Impact of phosphatidylcholine and galactolipids on the oxidative stability of commercial microalgal oil containing tocopherols.

This study investigates the impact of monogalactosyldiacylglycerol (MGDG), and digalactosyldiacylglycerol (DGDG) on the oxidative stability of commercial microalgal oil in comparison to phosphatidylcholine (PC). MGDG, DGDG, and PC were added at concentrations below or above their critical micelle concentration (CMC) in commercial microalgal oil spiked or not with an additional 1000 μM α-tocopherol. Samples were stored at 40 °C for shelf-life test and their oxidative stability was assessed by nuclear magnetic resonance (NMR) spectroscopy. At concentrations below CMC (i.e., 25 μM), PC acted as an antioxidant partly due to its metal chelation ability. At concentrations above CMC (i.e., 300 μM), reverse micelles formed by PC and MGDG enhanced the oxidative stability of the oil, while additional tocopherols reduced this antioxidant effect. DGDG exhibited an antioxidant effect only at later oxidation stages. In conclusion, incorporating polar lipids such as PC, MGDG and DGDG in combination with tocopherols can help improve the shelf life of bulk oils.