Quality Changes during Refrigerated Storage of MA-Packaged Pre-rigor Fillets of Farmed Atlantic Cod (Gadus morhua L.) Using Traditional MAP, CO(2) Emitter, and Vacuum

Summary

Quality changes during 3 wk of refrigerated storage (1.3 degrees C) were studied on pre-rigor filleted farmed Atlantic cod packed in modified atmosphere (MAP, 60% CO(2) and 40% O(2)) or vacuum. The packages of MAP contained either a CO(2) emitter and low gas volume to product volume (g/p ratio) of 1.3, or a 3.9 g/p ratio and no emitter. The CO(2) level remained stable or increased in the packages with CO(2) emitter, whereas the CO(2) level in the packages with no CO(2) emitter decreased to 40% after 4 d of refrigerated storage. High levels of oxygen in the gas mixture prevented formation of trimethyl amine (TMA) during storage of the MA-packed fish, whereas the TMA content increased significantly after 10-d storage in vacuum. MA-packed samples had the highest values of 1-penten-3-ol. Sensory scores of sour, sulfur, and pungent odors were significantly higher for vacuum-packed cod compared to the 2 MA-packaging methods measured 14 d after slaughtering. No differences in sensory scores were observed between the 2 methods of MAP, and shelf life of these samples seemed to be 14 to 21 d. Cod samples packaged in vacuum packages had higher pH values compared to ordinary MAP and packages containing a CO(2) emitter. Bacterial growth was inhibited by MAP and resulted at the end of the storage period in dominance of Carnobacterium and some Photobacterium. In MA packages with high O(2) levels the Photobacterium was inhibited. It is concluded that CO(2) emitters are well suited for reduction of transport volume for MA-packaged farmed cod.