inoculated on sterile cold-Smoked Salmon. Production of putrescine was enhanced 10–15 times when cultures of Serratia liquefaciens or Hafnia alvei were grown with Carnobacterium divergens or Lactobacillus sakei subsp. carnosus. This phenomenon was explained by interspecies microbial metabolism of arginine, i.e., metabiosis. Conclusions: The amounts of biogenic amines produced by single and co-cultures corresponded to those observed during spoilage of naturally-contaminated cold-Smoked Salmon. Photobacterium phosphoreum and Lact. curvatus were identified as the specific spoilage organisms in cold-Smoked Salmon. Significance and Impact of the Study: Determination of the specific spoilage organism is needed before a model can be developed for shelf-life predictions of cold-Smoked Salmon.
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growth control of listeria monocytogenes on cold Smoked Salmon using a competitive lactic acid bacteria flora
Journal of Food Protection, 1999Co-Authors: Lilian Nilsson, Lone Gram, Hans Henrik HussAbstract:A Lactobacillus sake strain LKE5 and four strains of Carnobacterium piscicola were evaluated as biopreservation cultures to control the growth of Listeria monocytogenes on vacuum-packed, cold-Smoked Salmon stored at 5°C. All five strains were antilisterial as live cultures in an agar diffusion assay. Cell-free supernatants of two strains of C. piscicola and L sake LKE5 were also antilisterial because of the production of bacteriocins. The presence of high cell numbers of strains of C. piscicola had no influence on the sensory quality of cold-Smoked Salmon stored at 5°C, but L sake LKE5 caused strong sulfurous off-flavors and was rejected as a culture for biopreservation of cold-Smoked Salmon. A bacteriocin-producing strain of C. piscicola (A9b) initially caused a 7-day lag phase of L. monocytogenes, followed by a reduction in numbers of L. monocytogenes from 10 3 CFU/ml to below 10 CFU/ml after 32 days of incubation, coinciding with the detection of antilisterial compounds. The presence of a nonbacteriocin-producing strain of C. piscicola (A10a) prevented the growth of L monocytogenes during the 32-day incubation. The growth of L monocytogenes was strongly repressed on cold-Smoked Salmon in the presence of C. piscicola A9b and A10a, respectively. The initial cell numbers of L. monocytogenes that were found on Oxford plates incubated at 25°C reached low maximum cell counts of 104 and 2 X 10 3 after 14 and 20 days of storage in mixed culture with C. piscicola A9b and A10a.
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comparison of the microflora isolated from spoiled cold Smoked Salmon from three smokehouses
Food Research International, 1998Co-Authors: Lisbeth Truelstrup Hansen, Hans Henrik HussAbstract:Abstract The microflora on spoiled, sliced and vacuum packed, cold-Smoked Salmon from three smokehouses was quantified and characterized in two independent experiments. Large variations in the microflora were observed both within (i.e. among vacuum packs from the same batch) and among the smokehouses. Lactic acid bacteria dominated the microflora, which reached 107 cfu g−1. Total viable counts of microorganisms alone were not related to quality, though spoilage characteristics were typical for microbiological spoilage. Among the lactic acid bacteria, Lactobacillus curvatus (ca 52–55%) was the most common species in both experiments with Lactobacillus sake, Lactobacillus plantarum, Carnobacterium spp. and Leuconostoc spp. present in smaller numbers. In some cases, large numbers of Enterobacteriaceae were also present and identified species were Serratia liquefaciens, Enterobacter agglomerans and Hafnia alvei. The microflora on cold-Smoked Salmon appeared to be related to the source of contamination i.e. the raw material and/or the smokehouse rather than being specific for the product, thus rendering the identification of the specific spoilage organisms difficult.
