Effect of Brine Freezing on the Rancidity Development during the Frozen Storage of Small Pelagic Fish Species

Brine freezing was applied to two small pelagic underutilised fish species (mackerel, Scomber scombrus; horse mackerel Trachurus trachurus). Rancidity development was studied during their frozen (-18oC) storage up to 9 months and quality change results were compared to common freezing conditions (control treatment). Fish samples treated under brine freezing conditions showed a higher lipid oxidation development (peroxide value and thiobarbituric acid index) and worse marks on some sensory attributes (general aspect, odour and colour) than control fish. However, samples treated under brine freezing conditions provided a lower lipid hydrolysis development (free fatty acid formation) and better scores for consistency. Comparison between both fish species led to a higher secondary lipid oxidation formation (thiobarbituric acid index) for mackerel, while horse mackerel showed to be more prone to interaction compound formation (fluorescence detection); however, both fish species showed the same shelf-life times (3 and 5 months for brine and control freezing conditions, respectively). As a result of brine freezing conditions, an increase in NaCl content in white muscle of both species was observed. According to the results obtained in the present work, brine freezing treatment is not recommended for these two small pelagic fish species. Running Title: Brine freezing of pelagic fish