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

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.

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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

Journal of Food Protection ◽

10.4315/0362-028x-68.10.2068 ◽

2005 ◽

Vol 68 (10) ◽

pp. 2068-2077 ◽

Cited By ~ 20

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.

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

Journal of Food Protection ◽

10.4315/0362-028x-55.11.905 ◽

1992 ◽

Vol 55 (11) ◽

pp. 905-909 ◽

Cited By ~ 7

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.

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

Journal of Food Protection ◽

10.4315/0362-028x.jfp-15-599 ◽

2017 ◽

Vol 80 (2) ◽

pp. 271-278 ◽

Cited By ~ 13

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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Identification and serotyping of Listeria monocytogenes, isolated from various salmon products, sold in retail market in Lithuania

Italian Journal of Food Safety ◽

10.4081/ijfs.2021.9341 ◽

2021 ◽

Vol 10 (3) ◽

Author(s):

Ineta Simonavičienė ◽

Gintarė Zakariene ◽

Aušra Lozoraitytė ◽

Gintarė Zaborskienė ◽

Gediminas Gerulis ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Multiplex Pcr ◽

Local Market ◽

Microbiological Analysis ◽

Retail Market ◽

Fish Products ◽

Smoked Fish ◽

Smoked Salmon ◽

Study Results ◽

Fish Product

Cold smoked salmon products (belly flaps, pieces, fillet, and loin) obtained from the retail market in Lithuania were tested for the presence of L. monocytogenes. It was found that contamination of the cold smoked fish products with Listeria spp. depends on the type of the product. Contamination with listeria in salmon belly flaps was 7.5 times higher than in the loin (P<0.05), 1.8 times higher than in the pieces (P<0.05) and 30 times higher than in the fillet (P<0.05). Microbiological analysis showed that 32.5% (P<0.05) of the fish product samples were infected with L. monocytogenes, while multiplex PCR confirmed 31.25% positive samples (P<0.01). According to the study results, L. monocytogenes strains were divided into two serotypes: 4b (94.6%) and 1/2a (5.4%). High contamination of the products with Listeria spp. showed that cold smoked salmon products, sold in local market, can be a reason of human listeriosis in Lithuania.

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Parameters for Control of Listeria monocytogenes in Smoked Fishery Products: Sodium Chloride and Packaging Method

Journal of Food Protection ◽

10.4315/0362-028x-56.11.938 ◽

1993 ◽

Vol 56 (11) ◽

pp. 938-943 ◽

Cited By ~ 34

Author(s):

MARK E. PETERSON ◽

GRETCHEN A. PELROY ◽

ROHINEE N. PARANJPYE ◽

FRANK T. POYSKY ◽

JAMIE S. ALMOND ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Sodium Chloride ◽

Vacuum Packaging ◽

Water Phase ◽

Smoked Fish ◽

Rate Of Growth ◽

A Cells ◽

Smoked Salmon ◽

Nacl Concentration ◽

Fishery Products

The behavior of Listeria monocytogenes (10 Scott A cells per g) in cold-process (smoked) salmon containing 3, 5, or 6% water-phase NaCl was evaluated during 30 to 40 d storage at 5 or 10°C in either oxygen-permeable film or vacuum-sealed impermeable film. At 10°C, L. monocytogenes grew to 106 to 108 CFU/g by the second week, with no differences attributed to NaCl concentration except for an initial lag in the 6% NaCl samples. Vacuum packaging suppressed growth of L. monocytogenes by 10- to 100-fold in samples with 3 or 5% NaCl. Inhibition related to NaCl concentration was most apparent at 5°C and L. monocytogenes populations were held below 102 CFU/g by 6% NaCl. Growth of a 327 CFU/g inoculum was about 10-fold greater than a 10 CFU/g inoculum at 10°C and 100-fold greater at 5°C. Growth of two strains isolated from naturally contaminated, commercially prepared, cold-smoked fish did not differ from Scott A. The use of sugar in the product did not influence growth of L. monocytogenes. Maximum populations of aerobic microorganisms reached at 5 and 10°C were similar, although the rate of growth was somewhat delayed at 5°C, and some inhibition was shown by 5 and 6% NaCl and by vacuum packaging.

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Effect of Salt, Smoke Compound, and Storage Temperature on the Growth of Listeria monocytogenes in Simulated Smoked Salmon†

Journal of Food Protection ◽

10.4315/0362-028x-70.10.2321 ◽

2007 ◽

Vol 70 (10) ◽

pp. 2321-2328 ◽

Cited By ~ 17

Author(s):

CHENG-AN HWANG

Keyword(s):

Listeria Monocytogenes ◽

Storage Temperature ◽

Control Measures ◽

Lag Phase ◽

Phase Duration ◽

Liquid Smoke ◽

Smoked Salmon ◽

And Storage ◽

Storage Temperatures ◽

Maximum Population Density

Smoked salmon can be contaminated with Listeria monocytogenes. It is important to identify the factors that are capable of controlling the growth of L. monocytogenes in smoked salmon so that control measures can be developed. The objective of this study was to determine the effect of salt, a smoke compound, storage temperature, and their interactions on L. monocytogenes in simulated smoked salmon. A six-strain mixture of L. monocytogenes (102 to 103 CFU/g) was inoculated into minced, cooked salmon containing 0 to 10% NaCl and 0 to 0.4% liquid smoke (0 to 34 ppm of phenol), and the samples were stored at temperatures from 0 to 25°C. Lag-phase duration (LPD; hour), growth rate (GR; log CFU per hour), and maximum population density (MPD; log CFU per gram) of L. monocytogenes in salmon, as affected by the concentrations of salt and phenol, storage temperature, and their interactions, were analyzed. Results showed that L. monocytogenes was able to grow in salmon containing the concentrations of salt and phenol commonly found in smoked salmon at the prevailing storage temperatures. The growth of L. monocytogenes was affected significantly (P < 0.05) by salt, phenol, storage temperature, and their interactions. As expected, higher concentrations of salt or lower storage temperatures extended the LPD and reduced the GR. Higher concentrations of phenol extended the LPD of L. monocytogenes, particularly at lower storage temperatures. However, its effect on reducing the GR of L. monocytogenes was observed only at higher salt concentrations (>6%) at refrigerated and mild abuse temperatures (<10°C). The MPD, which generally reached 7 to 8 log CFU/g in salmon that supported L. monocytogenes growth, was not affected by the salt, phenol, and storage temperature. Two models were developed to describe the LPD and GR of L. monocytogenes in salmon containing 0 to 8% salt, 0 to 34 ppm of phenol, and storage temperatures of 4 to 25°C. The data and models obtained from this study would be useful for estimating the behavior of L. monocytogenes in smoked salmon.

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Bacterial surface, biofilm and virulence properties of Listeria monocytogenes strains isolated from smoked salmon and fish food contact surfaces

Food Bioscience ◽

10.1016/j.fbio.2021.101021 ◽

2021 ◽

pp. 101021

Author(s):

Mert Sudagidan ◽

Veli Cengiz Ozalp ◽

Orhan Öztürk ◽

Mediha Nur Zafer Yurt ◽

Orhan Yavuz ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Fish Food ◽

Bacterial Surface ◽

Food Contact ◽

Food Contact Surfaces ◽

Smoked Salmon ◽

Contact Surfaces ◽

Virulence Properties

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Listeria in Seafoods: A Review

Journal of Food Protection ◽

10.4315/0362-028x-55.12.1009 ◽

1992 ◽

Vol 55 (12) ◽

pp. 1009-1015 ◽

Cited By ~ 56

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.

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