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inhibition of listeria monocytogenes on cold Smoked Salmon by nisin and carbon dioxide atmosphere
International Journal of Food Microbiology, 1997Co-Authors: Lilian Nilsson, Hans Henrik Huss, Lone GramAbstract:The bacteriostatic and bacteriocidal effect of nisin in combination with carbon dioxide, NaCl and low temperature on the survival of Listeria monocytogenes was investigated in in vitro model studies and in trials with cold-Smoked Salmon. Addition of nisin caused various degrees of inhibition and sometimes death of L. monocytogenes in model experiments performed at 10°C. The antilisterial effect of nisin was improved in the presence of 100% CO2 and increasing NaCl concentrations (0.5 to 5.0% w/v). Minimal bactericidal concentrations (MBC) of nisin varied from 30 to more than 500 IU/ml. The most pronounced effect of nisin was found when 102 cfu/ml was grown in media with 5.0% NaCl and incubated in CO2 atmosphere (MBC=30 IU/ml). The bactericidal effect of nisin was reduced in air and vacuum, and did not increase systematically with increasing NaCl concentrations. In general, nisin concentration ≤50 IU/ml resulted in the survival and growth of L. monocytogenes in all combinations with other preservatives (NaCl, CO2). Addition of nisin (500 or 1000 IU/g) to cold-Smoked Salmon inoculated with L. monocytogenes and stored at 5°C delayed, but did not prevent growth of L. monocytogenes in vacuum-packs. Numbers of L. monocytogenes increased to 108 cfu/g in vacuum packed cold-Smoked Salmon in 8 days, whereas CO2 packing of cold-Smoked Salmon resulted in an 8-day lag phase of L. monocytogenes, with numbers eventually reaching 106 cfu/g in 27 days. Addition of nisin to CO2 packed cold-Smoked Salmon resulted in a 1 to 2 log reduction of L. monocytogenes followed by a lag phase of 8 and 20 days in Salmon with 500 and 1000 IU nisin/g, respectively. The levels of L. monocytogenes remained below 103 cfu/g during 27 days of storage at both concentrations of nisin.
Mu Ye - One of the best experts on this subject based on the ideXlab platform.
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effectiveness of chitosan coated plastic films incorporating antimicrobials in inhibition of listeria monocytogenes on cold Smoked Salmon
International Journal of Food Microbiology, 2008Co-Authors: Mu Ye, Hudaa Neetoo, Haiqiang ChenAbstract:Abstract The objective of this study was to evaluate the efficacy of chitosan-coated plastic films incorporating five Generally Recognized as Safe (GRAS) antimicrobials (nisin, sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS) and sodium benzoate (SB)) against Listeria monocytogenes on cold-Smoked Salmon. Salmon samples were surface-inoculated with a five-strain cocktail of L. monocytogenes and packaged in chitosan-coated plastic films containing 500 IU/cm2 of nisin, 9 mg/cm2 of SL, 0.5 mg/cm2 of SD, 0.6 mg/cm2 of PS, or 0.2 mg/cm2 of SB, and stored at room temperature (ca. 20 °C) for 10 days. The film incorporating SL was the most effective, completely inhibiting the growth of L. monocytogenes during 10 days of storage. L. monocytogenes in samples packaged in the other four antimicrobial films grew, but the increase in counts was lower than the control. The antilisterial efficacy of films containing lower concentrations of SL (2.3 mg/cm2 and 4.5 mg/cm2) and binary combinations SL, PS, SD, SB and nisin were subsequently evaluated. Among all the treatments, chitosan-coated plastic films with 4.5 mg/cm2 SL, 4.5 mg/cm2 SL–0.6 mg/cm2 PS and 2.3 mg/cm2 SL–500 IU/cm2 nisin were the most effective. These three most effective antimicrobial films were then tested at refrigerated temperature. They completely inhibited the growth of L. monocytogenes on Smoked Salmon for at least 6 weeks. Chitosan-coated plastic films containing 4.5 mg/cm2 SL can potentially assist the Smoked-Salmon processing industry in their efforts to control L. monocytogenes.
