scholarly journals An improved selective isolation medium for the recovery of Listeria monocytogenes from smoked fish

2003 ◽  
Vol 36 (4) ◽  
pp. 230-233 ◽  
Author(s):  
A.A.N. Neamatallah ◽  
S.J. Dewar ◽  
B. Austin
Keyword(s):  
Listeria Monocytogenes ◽  
Selective Isolation ◽  
Isolation Medium ◽  
Smoked Fish

Listeria in Seafoods: A Review

1992 ◽  
Vol 55 (12) ◽  
pp. 1009-1015 ◽  
Author(s):  
RONDA M. DILLON ◽  
THAKOR R. PATEL
Keyword(s):  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Drug Administration ◽  
Food And Drug Administration ◽  
Environmental Contaminant ◽  
Fresh Waters ◽  
Smoked Fish ◽  
Seafood Products ◽  
Crab Meat

Listeria is an environmental contaminant which has been isolated from marine and fresh waters, as well as various seafoods. Furthermore, Listeria, including Listeria monocytogenes, has been isolated from processed seafood products such as smoked fish, cooked and frozen seafoods, marinated fish, surimi products, etc. The pathogen, L. monocytogenes, does have a certain degree of heat resistance. It was found to survive in internally infected shrimp after boiled for up to 5 min. However, the commercial pasteurization process for crab meat was found to be sufficient to inactivate Listeria. The current recovery methodology for L. monocytogenes from seafoods is the Food and Drug Administration Listeria protocol.

Inactivation of Listeria monocytogenes on Hot-smoked Salmon by the Interaction of Heat and Smoke or Liquid Smoke†

1997 ◽  
Vol 60 (6) ◽  
pp. 649-654 ◽  
Author(s):  
FRANK T. POYSKY ◽  
ROHINEE N. PARANJPYE ◽  
MARK E. PETERSON ◽  
GRETCHEN A. PELROY ◽  
ANNE E. GUTTMAN ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Minimum Temperature ◽  
Soluble Fraction ◽  
Internal Temperature ◽  
Lethal Temperature ◽  
Entire Process ◽  
Smoked Fish ◽  
Liquid Smoke ◽  
Full Strength ◽  
Smoked Salmon

L. monocytogenes was inoculated onto the surface of brined salmon steaks and heat processed in a commercial smokehouse to simulate a hot process for preparing smoked fish. The minimum temperature required for inactivation of L. monocytogenes was 153°F (67.2°C) when generated smoke was applied throughout the entire process. When generated smoke was added only during the last half of the process, L. monocytogenes was recovered from steaks heated to temperatures as high as 176°F (80.0°C). When smoke was not applied during the process, L. monocytogenes survived on steaks heated to internal temperatures between 131°F and 181°F (55.0 to 82.8°C) but was not isolated from steaks heated above 181°F (82.8°C). When liquid smoke CharSol C-l0 was applied as a full-strength (100%) dip before processing, L. monocytogenes was inactivated in samples processed at temperatures as low as 138°F (58.9°C). When liquid smoke l0-Poly or CharSol C-l0 was applied at a concentration of 50%, the lethal temperature was increased to the range of 145 to 150°F (62.8 to 65.6°C). With further dilution of C-l0 to 25% and 10% the inactivation temperatures increased to 156°F (68.9°C) and 163°F (72.8°C). A full-strength dip of CharOil, the oil-soluble fraction of CharSol C-l0, was less effective, and L. monocytogenes survived in salmon steaks processed to an internal temperature of 166°F (74.4°C), the highest temperature tested with this liquid smoke. This study provides evidence that heat alone is not reliable for inactivation of L. monocytogenes during the hot-smoking process. The proper stage and duration of smoke application or proper composition and concentration of liquid smoke in combination with heat are critical for inactivation of the organism.

Listeria monocytogenes Contamination Patterns for the Smoked Fish Processing Environment and for Raw Fish

2003 ◽  
Vol 66 (1) ◽  
pp. 52-60 ◽  
Author(s):  
ADAM D. HOFFMAN ◽  
KENNETH L. GALL ◽  
DAWN M. NORTON ◽  
MARTIN WIEDMANN
Keyword(s):  
Listeria Monocytogenes ◽  
Environmental Contamination ◽  
West Coast ◽  
Environmental Samples ◽  
Raw Materials ◽  
Processing Plant ◽  
Fish Processing ◽  
Smoked Fish ◽  
Fish Samples ◽  
Raw Fish

