Rancidity development in frozen pelagic fish: influence of slurry ice as preliminary chilling treatment

The slurryice technology has shown profitable advantages when employed instead of traditional flake ice for the manufacture of chilled aquatic species. The present work is aimed at evaluating the effect of slurryice as a preliminarytreatment prior to frozen storage. For it, specimens of a small pelagic fatty fish species (sardine; Sardina pilchardus) were stored in slurryice for 2, 5 and 9 days, then subjected to freezing (–80 °C; 24 h) and finally kept frozen (−20 °C) during 1, 2 and 4 months. At such times, ranciditydevelopment in frozen sardine was measured by sensory (odour, skin, colour and flesh appearance) and biochemical (lipid hydrolysis and oxidation) analyses and compared to a control batch previously chilled in flake ice. Sensory analysis indicated an extended shelf-life time for frozen sardine that was preliminary stored under slurryice for 2, 5 or 9 days, as compared to their counterparts subjected to flake icing. Sensory results were corroborated (P<0.05) by biochemical lipid oxidation indices (thiobarbituric acid reactive substances and the fluorescence formation). The present work opens the way to the use of slurryice instead of flake ice as preliminarytreatment of fish material prior to the frozen storage.