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potential antimicrobials to control listeria monocytogenes in vacuum packaged cold Smoked Salmon pâte and fillets
International Journal of Food Microbiology, 2008Co-Authors: Hudaa Neetoo, Mu Ye, Haiqiang ChenAbstract:Abstract In the wake of recent outbreaks associated with Listeria monocytogenes in ready-to-eat foods and an increasing desire for minimally processed foods, there has been a burgeoning interest in the use of natural antimicrobials by the food industry to control this pathogen. The minimum inhibitory concentrations (MICs) of nisin and salts of organic acids (sodium lactate (SL), sodium diacetate (SD), sodium benzoate (SB), and potassium sorbate (PS)) against twelve strains of L. monocytogenes in a TSBYE broth medium at 35 °C were determined. The MICs were strain-dependent and fell in the range of 0.00048–0.00190% for nisin, 4.60–5.60% for SL, 0.11–0.22% for SD, 0.25–0.50% for SB and 0.38–0.75% for PS, respectively. The two most antimicrobial-resistant strains were used as a cocktail in the following experiments to represent a worst case scenario. The five antimicrobials alone and in binary combinations were screened for their efficacy against the two-strain cocktail in TSBYE at sub-MIC and sub-legal levels at 35 °C. Seven effective antimicrobial treatments were then selected and evaluated for their long-term antilisterial effectiveness in cold-Smoked Salmon pâte and fillets during refrigerated storage (4 °C) of 3 and 6 weeks, respectively. The two most effective antimicrobial formulations for Smoked Salmon pâte, 0.25% SD and 2.4% SL/0.125% SD, were able to inhibit the growth of L. monocytogenes during the 3 weeks of storage. Surface application of 2.4% SL/0.125% SD was the most effective treatment for Smoked Salmon fillets which inhibited the growth of L. monocytogenes for 4 weeks. These antimicrobial treatments could be used by the Smoked Salmon industry in the U.S. and Europe in their efforts to control L. monocytogenes as they are effective against even the most antimicrobial-resistant strains tested in this study.
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use of nisin coated plastic films to control listeria monocytogenes on vacuum packaged cold Smoked Salmon
International Journal of Food Microbiology, 2008Co-Authors: Hudaa Neetoo, Mu Ye, Haiqiang Chen, Rolf D Joerger, D T Hicks, Dallas G HooverAbstract:Abstract Cold-Smoked (Salmo salar) Salmon samples were surface-inoculated with a cocktail of three nisin-resistant strains of L. monocytogenes (PSU1, PSU2 and PSU21) to a level of approximately 5 × 102 or 5 × 105 CFU/cm2 of Salmon surface. The inoculated Smoked Salmon samples were vacuum-packaged with control film (no nisin) or nisin-coated plastic films and stored at either 4 or 10 °C. When the inoculated Smoked Salmon samples were packaged with film coated with 2000 IU/cm2 of nisin, a reduction of 3.9 log CFU/cm2 (compared with control) was achieved at either temperature for samples inoculated with 5 × 102 CFU/cm2 of L. monocytogenes after 56 (4 °C) and 49 (10 °C) days of storage while reductions of 2.4 and 0.7 log CFU/cm2 were achieved for samples inoculated with a high level of L. monocytogenes (5 × 105 CFU/cm2) after 58 (4 °C) and 43 (10 °C) days, respectively. For samples packaged in film coated with 500 IU/cm2 of nisin, reductions of 0.5 and 1.7 log CFU/cm2 were achieved for samples inoculated with a low level of L. monocytogenes (5 × 102 CFU/cm2) after 56 (4 °C) and 49 (10 °C) days of storage while reductions of 1.8 and 0.8 log CFU/cm2 were achieved for samples inoculated with high level of L. monocytogenes after 58(4 °C) and 43 (10 °C) days, respectively. In addition, nisin inhibited the proliferation of background microbiota on Smoked Salmon in a concentration-dependent manner at both storage temperatures although the bacteriostatic effect was more pronounced at refrigeration temperature. This work highlights the potential for incorporating nisin into plastic films for enhancing the microbial safety of Smoked Salmon as well as controlling its microbial spoilage.