Reliable data on the sources of Listeria monocytogenes contamination in cold-smoked fish processing are crucial in designing effective intervention strategies. Environmental samples (n = 512) and raw fish samples (n = 315) from two smoked fish processing facilities were screened for L. monocytogenes, and all isolates were subtyped by automated ribotyping to examine the relationship between L. monocytogenes contamination from raw materials and that from environmental sites. Samples were collected over two 8-week periods in early spring and summer. The five types of raw fish tested included lake whitefish, sablefish, farm-raised Norwegian salmon, farm-raised Chilean salmon, and feral (wild-caught) salmon from the U.S. West Coast. One hundred fifteen environmental samples and 46 raw fish samples tested positive for L. monocytogenes. Prevalence values for environmental samples varied significantly (P < 0.0001) between the two plants; plant A had a prevalence value of 43.8% (112 of 256 samples), and plant B had a value of 1.2% (3 of 256 samples). For plant A, 62.5% of drain samples tested positive for L. monocytogenes, compared with 32.3% of samples collected from other environmental sites and 3.1% of samples collected from food contact surfaces. Ribotyping identified 11 subtypes present in the plant environments. Multiple subtypes, including four subtypes not found on any raw fish, were found to persist in plant A throughout the study. Contamination prevalence values for raw fish varied from 3.6% (sablefish) to 29.5% (U.S. West Coast salmon), with an average overall prevalence of 14.6%. Sixteen separate L. monocytogenes subtypes were present on raw fish, including nine that were not found in the plant environment. Our results indicate a disparity between the subtypes found on raw fish and those found in the processing environment. We thus conclude that environmental contamination is largely separate from that of incoming raw materials and includes strains persisting, possibly for years, within the plant. Operational and sanitation procedures appear to have a significant impact on environmental contamination, with both plants having similar prevalence values for raw materials but disparate contamination prevalence values for the environmental sites. We also conclude that regular L. monocytogenes testing of drains, combined with molecular subtyping of the isolates obtained, allows for efficient monitoring of persistent L. monocytogenes contamination in a processing plant.

Prevalence and Numbers of Listeria monocytogenes in Various Ready-to-Eat Foods over a 5-Year Period in Estonia

2019 ◽  
Vol 82 (4) ◽  
pp. 597-604 ◽  
Author(s):  
JULIA KOSKAR ◽  
TOOMAS KRAMARENKO ◽  
KADRIN MEREMÄE ◽  
MAIU KUNINGAS ◽  
JELENA SÕGEL ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Risk Groups ◽  
Food Samples ◽  
Safety Criterion ◽  
Fish Products ◽  
Product Categories ◽  
Salted Fish ◽  
Smoked Fish ◽  
High Prevalence ◽  
Fish Product

ABSTRACT The prevalence and numbers of Listeria monocytogenes in various categories of ready-to-eat (RTE) food products taken from retail outlets and food industries over a 5-year period are presented. A total of 30,016 RTE food samples were analyzed for L. monocytogenes prevalence, and 3.6% were found to be positive. The highest prevalence was found for RTE fish and fish products (11.6%), especially for lightly salted and cold-smoked fish products. The overall prevalence of L. monocytogenes in other food categories was low, within the range of 0 to 3.9%. In addition, 14,342 RTE food samples were analyzed to determine the numbers of L. monocytogenes. A food safety criterion of 100 CFU/g was exceeded for 0.3% of RTE food samples. Samples most often exceeding the legal safety limit were from the RTE salted and cold-smoked fish product categories. High prevalence, 28.6 and 26.5%, respectively, and high numbers of L. monocytogenes among salted fish and cold-smoked fish products indicate a risk of listeriosis, especially for susceptible risk groups. The results of the current study can be used at both the national and the international levels to update the perception of the L. monocytogenes risk deriving from RTE foods. HIGHLIGHTS

Antilisterial Activity of a Carnobacterium piscicola Isolated from Brazilian Smoked Fish (Surubim [Pseudoplatystoma sp.]) and Its Activity against a Persistent Strain of Listeria monocytogenes Isolated from Surubim

2005 ◽  
Vol 68 (10) ◽  
pp. 2068-2077 ◽  
Author(s):  
VIRGÍNIA F. ALVES ◽  
ELAINE C. P. DE MARTINIS ◽  
MARIA TERESA DESTRO ◽  
BIRTE FONNESBECH VOGEL ◽  
LONE GRAM
Keyword(s):  
Listeria Monocytogenes ◽  
Freshwater Fish ◽  
Random Amplified Polymorphic Dna ◽  
Model Systems ◽  
Fish Products ◽  
Tropical Regions ◽  
Smoked Fish ◽  
Smoked Salmon ◽  
Carnobacterium Piscicola

