Environmental prevalence and persistence of Listeria monocytogenes in cold-smoked trout processing plants

Abstract

The presence of Listeria monocytogenes on the surfaces of equipment and worker’s hands during different production stages, as well as on fish skin and meat during processing and storage of cold-smoked trout, was investigated. Listeria monocytogenes was recovered from 10 (6.06%) of a total 165 cotton-swabbed samples collected from the surfaces of equipment and worker’s hands at two separate processing facilities. Of 105 samples collected from fish skin and meat during various production steps in both processing plants, 14 (13.33%) were confirmed culture-positive for L. monocytogenes, with recovery being most frequently in samples collected in the area before vacuum packaging. Recovery rates at two different Serbian processing plants did not differ (p<0.05), but suggested that different L. monocytogenes serotypes appeared to be resident within each processing plant and may have contributed to the final product contamination. From all smoked trout samples collected during 7, 14, 21 and 28 days of storage at 4ºC only two were culture-positive for L. monocytogenes serotype 1/2a and both of these were collected on the 7th day of storage. Conversely, 4, 3 and 1 sample(s) were contaminated with L. monocytogenes serotypes 1/2a and 1/2b after 7, 14 and 21 days storage at 10ºC. Listeria monocytogenes was not recovered from smoked trout stored 28 days at 10ºC. Results emphasize the importance of adhering to strict hygienic and quality control standards throughout the processing environment

Evaluation of Three Swabbing Devices for Detection of Listeria monocytogenes on Different Types of Food Contact Surfaces

“…[ 27 ] and Dimitrijevíc et al . [ 14 ] have been demonstrating that the prevalence of L. monocytogenes in the environment of cold-smoked trout processing plants ranges from 6.06%–30%. Moreover, Kovačević et al .…”

“…However, the ability of this bacterium to survive and grow under anaerobic conditions as well refrigerator temperatures, and its high tolerance to salt, allows it to thrive in food processing environments [ 11 , 12 ]. Especially in meat, dairy and seafood processing plants is L. monocytogenes commonly isolated from the food processing environment where it can exist in biofilms [ 9 , 10 , 13 , 14 , 15 ]. These biofilms can occur on food handling or food processing surfaces (e.g., cutting boards, slicing blades, conveyer belts and stainless steel equipment) or in food processing or storage areas (e.g., drains, ventilation, floors, refrigerators) [ 9 , 13 , 16 ].…”

“…The presence of biofilms in food manufacturing and processing facilities can lead to contamination of food products placed on these contaminated surfaces or handled in contaminated areas [ 9 , 17 ]. Moreover, it was suggested that L. monocytogenes strains sequestered within biofilms associated with uneven food contact surfaces may be the most important factor for product contamination [ 14 ]. The environment in which foods are prepared or handled can thus have a significant impact on the microbiological safety of food products.…”

Implementation of Statistical Tools To Support Identification and Management of Persistent Listeria monocytogenes Contamination in Smoked Fish Processing Plants

“…Avoidance of postprocessing contamination requires effective employee training programs, prerequisite programs, sanitation standard operating procedures, and appropriate environmental monitoring programs. Persis tence of L. monocytogenes in food processing environments for months or years has been identified as one of the most important sources of L. monocytogenes cross-contamination of finished products (4,10,30). Because L. monocytogenes strains can persist in food production plants for multiple years (2 4 ,3 3 , 3 7 ,3 9^fl, 48), active strategies such as " seek & destroy" (6) are necessary to control persistent L. monocytogenes.…”

Evaluation of the food safety management system in a hospital food service operation toward Listeria monocytogenes

“…Samples have been taken from incoming (raw) materials, meal components and final products as well from the environment, because environmental sources may, under conditions of poor cleaning and sanitation, harbor pathogenic micro-organisms such as L. monocytogenes or serve as vehicles for cross-contamination (Lianou & Sofos, 2007). Especially, non-food contact surfaces, such as floor drains and cold floors, have a higher prevalence of L. monocytogenes in comparison with food contact surfaces such as slicers and utensils (Carpentier & Cerf, 2011;Dimitrijevíc et al, 2011;Hoelzer et al, 2011). In this case study, the pathogen was not found in the environmental samples.…”