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Effectiveness of chitosan-coated plastic films incorporating antimicrobials in inhibition of Listeria monocytogenes on cold-Smoked Salmon
International Journal of Food Microbiology, 2008Co-Authors: Mu Ye, Hudaa Neetoo, Haiqiang ChenAbstract:The objective of this study was to evaluate the efficacy of chitosan-coated plastic films incorporating five Generally Recognized as Safe (GRAS) antimicrobials (nisin, sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS) and sodium benzoate (SB)) against Listeria monocytogenes on cold-Smoked Salmon. Salmon samples were surface-inoculated with a five-strain cocktail of L. monocytogenes and packaged in chitosan-coated plastic films containing 500 IU/cm2of nisin, 9 mg/cm2of SL, 0.5 mg/cm2of SD, 0.6 mg/cm2of PS, or 0.2 mg/cm2of SB, and stored at room temperature (ca. 20 °C) for 10 days. The film incorporating SL was the most effective, completely inhibiting the growth of L. monocytogenes during 10 days of storage. L. monocytogenes in samples packaged in the other four antimicrobial films grew, but the increase in counts was lower than the control. The antilisterial efficacy of films containing lower concentrations of SL (2.3 mg/cm2and 4.5 mg/cm2) and binary combinations SL, PS, SD, SB and nisin were subsequently evaluated. Among all the treatments, chitosan-coated plastic films with 4.5 mg/cm2SL, 4.5 mg/cm2SL-0.6 mg/cm2PS and 2.3 mg/cm2SL-500 IU/cm2nisin were the most effective. These three most effective antimicrobial films were then tested at refrigerated temperature. They completely inhibited the growth of L. monocytogenes on Smoked Salmon for at least 6 weeks. Chitosan-coated plastic films containing 4.5 mg/cm2SL can potentially assist the Smoked-Salmon processing industry in their efforts to control L. monocytogenes. © 2008 Elsevier B.V. All rights reserved.
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Use of nisin-coated plastic films to control Listeria monocytogenes on vacuum-packaged cold-Smoked Salmon.
International journal of food microbiology, 2007Co-Authors: Hudaa Neetoo, Mu Ye, Haiqiang Chen, Rolf D Joerger, D T Hicks, Dallas G HooverAbstract:Cold-Smoked (Salmo salar) Salmon samples were surface-inoculated with a cocktail of three nisin-resistant strains of L. monocytogenes (PSU1, PSU2 and PSU21) to a level of approximately 5 x 10(2) or 5 x 10(5) CFU/cm2 of Salmon surface. The inoculated Smoked Salmon samples were vacuum-packaged with control film (no nisin) or nisin-coated plastic films and stored at either 4 or 10 degrees C. When the inoculated Smoked Salmon samples were packaged with film coated with 2000 IU/cm2 of nisin, a reduction of 3.9 log CFU/cm2 (compared with control) was achieved at either temperature for samples inoculated with 5 x 10(2) CFU/cm(2 of L. monocytogenes after 56 (4 degrees C) and 49 (10 degrees C) days of storage while reductions of 2.4 and 0.7 log CFU/cm2 were achieved for samples inoculated with a high level of L. monocytogenes (5 x 10(5) CFU/cm2) after 58 (4 degrees C) and 43 (10 degrees C) days, respectively. For samples packaged in film coated with 500 IU/cm2 of nisin, reductions of 0.5 and 1.7 log CFU/cm2 were achieved for samples inoculated with a low level of L. monocytogenes (5 x 10(2) CFU/cm2) after 56 (4 degrees C) and 49 (10 degrees C) days of storage while reductions of 1.8 and 0.8 log CFU/cm2 were achieved for samples inoculated with high level of L. monocytogenes after 58(4 degrees C) and 43 (10 degrees C) days, respectively. In addition, nisin inhibited the proliferation of background microbiota on Smoked Salmon in a concentration-dependent manner at both storage temperatures although the bacteriostatic effect was more pronounced at refrigeration temperature. This work highlights the potential for incorporating nisin into plastic films for enhancing the microbial safety of Smoked Salmon as well as controlling its microbial spoilage.
Hudaa Neetoo - One of the best experts on this subject based on the ideXlab platform.
