Shelf-life extension of cod fillets with an acetate buffer spray prior to packaging under modified atmospheres

Fresh cod fillets (gadus morhua) were sprayed with a 10% acetate buffer (pH 5.6), packed with an industrial gas-flushing packaging machine under modif ied atmospheres (50% CO2-45% O-2-5% N-2, 2 cm(3)/1 g gas/product ratio) and stored at 7 degrees C for 12 days. Control cod filets were directly packed and stored under the same conditions. A reduction of the aerobic plate cou nts was observed immediately after the cod fillets had been sprayed. During storage under modified atmospheres, there was complete inhibition of H2S-p roducing bacteria and Enterobacteriaceae in the treated cod fillets. Produc tion of total volatile bases and trimethylamine (TMA) was inhibited in trea ted fillets for 10 days' storage under modified atmospheres. Inhibition of TMA production can be attributed to growth inhibition of H2S-producing bact eria, inhibition of the trimethylamine oxide (TMAO)-dependent metabolism of TMAO-reducing bacteria and the stable pH during storage. The shelf-life, a t 7 degrees C, of treated cod fillets, based on cooked flavour score, was a lmost 12 days, ca 8 days more than self-life of the control fillets.