Modelling the Effect of Osmotic Pre-treatment with Alternative Solutes on the Shelf Life of Gilthead Seabream Fillets during Refrigerated and Super-chilled Storage

摘要

The objective of the study was the kinetic modelling of the shelf life of osmotically pre-treated fish during super-chilled storage. Fresh gilthead seabream (Sparus aurata) fillets were pre-treated for 0 to 360 min at 15°C, in osmotic solution 50% maltodextrin (DE47) and 5% NaCl. Water loss, solid gain, salt content and water activity were monitored throughout pre-treatment. Slices, untreated (coded as Control) and pre-treated for 45 min (coded as HDM), were aerobically packed and stored isothermally at -3, -1, 0, 2.5, 5, 10 and 15°C. For samples stored at -3, -1 and 2.5°C, two alternative solutions 40% HDM (DE 47), 10% trehalose, 5% NaCl (coded as HDM-treh) and 40% HDM (DE 47), 10% glucosamine, 5% NaCl (coded as HDM-gluc) were also used. Quality assessment was based on microbial growth (total viable count, Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae sp., H2S-producing bacteria, lactic acid bacteria, yeasts and moulds), total volatile nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), lipid oxidation (TBARS) and sensory scoring. Quality indices were kinetically modelled and temperature dependence of quality loss rates was modelled by Arrhenius equation. Osmotic pre-treatment led to significant shelf-life extension of fillets, in terms of microbial growth and organoleptic deterioration. The pre-treatment with the alternative solutes led to depression of the freezing point (-1.8, -2.6, -3.2 and -3.5°C for the untreated samples and the osmotically pre-treated with HDM, HDM-treh and HDM-gluc, respectively). TVB-N and TMA-N values were higher in untreated samples, followed by osmotically pre-treated fillets. Based on sensory evaluation, the shelf-life was 10, 12, 14 and 15 days at 2.5°C for untreated and pre-treated with HDM, HDM-treh and HDM-gluc, respectively, while the respective values at -1°C were 26, 35, 38 and 46 days.