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Prior frozen storage enhances the effect of edible coatings against Listeria monocytogenes on cold-Smoked Salmon during subsequent refrigerated storage
Journal of Applied Microbiology, 2011Co-Authors: M. Ye, Hudaa Neetoo, H. ChenAbstract:Aims: Listeria monocytogenes is a major safety concern for ready-to-eat foods. The overall objective of this study was to investigate whether prior frozen storage could enhance the efficacy of edible coatings against L. monocytogenes on cold-Smoked Salmon during subsequent refrigerated storage. Methods and Results: A formulation consisting of sodium lactate (SL, 1·2–2·4%) and sodium diacetate (SD, 0·125–0·25%) or 2·5% Opti.Form (a commercial formulation of SL and SD) was incorporated into each of five edible coatings: alginate, κ-carrageenan, pectin, gelatin and starch. The coatings were applied onto the surface of cold-Smoked Salmon slices inoculated with L. monocytogenes at a level of 500 CFU cm−2. In the first phase, the slices were first frozen at −18°C for 6 days and stored at 22°C for 6 days. Alginate, gelatin and starch appeared to be the most effective carriers. In the second phase, cold-Smoked Salmon slices were inoculated with L. monocytogenes, coated with alginate, gelatin or starch with or without the antimicrobials and stored frozen at −18°C for 12 months. Every 2 months, samples were removed from the freezer and kept at 4°C for 30 days. Prior frozen storage at −18°C substantially enhanced the antilisterial efficacy of the edible coatings with or without antimicrobials during the subsequent refrigerated storage. Conclusions: Plain coatings with ≥2 months frozen storage and antimicrobial edible coatings represent an effective intervention to inhibit the growth of L. monocytogenes on cold-Smoked Salmon. Significance and Impact of the Study: This study demonstrates the effectiveness of the conjunct application of frozen storage and edible coatings to control the growth of L. monocytogenes to enhance the microbiological safety of cold-Smoked Salmon.
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effectiveness of chitosan coated plastic films incorporating antimicrobials in inhibition of listeria monocytogenes on cold Smoked Salmon
International Journal of Food Microbiology, 2008Co-Authors: Mu Ye, Hudaa Neetoo, Haiqiang ChenAbstract:Abstract The objective of this study was to evaluate the efficacy of chitosan-coated plastic films incorporating five Generally Recognized as Safe (GRAS) antimicrobials (nisin, sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS) and sodium benzoate (SB)) against Listeria monocytogenes on cold-Smoked Salmon. Salmon samples were surface-inoculated with a five-strain cocktail of L. monocytogenes and packaged in chitosan-coated plastic films containing 500 IU/cm2 of nisin, 9 mg/cm2 of SL, 0.5 mg/cm2 of SD, 0.6 mg/cm2 of PS, or 0.2 mg/cm2 of SB, and stored at room temperature (ca. 20 °C) for 10 days. The film incorporating SL was the most effective, completely inhibiting the growth of L. monocytogenes during 10 days of storage. L. monocytogenes in samples packaged in the other four antimicrobial films grew, but the increase in counts was lower than the control. The antilisterial efficacy of films containing lower concentrations of SL (2.3 mg/cm2 and 4.5 mg/cm2) and binary combinations SL, PS, SD, SB and nisin were subsequently evaluated. Among all the treatments, chitosan-coated plastic films with 4.5 mg/cm2 SL, 4.5 mg/cm2 SL–0.6 mg/cm2 PS and 2.3 mg/cm2 SL–500 IU/cm2 nisin were the most effective. These three most effective antimicrobial films were then tested at refrigerated temperature. They completely inhibited the growth of L. monocytogenes on Smoked Salmon for at least 6 weeks. Chitosan-coated plastic films containing 4.5 mg/cm2 SL can potentially assist the Smoked-Salmon processing industry in their efforts to control L. monocytogenes.
