Longitudinal study on the sources of Listeria monocytogenes contamination in cold-smoked salmon and its processing environment in Italy

2012 ◽  
Vol 158 (1) ◽  
pp. 79-84 ◽  
Author(s):  
Pierluigi Di Ciccio ◽  
Domenico Meloni ◽  
Anna Rita Festino ◽  
Mauro Conter ◽  
Emanuela Zanardi ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Listeria Monocytogenes ◽  
Smoked Salmon

scholarly journals Microbial survey of ready-to-eat salad ingredients sold at retail reveals the occurrence and the persistence of Listeria monocytogenes Sequence Types 2 and 87 in pre-packed smoked salmon

2017 ◽  
Vol 17 (1) ◽  
Author(s):  
Man Ling Chau ◽  
Kyaw Thu Aung ◽  
Hapuarachchige Chanditha Hapuarachchi ◽  
Pei Sze Valarie Lee ◽  
Pei Ying Lim ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Smoked Salmon ◽  
Sequence Types

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 Inhibition by Whey Protein Films and Coatings Incorporating Lysozyme

2005 ◽  
Vol 68 (11) ◽  
pp. 2317-2325 ◽  
Author(s):  
SEACHEOL MIN ◽  
LINDA J. HARRIS ◽  
JUNG H. HAN ◽  
JOHN M. KROCHTA
Keyword(s):  
Elastic Modulus ◽  
Listeria Monocytogenes ◽  
Whey Protein ◽  
Oxygen Permeability ◽  
Protein Isolate ◽  
Lower Percentage ◽  
Growth Media ◽  
Antimicrobial Effects ◽  
Smoked Salmon ◽  
Yeasts And Molds

The effects of whey protein isolate (WPI) films and coatings incorporating lysozyme (LZ) on the inhibition of Listeria monocytogenes both in and on microbial media, as well as on cold-smoked salmon, were studied. The antimicrobial effects of LZ were examined using various growth media by turbidity and plate counting tests. Disc-covering and disc-surface–spreading tests were also used to evaluate the effects of WPI films incorporating LZ. Smoked salmon was used as a model food to test the antimicrobial effects of WPI coatings incorporating LZ, both initially and during storage at 4 and 10°C for 35 days. Tensile properties (elastic modulus, tensile strength, and percentage of elongation), oxygen permeability, and color (Hunter L, a, and b) of WPI films with and without LZ were also compared. LZ inhibited L. monocytogenes in broth and on agar media. The number of cells surviving after LZ treatments depended on the type of media. WPI films incorporating 204 mg of LZ per g of film (dry basis) inhibited the growth of a preparation of 4.4 log CFU/cm2 L. monocytogenes. WPI coatings prepared with 25 mg of LZ per g of coating solution initially inactivated more than 2.4, 4.5, and 3.0 log CFU/g of L. monocytogenes, total aerobes, and yeasts and molds in smoked salmon samples, respectively. The WPI coatings incorporating LZ efficiently retarded the growth of L. monocytogenes at both 4 and 10°C. The anti–L. monocytogenes effect of LZ-WPI coating was more noticeable when the coating was applied before inoculation than when the coating was applied after inoculation. Significantly higher elastic modulus values and lower percentage of elongation and oxygen permeability values were measured with the WPI films incorporating LZ than with the plain WPI films.

scholarly journals Prevalence and Distribution of Listeria monocytogenes in Three Commercial Tree Fruit Packinghouses

2021 ◽  
Vol 12 ◽  
Author(s):  
Tobin Simonetti ◽  
Kari Peter ◽  
Yi Chen ◽  
Qing Jin ◽  
Guodong Zhang ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Listeria Monocytogenes ◽  
Cold Storage ◽  
Activity Levels ◽  
Early Winter ◽  
Water Drainage ◽  
Critical Areas ◽  
Tree Fruit ◽  
Food Contact Surface ◽  
Multiple Tree

A 2-year longitudinal study of three tree fruit packinghouses was conducted to determine the prevalence and distribution of Listeria monocytogenes. Samples were collected from 40 standardized non-food-contact surface locations six different times over two 11-month production seasons. Of the 1,437 samples collected, the overall prevalence of L. monocytogenes over the course of the study was 17.5%. Overall prevalence did not differ significantly (p > 0.05) between each year. However, values varied significantly (p ≤ 0.05) within each production season following packing activity levels; increasing in the fall, peaking in early winter, and then decreasing through spring. L. monocytogenes was most often found in the packing line areas, where moisture and fruit debris were commonly observed and less often in dry cold storage and packaging areas. Persistent contamination was attributed to the inability of water drainage systems to prevent moisture accumulation on floors and equipment during peak production times and uncontrolled employee and equipment traffic throughout the facility. This is the first multiyear longitudinal surveillance study to compare L. monocytogenes prevalence at standardized sample sites common to multiple tree fruit packinghouses. Recommendations based on our results will help packinghouse operators to identify critical areas for inclusion in their L. monocytogenes environmental monitoring programs.

Modeling and Predicting the Growth of Lactic Acid Bacteria in Lightly Preserved Seafood and Their Inhibiting Effect on Listeria monocytogenes

2007 ◽  
Vol 70 (11) ◽  
pp. 2485-2497 ◽  
Author(s):  
OLE MEJLHOLM ◽  
PAW DALGAARD
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Chemical Characterization ◽  
Effect Of Temperature ◽  
Inhibiting Effect ◽  
Smoked Salmon ◽  
Boundary Model ◽  
Parameter Values ◽  
Separate Product

A cardinal parameter model was developed to predict the effect of diacetate, lactate, CO2, smoke components (phenol), pH, NaCl, temperature, and the interactions between all parameters on the growth of lactic acid bacteria (LAB) in lightly preserved seafood. A product-oriented approach based on careful chemical characterization and growth of bacteria in ready-to-eat seafoods was used to develop this new LAB growth model. Initially, cardinal parameter values for the inhibiting effect of diacetate, lactate, CO2, pH, and NaCl–water activity were determined experimentally for a mixture of LAB isolates or were obtained from the literature. Next, these values and a cardinal parameter model were used to model the effect of temperature (Tmin) and smoke components (Pmax). The cardinal parameter model was fitted to data for growth of LAB (μmax values) in lightly preserved seafood including cold-smoked and marinated products with different concentrations of naturally occurring and added organic acids. Separate product validation studies of the LAB model resulted in average bias and accuracy factor values of 1.2 and 1.5, respectively, for growth of LAB (μmax values) in lightly preserved seafood. Interaction between LAB and Listeria monocytogenes was predicted by combining the developed LAB model and an existing growth and growth boundary model for the pathogen (O. Mejlholm and P. Dalgaard, J. Food Prot. 70:70–84). The performance of the existing L. monocytogenes model was improved by taking into account the effect of microbial interaction with LAB. The observed and predicted maximum population densities of L. monocytogenes in inoculated lightly preserved seafoods were 4.7 and 4.1 log CFU g−1, respectively, whereas for naturally contaminated vacuum-packed cold-smoked salmon the corresponding values were 0.7 and 0.6 log CFU g−1 when a relative lag time of 4.5 was used for the pathogen.

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