Hake slices stored in retail packages under modified atmospheres with CO2- and O2-enriched gas mixes

This paper presents the examination of the evolution of biochemical, sensory and microbiological changes occurring in hake slices stored in modified atmospheres containing three gas mixes. It also shows how these changes relate to changes in the concentrations of the gas mixes in the tray packs during storage. At the outset of storage, there was a pronounced drop in the level of CO2, associated with lowering of the pH and lower scores for texture in sensory inspection. Nevertheless, by the end of storage, CO2 concentrations had increased. This was associated with growth of Enterobacteriaceae and with more pronounced decreases of O2, which is consumed by these microorganisms. Weight loss was greater in the atmosphere-stored lots, possibly due to the action of CO2. TMA-N and TVB-N began to increase on days 10 and 13 of storage and reached the permitted limits on days 17 and 20. Our analyses revealed no appreciable differences of performance between the different gas mixes, possibly because the gas levels were very similar in the various lots throughout storage.