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potential antimicrobials to control listeria monocytogenes in vacuum packaged cold Smoked Salmon pâte and fillets
International Journal of Food Microbiology, 2008Co-Authors: Hudaa Neetoo, Mu Ye, Haiqiang ChenAbstract:Abstract In the wake of recent outbreaks associated with Listeria monocytogenes in ready-to-eat foods and an increasing desire for minimally processed foods, there has been a burgeoning interest in the use of natural antimicrobials by the food industry to control this pathogen. The minimum inhibitory concentrations (MICs) of nisin and salts of organic acids (sodium lactate (SL), sodium diacetate (SD), sodium benzoate (SB), and potassium sorbate (PS)) against twelve strains of L. monocytogenes in a TSBYE broth medium at 35 °C were determined. The MICs were strain-dependent and fell in the range of 0.00048–0.00190% for nisin, 4.60–5.60% for SL, 0.11–0.22% for SD, 0.25–0.50% for SB and 0.38–0.75% for PS, respectively. The two most antimicrobial-resistant strains were used as a cocktail in the following experiments to represent a worst case scenario. The five antimicrobials alone and in binary combinations were screened for their efficacy against the two-strain cocktail in TSBYE at sub-MIC and sub-legal levels at 35 °C. Seven effective antimicrobial treatments were then selected and evaluated for their long-term antilisterial effectiveness in cold-Smoked Salmon pâte and fillets during refrigerated storage (4 °C) of 3 and 6 weeks, respectively. The two most effective antimicrobial formulations for Smoked Salmon pâte, 0.25% SD and 2.4% SL/0.125% SD, were able to inhibit the growth of L. monocytogenes during the 3 weeks of storage. Surface application of 2.4% SL/0.125% SD was the most effective treatment for Smoked Salmon fillets which inhibited the growth of L. monocytogenes for 4 weeks. These antimicrobial treatments could be used by the Smoked Salmon industry in the U.S. and Europe in their efforts to control L. monocytogenes as they are effective against even the most antimicrobial-resistant strains tested in this study.
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use of nisin coated plastic films to control listeria monocytogenes on vacuum packaged cold Smoked Salmon
International Journal of Food Microbiology, 2008Co-Authors: Hudaa Neetoo, Mu Ye, Haiqiang Chen, Rolf D Joerger, D T Hicks, Dallas G HooverAbstract:Abstract Cold-Smoked (Salmo salar) Salmon samples were surface-inoculated with a cocktail of three nisin-resistant strains of L. monocytogenes (PSU1, PSU2 and PSU21) to a level of approximately 5 × 102 or 5 × 105 CFU/cm2 of Salmon surface. The inoculated Smoked Salmon samples were vacuum-packaged with control film (no nisin) or nisin-coated plastic films and stored at either 4 or 10 °C. When the inoculated Smoked Salmon samples were packaged with film coated with 2000 IU/cm2 of nisin, a reduction of 3.9 log CFU/cm2 (compared with control) was achieved at either temperature for samples inoculated with 5 × 102 CFU/cm2 of L. monocytogenes after 56 (4 °C) and 49 (10 °C) days of storage while reductions of 2.4 and 0.7 log CFU/cm2 were achieved for samples inoculated with a high level of L. monocytogenes (5 × 105 CFU/cm2) after 58 (4 °C) and 43 (10 °C) days, respectively. For samples packaged in film coated with 500 IU/cm2 of nisin, reductions of 0.5 and 1.7 log CFU/cm2 were achieved for samples inoculated with a low level of L. monocytogenes (5 × 102 CFU/cm2) after 56 (4 °C) and 49 (10 °C) days of storage while reductions of 1.8 and 0.8 log CFU/cm2 were achieved for samples inoculated with high level of L. monocytogenes after 58(4 °C) and 43 (10 °C) days, respectively. In addition, nisin inhibited the proliferation of background microbiota on Smoked Salmon in a concentration-dependent manner at both storage temperatures although the bacteriostatic effect was more pronounced at refrigeration temperature. This work highlights the potential for incorporating nisin into plastic films for enhancing the microbial safety of Smoked Salmon as well as controlling its microbial spoilage.
