Oxidative stabilization of ultra-high omega-3 concentrates as ethyl esters or triacylglycerols

A comparative study of the oxidative stability of “ultra-high” ω3 concentrates (80%) from fish oils as triacylglycerols (TAG) or ethyl esters (EE), as well as their stabilization by supercritical extracts of rosemary (SER), α-tocopherol or their mixture, by Rancimat method and throughout storage time, was carried out. No significant differences were found between EE and TAG on oxidative stability when measured by Rancimat conditions in the range of 50−90 °C. However, storage experiments revealed a poor stability of the EE concentrate form, measured by the monitorization of peroxide and p-anisidine values. Concerning the stabilization by antioxidants, there was a lack of antioxidant effect of evaluated compounds when Rancimat assays were performed at 70 °C, whereas an antioxidant effect began to evidence at 60 °C, and a clearest antioxidant protection was measured at 50 °C for the mixture of the SER plus α-tocopherol in both EE and TAG forms. This selected binary mixture efficiently stabilized the ω3-TAG concentrate throughout 50 days of storage conditions, whereas the stabilization of ω3-EE concentrate was worse. Therefore, the combination of SER and α-tocopherol seemed to be a good antioxidant mixture for the efficient stabilization of extremely labile ultra-high ω3 concentrates, especially in the form of ω3 TAG oils.

► Oxidative stability of ultra-high ω3 oils as triacylglycerol (TAG) or ethyl ester (EE) ► No significant differences between EE and TAG by Rancimat conditions at 50−90 °C ► Worse stability of EE at storage conditions by peroxide and p-anisidine values ► Mixture rosemary extract/tocopherol at 50 °C-Rancimat test selected for stabilization ► Stabilization of oils by the binary mixture confirmed at normal storage conditions