Different Packaging Conditions to Improve Shelf Life of Filleted Gilt-Head Sea Bream (Sparus aurata)

Abstract

Shelf life of cultured gilt-head sea bream fillets (Sparus aurata) in over-wrap, vacuum and gas mixture packages stored during 27 days at 1±1°C was compared. The gas mixtures used contained CO2, O2, and N2 at different percentages (0% O2 + 50% CO2 + 50% N2; 10% O2 +50%CO2 +40%N2;20%O2 +50%CO2 +30%N2;30%O2 +50% CO2 + 20% N2). The evolution of the freshness degree of the packaged fillets was carried out by measurements of total volatile bases (TVB), trimethylamine (TMA), Tiobarbituric Acid Reactives Substances (TBARS), K i and H values, psychrotrophic bacterial counts and sensory evaluation (color, odor, flavor). Fish fillets were obtained 3 hours after harvesting with the best handling practices. As a consequence of this, the initial bacterial load was very low. The inhibitory effect of CO2 on bacterial growth was very effective, keeping very low counts throughout all the storage period. Gas packages without O2 and vacuum packages presented very low oxidation, whereas TBARS values in over-wrap and 10%, 20% and 30% O2packaged fillets increased according to the oxygen content in the package. Ki value and specially H value differentiated very well among aero-bically stored fillets, vacuum and modified atmosphere packaging. TVB and TMA productions were poor freshness indicators, since no differences were found among treatments. Sensory quality of fillets deteriorated faster in over-wrap than in vacuum and gas packages. Modified atmospheres containing 20 and 30% O2 were given lower sensory scores than vacuum packages, since they gave rise to yellowness of the fillets and off-odors and off-flavors. In summary, modified atmosphere packaging of filleted gilt-head sea breams with a gas mixture consisted of 50% CO2 + 50% N2 gave rise to an important extension of shelf life compared to over-wrap packaging, vacuum and modified atmosphere packaging with gas mixtures containing O2. This was due to the very low oxidation levels produced during the storage, the lower H value as a consequence of a minor production of Hx and the great inhibition on microbial growth.