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Effectiveness of chitosan-coated plastic films incorporating antimicrobials in inhibition of Listeria monocytogenes on cold-Smoked Salmon
International Journal of Food Microbiology, 2008Co-Authors: Mu Ye, Hudaa Neetoo, Haiqiang ChenAbstract:The objective of this study was to evaluate the efficacy of chitosan-coated plastic films incorporating five Generally Recognized as Safe (GRAS) antimicrobials (nisin, sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS) and sodium benzoate (SB)) against Listeria monocytogenes on cold-Smoked Salmon. Salmon samples were surface-inoculated with a five-strain cocktail of L. monocytogenes and packaged in chitosan-coated plastic films containing 500 IU/cm2of nisin, 9 mg/cm2of SL, 0.5 mg/cm2of SD, 0.6 mg/cm2of PS, or 0.2 mg/cm2of SB, and stored at room temperature (ca. 20 °C) for 10 days. The film incorporating SL was the most effective, completely inhibiting the growth of L. monocytogenes during 10 days of storage. L. monocytogenes in samples packaged in the other four antimicrobial films grew, but the increase in counts was lower than the control. The antilisterial efficacy of films containing lower concentrations of SL (2.3 mg/cm2and 4.5 mg/cm2) and binary combinations SL, PS, SD, SB and nisin were subsequently evaluated. Among all the treatments, chitosan-coated plastic films with 4.5 mg/cm2SL, 4.5 mg/cm2SL-0.6 mg/cm2PS and 2.3 mg/cm2SL-500 IU/cm2nisin were the most effective. These three most effective antimicrobial films were then tested at refrigerated temperature. They completely inhibited the growth of L. monocytogenes on Smoked Salmon for at least 6 weeks. Chitosan-coated plastic films containing 4.5 mg/cm2SL can potentially assist the Smoked-Salmon processing industry in their efforts to control L. monocytogenes. © 2008 Elsevier B.V. All rights reserved.
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Quantitative Risk Assessment of Listeria monocytogenes in French cold-Smoked Salmon: II. Risk Characterization
Risk Analysis, 2017Co-Authors: Regis Pouillot, Aurélie Mahé, Véronique Goulet, Marie Laure Delignette-muller, Marie CornuAbstract:A model for the assessment of exposure to Listeria monocytogenes from cold?Smoked Salmon consumption in France was presented in the first of this pair of articles (Pouillot et al., 2007, Risk Analysis, 27:683?700). In the present study, the exposure model output was combined with an internationally accepted hazard characterization model, adapted to the French situation, to assess the risk of invasive listeriosis from cold?Smoked Salmon consumption in France in a second?order Monte?Carlo simulation framework. The annual number of cases of invasive listeriosis due to cold?Smoked Salmon consumption in France is estimated to be 307, with a very large credible interval ([10; 12 453]), reflecting data uncertainty. This uncertainty is mainly associated with the dose-response model. Risk would be efficiently reduced through a decrease in the prevalence of L. monocytogenes or better control of the last steps of the cold?chain (shorter and/or colder storage during the consumer step). Reduction of the initial contamination levels of the contaminated products and improvement in the first steps of the cold?chain do not seem to be promising strategies for reducing the estimated risk. Despite the significant uncertainty associated with the predictions, this model provides a scientific base for risk managers and food business operators to manage the risk linked to cold-Smoked Salmon contaminated with Listeria moncytogenes and to apply the recent risk-based concept of risk management metrics illustrated here by the FSO (food safety objective).
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quantitative risk assessment of listeria monocytogenes in french cold Smoked Salmon ii risk characterization
Risk Analysis, 2009Co-Authors: Regis Pouillot, Aurélie Mahé, Véronique Goulet, Marie Laure Delignettemuller, Marie CornuAbstract:A model for the assessment of exposure to Listeria monocytogenes from cold†Smoked Salmon consumption in France was presented in the first of this pair of articles (Pouillot et al., 2007, Risk Analysis, 27:683–700). In the present study, the exposure model output was combined with an internationally accepted hazard characterization model, adapted to the French situation, to assess the risk of invasive listeriosis from cold†Smoked Salmon consumption in France in a second†order Monte Carlo simulation framework. The annual number of cases of invasive listeriosis due to cold†Smoked Salmon consumption in France is estimated to be 307, with a very large credible interval ([10; 12,453]), reflecting data uncertainty. This uncertainty is mainly associated with the dose†response model. Despite the significant uncertainty associated with the predictions, this model provides a scientific base for risk managers and food business operators to manage the risk linked to cold†Smoked Salmon contaminated with L. monocytogenes. Under the modeling assumptions, risk would be efficiently reduced through a decrease in the prevalence of L. monocytogenes or better control of the last steps of the cold chain (shorter and/or colder storage during the consumer step), whereas reduction of the initial contamination levels of the contaminated products and improvement in the first steps of the cold chain do not seem to be promising strategies. An attempt to apply the recent risk†based concept of FSO (food safety objective) on this example underlines the ambiguity in practical implementation of the risk management metrics and the need for further elaboration on these concepts.
