Microbiological and quality indices for safety and shelf-life prediction of mild processed fresh fish stored under ice and in abuse conditions

Consumers consumption of fish products as well as fish farming and retailing of fresh products is increasing mainly due to their nutritional value. On the other hand, the actual European food code does not give indications on analytical parameters to establish the safety and quality of mild processed fish fresh products. The aim of this work was to verify the presence of pathogens and suggest possible shelf-life indices for three types of fish, imported into Italy under freeze conditions, sold after being gutted and sliced into 100g-portions. Samples of Sparus aurata, Dicentrarchus labrax and Salmo salar were collected in a production plant and stored under ice and in abuse condition (6°C). Microbial analysis revealed the absence of the most frequently occurring pathogens such as Listeria monocytogenes, Aeromonas hydrophila, Vibrio parahaemolyticus. The complete absence of Enterobacteriaceae at the beginning and during storage could be attributable to the frequent practice of treating fish with antibiotics during farming. The growth dynamics of total mesophylic bacteria, Pseudomonadaceae and sulfite producing bacteria (mainly Shewanella putrefaciens) indicated that the generation time was influenced by both the type of fish and the storage temperature. Pseudomonadaceae could be indicated as the specific spoilage group for all the three fish species. Also biogenic amines and trimethylamine analyses during storage as well as correlations between bacterial growth and sensory analysis parameters showed to be significant indicators to predict the shelf-life of the products also in relation to the storage temperature.