Data on the prevalence and growth of Listeria monocytogenes in lightly preserved fish products from subtropical and tropical regions are very scarce. Our research describes L. monocytogenes that was detected in 5% of the packages of cold-smoked surubim, a native Brazilian freshwater fish that we analyzed, and shows that the strains isolated were of the same random amplified polymorphic DNA subtype as the strains that were isolated from the same factory 4 years earlier. A bacteriocinogenic strain of Carnobacterium piscicola (strain C2), isolated from vacuum-packed cold-smoked surubim, and two C. piscicola strains, isolated from vacuum-packed, cold-smoked salmon, were capable of limiting or completely inhibiting the growth of an L. monocytogenes (strain V2) isolated from surubim in fish peptone model systems incubated at 10°C. Mono-cultures of L. monocytogenes reached 108 CFU/ml (g), whereas the growth of L. monocytogenes was completely inhibited by C. piscicola C2. The bacteriocinogenic C. piscicola A9b+ and its nonbacteriocinogenic mutant A9b− reduced maximum Listeria levels by 2 to 3 log units. Both bacteriocinogenic C. piscicola strains prevented listerial growth in cold-smoked fish juices (surubim and salmon). Although the carnobacteria grew poorly on cold-smoked surubim at 10°C, the strains were able to reduce maximum Listeria counts by 1 to 3 log units in an artificially inoculated product (surubim). We conclude that Brazilian smoked fish products harbor L. monocytogenes and should be stabilized against the growth of the organism. C. piscicola C2 has the potential for use as a bioprotective culture in surubim and other lightly preserved fish, but further studies are required to optimize its effect.

Comparison of Selective Direct Plating Media for Enumeration and Recovery of L. monocytogenes from Cold-process (smoked) Fish

1992 ◽  
Vol 55 (11) ◽  
pp. 905-909 ◽  
Author(s):  
ROHINEE N. PARANJPYE ◽  
GRETCHEN A. PELROY ◽  
MARK E. PETERSON ◽  
FRANK T. POYSKY ◽  
PAUL J. HOLLAND ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Lithium Chloride ◽  
Indicator System ◽  
Water Phase ◽  
Direct Plating ◽  
Selective Media ◽  
Smoked Fish ◽  
Smoked Salmon ◽  
Selective Agar ◽  
Added Salt

Three selective media were evaluated for direct plating recovery and enumeration of Listeria monocytogenes in the presence of high levels of a variety of microorganisms occurring on cold-process (smoked) salmon products. Sliced salmon was brined to contain either no added salt, 3, or 5% water-phase NaCl, or 3 or 5% NaCl plus 140 ppm NaNO2. The slices were packaged in oxygen-permeable film or sealed under vacuum in oxygen-impermeable film, and stored at 10°C or 5°C until total microbial loads reached 106 to 109 CFU/g. Oxford formulation of Listeria selective agar and Lee's modification of Listeria selective agar achieved quantitative recovery of 102 cells per ml of L. monocytogenes strain Scott A in the presence of diluted slurries of these fish containing 104 to 108 CFU/ml of background organisms. A modification of lithium chloride-phenylethanol-moxalactam agar containing an iron-esculin indicator system sometimes failed because of interfering growth by the background microflora.

Listeria monocytogenes in Smoked Salmon and Other Smoked Fish at Retail in Italy: Frequency of Contamination and Strain Characterization in Products from Different Manufacturers

2017 ◽  
Vol 80 (2) ◽  
pp. 271-278 ◽  
Author(s):  
Vicdalia Aniela Acciari ◽  
Marina Torresi ◽  
Luigi Iannetti ◽  
Silvia Scattolini ◽  
Francesco Pomilio ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Confidence Interval ◽  
Maximum Level ◽  
Restriction Enzymes ◽  
Pulsed Field Gel Electrophoresis ◽  
Strain Characterization ◽  
Smoked Fish ◽  
Smoked Salmon ◽  
Italian Market ◽  
Different Levels

ABSTRACT Seven hundred seventy-eight samples of packaged smoked fish (774 smoked salmon and 4 smoked swordfish) on sale in Italy, from 50 different manufacturers located in 12 European Union countries, were purchased from the Italian market between May and December 2011. The surface temperatures of the samples on sale ranged from 0 to 13°C (3.4 ± 1.5°C, mean ± SD). Six hundred eighty (87.4%) of 778 samples were stored at ≤4°C. One hundred fifty-seven samples (20.2%, 95% confidence interval 17.5 to 23.1%) were contaminated by Listeria monocytogenes, with 26 samples (3.3%, 95% confidence interval 2.3 to 4.8%) at levels >100 CFU/g. The maximum level of contamination was 1.3 ×106 CFU/g. The differences in the level of contamination of smoked fish between countries (χ2 = 91.54, P < 0.05) and manufacturers (χ2 = 193.22, P < 0.05) were significant. The frequency of detection for products from different manufacturing premises ranged from 0 to 76.9%. Serotyping by serological agglutination revealed that the main serotypes detected were 1/2a (65.3%) and 1/2b (22.4%). Pulsed-field gel electrophoresis typing with restriction enzymes AscI and ApaI yielded 36 pulsotypes from 144 isolates, clustering into 17 groups. Eight main pulsotypes accounted for 70.8% of the isolates. Three of the main pulsotypes were exclusively from products of a single manufacturer. In general, products from the same manufacturer showed genetic homogeneity, with one strongly prevalent pulsotype. Different manufacturers usually showed very different levels of contamination of the final product, confirming the importance of the management of process hygiene for controlling L. monocytogenes contamination.

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