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use of bayesian modelling in risk assessment application to growth of listeria monocytogenes and food flora in cold Smoked Salmon
International Journal of Food Microbiology, 2006Co-Authors: Marie Laure Delignettemuller, Marie Cornu, Regis Pouillot, Jeanâ Baptiste DenisAbstract:An attempt to use a Bayesian approach to model variability and uncertainty separately in microbial growth in a risk assessment is presented. It was conducted within the framework of a French project aiming at assessing the exposure to Listeria monocytogenes in cold-Smoked Salmon. The chosen model describes the effect of time and temperature on bacterial growth. A Bayesian approach close to the one proposed by Pouillot et al. [Int. J. Food Microbiol. 81 (2003) 87] is used to estimate the variability and uncertainty of growth parameters from both literature data and data experimentally acquired during the project. Variability between strains and between products is taken into account. The growth of the food flora of cold-Smoked Salmon is also modelled by the same method. The results obtained for both models are used to predict the simultaneous growth of L. monocytogenes and food flora in cold-Smoked Salmon with a competitive model, expressing variability and uncertainty through a second-order Monte Carlo simulation.
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effect of temperature water phase salt and phenolic contents on listeria monocytogenes growth rates on cold Smoked Salmon and evaluation of secondary models
International Journal of Food Microbiology, 2006Co-Authors: Marie Cornu, A. Beaufort, S. Rudelle, L Laloux, H Bergis, Nicolas Miconnet, T Serot, Marie Laure DelignettemullerAbstract:Salting and smoking are ancient processes for fish preservation. The effects of salt and phenolic smoke compounds on the growth rate of L. monocytogenes in cold-Smoked Salmon were investigated through physico-chemical analyses, challenge tests on surface of cold-Smoked Salmon at 4 degrees C and 8 degrees C, and a survey of the literature. Estimated growth rates were compared to predictions of existing secondary models, taking into account the effects of temperature, water phase salt content, phenolic content, and additional factors (e.g. pH, lactate, dissolved CO2). The secondary model proposed by Devlieghere et al. [Devlieghere, F., Geeraerd, A.H., Versyck, K.J., Vandewaetere, B., van Impe, J., Debevere, J., 2001. Growth of Listeria monocytogenes in modified atmosphere packed cooked meat products: a predictive model. Food Microbiology 18, 53-66.] and modified by Gim?z and Dalgaard [Gim?z, B., Dalgaard, P., 2004. Modelling and predicting the simultaneous growth of Listeria monocytogenes and spoilage micro-organisms in cold-Smoked Salmon. Journal of Applied Microbiology 96, 96-109.] appears appropriate. However, further research is needed to understand all effects affecting growth of L. monocytogenes in cold-Smoked Salmon and to obtain fully validated predictive models for use in quantitative risk assessment.
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a contribution to the improvement of listeria monocytogenes enumeration in cold Smoked Salmon
International Journal of Food Microbiology, 2004Co-Authors: Nathalie Gnanou Besse, Marie Cornu, A. Beaufort, Nelly Audinet, Pierre Colin, Bertrand LombardAbstract:Abstract For the enumeration of Listeria monocytogenes in food, a sensitive enumeration method based on membrane filtration followed by transfer of the filter to a selective medium has been developed. This study was carried out with cold-Smoked Salmon, a product likely to be contaminated with L. monocytogenes. The operating protocol utilizes three filtration runs in parallel (5, 15 and 30 ml) of a 1 in 10 dilution of the Salmon suspension through 0.45-μm pore-size cellulose ester membranes, and then culture of the filters on Aloa agar (AES Laboratoires, Combourg, France). The results obtained with the technique were compared with those from the reference EN ISO 11290-2 method and found to provide more precise results in the enumeration of L. monocytogenes from both artificially and naturally contaminated cold-Smoked Salmon. Moreover, for several samples contaminated at low levels, L. monocytogenes could be recovered only by the filtration method. The examination of increasing volumes of Salmon suspension enabled readable results to be obtained for all levels of L. monocytogenes and competitive microflora investigated. In most cases, the optimised operating protocol enabled 5.1 g of Salmon to be examined, instead of 0.01–0.1 g with the reference EN ISO 11290-2 method, thus improving the sensitivity of the method.
