The effect of glazing based on saponin-free quinoa (Chenopodium quinoa) extract on the lipid quality of frozen fatty fish

This study focussed on the rancidity stability of frozen fatty fish. Its basic objective was to investigate the effect of a glazing system including a saponin-free quinoa (Chenopodium quinoa) extract during the frozen storage of Atlantic mackerel (Scomber scombrus). For it, two different concentrations of 80% aq. (v/v) ethanol quinoa extracts (0.45 and 1.36 g lyophilised quinoa L−1 solution, respectively) were tested and compared with two control treatments (water glazing and non-glazing conditions). Chemical and sensory changes were monitored for a 8-month frozen storage. An inhibitory effect (p < 0.05) of the glazing system including the most concentrated saponin-free quinoa extract was observed on the lipid hydrolysis (free fatty acid formation) evolution and on the formation of secondary (thiobarbituric acid reactive substances) and tertiary (fluorescent compounds) lipid oxidation compounds. A sensory quality enhancement and shelf life increase was obtained in fish submitted to glazing conditions including the most concentrated quinoa extract in agreement to raw (gills and muscle odour) and cooked (muscle odour) descriptors. A novel quinoa-glazing system is proposed, this avoiding the inconveniences of the saponin compounds presence.