SHELF-LIFE AND TOXIN DEVELOPMENT BY CLOSTRIDIUM-BOTULINUM DURING STORAGE OF MODIFIED-ATMOSPHERE-PACKAGED FRESH AQUACULTURED SALMON FILLETS

Shelf Life (onset of sensory spoilage) and the potential for toxin pro duction by Clostridium botulinum type E in retail-type packages of fre sh aquacultured salmon fillets packaged in high-barrier film bags unde r selected atmospheres (100% air, a modified atmosphere containing 75% CO2:25% N-2, and vacuum) and stored under refrigeration (4 degrees C) and temperature-abuse conditions (8 and 16 degrees C) were investigat ed. Chemical spoilage indicators (trimethylamine and surface pH) and m icrobial populations were compared with sensory spoilage characteristi cs. Storage temperature influenced the time to onset of both sensory s poilage and toxin development in salmon fillets packaged in all atmosp heres. The shelf Life of fillets packaged in all atmospheres decreased with increase of storage temperature from 4 to 16 degrees C. Trimethy lamine content associated with the onset of spoilage for 100% air-pack aged fillets increased as storage temperature increased. However, for modified-atmosphere-packaged fillets, the trimethylamine content assoc iated with the onset of spoilage increased as storage temperature decr eased from 8 to 4 degrees C. Surface pH was not a good spoilage indica tor for modified-atmosphere-packaged fillets. Toxin development preced ed sensory spoilage at 16 degrees C storage for fillets packaged in mo dified atmospheres, Toxin development coincided with sensory spoilage or was slightly delayed for the fillets packaged in all the atmosphere s at 8 degrees C storage. At 4 degrees C none of the fillets packaged in either of the atmospheres developed toxin, even 20 days after spoil age as determined by sensory characteristics.