Quality loss of two gadiform fish species (blue whiting, Micromesistius poutassou; hake, Merluccius merluccius) during frozen storage (-30 and -10 7C; up to 12 months) was studied. For this, hydrolytic (formation of free fatty acids, FFA) and oxidative (conjugated dienes, peroxide and interaction compound formation) lipid damage were analysed. For both species, individual fishes captured in two different trials (May and November) were considered. Increasing (p ,0.05) lipid hydrolysis and oxidation (peroxide and interaction compound formation) were observed for all kinds of samples throughout the frozen storage. Interaction compound detection by fluorescence analysis showed the best correlation values with storage time. Some higher (p ,0.05) hydrolysis development could be observed in hake captured in May than in its counterpart from the November trial, while frozen blue whiting did not provide definite differences for FFA formation between both trials. Concerning peroxide formation, higher (p ,0.05) values were obtained for individual blue whiting and hake captured in November when compared to their corresponding May fish for both frozen storage conditions. Interaction compound formation was also found to be higher (p ,0.05) for November hake fish than for its counterpart captured in May, while blue whiting did not provide definite differences between trials.

The aim of the present study was to comparatively evaluate the effect of different kinds of icing systems employed for the slaughtering and post-mortem storage of cultured turbot (Psetta maxima) on lipid damage (hydrolysis and oxidation). Slurry ice (SI) alone or in presence of ozone (OSI) was applied and compared to the traditional flake ice (FI) treatment. K value and trimethylamine (TMA) formation were also assessed. Some negative effects of ozone presence could be observed on primary and secondary lipid oxidation development; however, oxidation values reached by individuals kept under OSI condition could not be considered high and did not lead to polyunsaturated fatty acid content losses; while ozone presence provided a slowing down of TMA formation. When compared to FI conditions, the employment of SI was found useful to inhibit quality losses (K value and TMA formation), while no differences in lipid hydrolysis or oxidation development could be observed.

El objetivo de este estudio fue evaluar el efecto que sobre la alteración lipídica (hidrólisis y oxidación) tiene el empleo de distintos tipos de hielo durante las etapas de sacrificio y refrigeración de rodaballo (Psetta maxima) cultivado. Se aplicó hielo líquido (SI) solo, o en combinación con ozono (OSI) y se comparó con hielo tradicional en escamas (FI). También se realizaron las medidas de valor K y contenido en trimetilamina (TMA). Se observó un pequeño efecto negativo del ozono sobre las oxidaciones primaria y secundaria, siendo considerados bajos los valores obtenidos y sin efecto sobre el contenido en ácidos poliinsaturados; asimismo, la presencia de ozono produjo un descenso en la formación de TMA. Al comparar el pescado de los tratamientos SI y FI, el primero reflejó menores pérdidas de calidad (valor K y TMA), al tiempo que no se pudo observar efecto diferencial sobre la oxidación e hidrólisis lipídicas