Understanding the bioaccessibility of lipidic compounds and the formation of free oxylipins of encapsulated omega-3-rich marine oils during in vitro digestion

Supplementation with encapsulated marine oils rich in omega-3 fatty acids is common, but their lipidic compounds’ behavior during digestion is not fully understood. Thus, this study investigated the impact of in vitro digestion (5 min oral, 2 h gastric, and 4 h intestinal digestion) of one encapsulated fish oil and two encapsulated algae oils on the bioaccessibility of lipidic compounds of nutritional interest and the formation of oxidation products (n ≥ 3). Proton nuclear magnetic resonance evidenced a negative linear relationship (r = -0.9957) between the unsaturation degree of the oils’ main components and their bioaccessibility, with the algae oils showing higher bioaccessibility than fish oil. The determination of hydroperoxy-( Z,E )-conjugated-dienes and n-alkanals revealed a similar or lower oxidation level during digestion of the two algae oils, underscoring them as stable sources of long-chain omega-3 fatty acids. Additionally, extensive characterization of oxylipins by liquid chromatography-tandem mass spectrometry revealed a specific profile in each oil, showing, for the first time, eicosapentaenoic acid to be more prone to the formation of these potentially bioactive lipid mediators during digestion, compared to docosahexaenoic acid. Therefore, this study evidenced the impact of omega-3 fatty acid and acyl groups composition on the bioaccessibility of marine lipidic compounds and oxylipins formation, highlighting commercially available algae oils as promising sustainable sources of omega-3 fatty acids. • Encapsulated fish oil (FO) and algae oils (AO1 and AO2) were subjected to in vitro digestion. • Bioaccessibility, higher in algae oils than FO, exhibited a linear inverse correlation with their unsaturation degree. • AO1 displayed a lower oxidation level and tocopherol loss during digestion than FO and AO2. • Algae oils were highlighted as potential sustainable alternative to fish oils. • Eicosapentaenoic acid showed higher susceptibility to form different free oxylipins than docosahexaenoic acid.