الفهرس 
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Abstract
Smoked salmon (Salmo salar) represents a healthy, nutritious food with global distribution and increasing consumption and economic value. Contaminating Listeria monocytogenes in fresh salmon represents a health hazard to consumers, is a major challenge for salmon processors. The evaluation of microbiological quality and safety of ten different brand samples of vacuum-packed cold-smoked salmon, CSS (n=50) from supermarkets of two cities in Egypt, and the changes in the microbiological quality and safety of CSS (Salmo salar) that obtained from one factory located in 10th Ramadan City after their directly production. Where, samples from the factory were stored at 5 and 0°C and then examined after 0, 7, 14, 21, 28 and 35 days of storage. For all samples, microbiological parameters [total bacterial counts (TBC), total lactic acid bacteria (LAB), lactobacilli count, Pseudomonas group and Enterobacteriaceae count] were performed at the same time. Pathogenic microorganisms (Staphylococcus aureus and Listeria spp.) were examined in all samples. These pathogenic bacteria were not detected in all factory samples tested and during the time of storage. The TBC, LAB, lactobacilli count, Pseudomonas group and Enterobacteriaceae family showed a significant increase with storage time and temperature regimes. Shelf lives of smoked salmon stored at 0 and 5 °C were 26 and 8 days, respectively. Lactobacillus spp. and Pseudomonas spp. were dominant in terms of deterioration in quality. Also, this study was conducted to investigate Listeria presence in one cold-smoked salmon (CSS) processing factory, Al-Sharkia Governorate, Egypt as well as to evaluate detection accuracy of Agar Listeria according to, Ottaviani and Agosti (ALOA) using 16S rRNA technique. A total of 50 and 60 samples from final products and their processing line six-point (PLS) have been tested for the occurrence of this bacterium, respectively. The above technique showed that Bacillus safensis, Oceanobacillus picturae and B. wiedmannii have been found in CSS. The presumptive of Listeria spp. (L. monocytogens) in CSS and processing line six-point (PLS)were found to be 8 and 16.67%, respectively while presumptive of Listeria spp. (L. innocua) were 26 and 16.67% respectively. The high occurrence percentage of this pathogen in PLS of factory could be attributed to cross-contamination. As a direct consequence, Listeria spp. control must be implemented through a proper cleaning and sanitation programme as well as a HACCP plan to prevent cross-contamination and spread of these pathogens to final products during the fishery processing. The sliced of cold-smoked salmon (CSS) were coated with different preservative agents (1% sodium lactate + 2 g/L nisin(T1) and 1% acetic acid + 2 g/L chitosan (T2) for controlling the growth of cocktail of Listeria monocytogenes, L. innocua, Escherichia coli, and Pseudomonas aeruginosa as compared to ampicillin and chloramphenicol. In vitro, the two antibacterial agents exhibited antibacterial activities equivalent to or higher than the two antibiotics in the following order: T1 > T2 > T1+T2 > antibiotics, respectively. All tested substances particularly the T1 showed increased concentration-dependent antibacterial and antibiofilm inhibition. The antibiofilm efficiency was in the following descending order: T1 > T2 > T1+T2 and the susceptibility of the bacteria to the antibacterial gadgets were in the following order: L. innocua > L. monocytogenes > P. aeruginosa> E. coli. Appling T1 or T2 to CSS inoculated with the four cocktail bacteria; Listeria (L. monocytogenes+ L. innocua), E. coli, and P. aeruginosa (ca. 4.5 log CFU/mL) could inhibit their propagation after 15–30 days storage at 4 °C. Results revealed that the most effective treatment was T1. Therefore, thus coating with T1 effectively prevented Listeria spp. and other pathogenic bacteria growth and prolonged the shelf life of CSS.