A challenge test on spp. as spoiling microorganism in fish fillets.

Fish fillets are highly susceptible to spoilage, with spp. bacteria being among the main culprits. To maintain products' quality and safety, it is important to control the load of these microorganisms and understand their growth potential in fish fillets. However, setting up challenge tests might be hard due to the difficulty of differentiating intentionally inoculated bacteria from those already present on the fillets. To overcome this obstacle, a pilot study using , a clinically significant bacterial species that is rare in food, was conducted. Vacuum-packed Northern cod, salmon, and plaice fish fillets were experimentally inoculated and subjected to trials at both refrigeration (4 °C) and thermal abuse temperatures (from +4 °C to +6 °C and then to +8 °C). The results showed that the growth potential of in all the fish fillets was less than 0.5 Log CFU/g. This confirms that vacuum packaging could reduce the multiplication of spp. in the fish fillets and underlines as it is crucial to have fish fillets containing initial loads of between 10-10 CFU/g or lower at the beginning of the shelf life in order to control the deterioration rate of the product. This study provides a basis for developing further challenge tests for spp. in the fish industry and highlights the importance of controlling initial loads of to prevent product deterioration during the shelf life.