Evaluation of the microbiological safety and sensory quality of rainbow trout (Oncorhynchus mykiss) processed by the sous vide method Original Research Article

This work evaluates the microbiological quality and sensorial characteristics of rainbow trout processed by the sous vide method under different time/temperature conditions and stored at 2°C and 10°C. The equivalent heat treatments applied in core were: 3.3 min at 90°C (PV70 in core 331.64), 1.04 min at 90°C (PV70 in core 104.5) and 5.18 min at 70°C (PV70 in core 5.18). The product stored at 2°C or 10°C was periodically evaluated to investigate its sensory quality, microbiological condition and proximate composition. The batches stored at 2°C had lower growth counts of mesophiles and psychrotrophs. Moreover, these counts decreased by increasing the heating temperature and time. Staphylococcus aureus, Bacillus cereus, Clostridium perfringens and Listeria monocytogenes were not found in any of the samples. Neither aerobic nor anaerobic spores were detected in the trout samples processed at 90°C for 3.3 min in core and stored at 2°C after 45 days. A heat treatment of 90°C for 3.3 min in core was the most effective to extend the shelf-life of trout (>45 days). Therefore, it can be concluded that the treatment at 90°C for 3.3 min in core is the most effective to ensure the safety and extend the shelf-life of sous vide trout preserving its sensory characteristics. This study establishes the microbiological quality of sous vide trout and emphasizes the relevance of the microbiological quality of the raw materials, heat treatment and storage temperature to ensure the safety of the product, since this fatty fish is not eviscerated and high counts can be found in the raw fish.