SHELF-LIFE OF MODIFIED-ATMOSPHERE-PACKAGED FRESH TILAPIA FILLETS STORED UNDER REFRIGERATION AND TEMPERATURE-ABUSE CONDITIONS

We investigated the shelf life of fresh Tilapia spp. fillets packaged in high-barrier film under both 100% air and a modified atmosphere (MA ) of 75% CO2:25% N-2, and stored under refrigeration (4 degrees C) and abuse temperatures (8 and 16 degrees C). The chemical spoilage indica tors trimethylamine, K-value, and surface pH, as well as microbial cou nts, were compared with the sensory characteristics of spoilage. For f illets packaged under 100% air, the shelf life was 9 to 13 days at a s torage temperature of 4 degrees C, but decreased to 3 to 6 days at 16 degrees C. However, the shelf life of MA-packaged fillets stored at 4 degrees C increased to >25 days when the lag phase and generation time of the bacteria were extended. MA-packaged fillets stored under tempe rature-abuse conditions (8 and 16 degrees C) had a shorter shelf life. The trimethylamine content associated with onset of sensory spoilage for MA-packaged fillets increased as storage temperature increased and differed for each temperature. The surface pH and K-values of MA-pack aged fillets were not good indicators of spoilage onset.