Evaluation the Microbial Spoilage of Atlantic Salmon (Salmo salar) Fillets during the Packaging Processes and Its Control by Preservatives

Abstract

Seafood consumption is becoming increasingly popular due to the presence of high quality proteins, polyunsaturated fatty acids, and vitamins. Microbial fish spoilage is an area of global concern as it has been estimated that as much as 25% of all fish produced is lost post-harvest owing to microbial activity. This study examined the dynamics of microbial growth in fresh chilled Atlantic salmon (Salmo salar) packed in a modified atmosphere. Atlantic salmon were imported, handled, transported, and processed under optimal conditions. In the present work ten fillet ( not smoked ) and smoked fish samples were brought out from three different industrial steps in the Egyptian company for smoked salmon, El-Obour industrial area, Qalyubia Governorate, Egypt. The bacterial load (Total aerobic bacterial count) of these samples was determined as 4x104 and 3x103 cfu/gm for fillet and smoked samples respectively, this indicate that, all the investigated samples are in the acceptable range one million CFU for fillet and one hundred sousand CFU for smoked according to international standards ISO 4833/2003. Isolation of the contaminant microbiota results in obtaining of two different bacterial species Bacillus cereus /thuringiensis and Citrobacter freundii which identified by morphological and biochemical methods. To control the growth of these bacteria, various water plant extracts of different plant parts were assayed against these bacteria. Among the tested plant extracts, only extract of rosemary (Rosmarinus officinalis) showed strong antibacterial activity against Citrobacter freundii, FIM-SH and Bacillus cereus /thuringiensis, ZF with mean diameter of inhibition zones 16 and 29 mm respectively. These results demonstrate the potential for using plant extracts, especially rosemary extracts, as successful antibacterial agent. These extract could be used extensively as salmon additives in salmon products to reduce or eliminate salmon borne bacterial pathogens and to extend the shelf life of the packaged salmon samples.