ENVIRONMENTAL PREVALENCE AND PERSISTENCE OF LISTERIA MONOCYTOGENES IN COLD-SMOKED TROUT PROCESSING PLANTS

The presence of Listeria monocyto genes 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 monocyto genes 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. monocyto genes, 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. monocyto genes 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 4 degrees C only two were culture-positive for L. monocyto genes serotype 1/2a and both of these were collected on the 7(th) day of storage. Conversely, 4, 3 and 1 sample(s) were contaminated with L. monocyto genes serotypes 1/2a and 1/2b after 7, 14 and 21 days storage at 10 degrees C. Listeria monocyto genes was not recovered from smoked trout stored 28 days at 10 degrees C. Results emphasize the importance of adhering to strict hygienic and quality control standards throughout the processing environment.