The oxidative stability of sunflower oleosomes depends on co-extracted phenolics and storage proteins

Unsaturated triacylglycerols (TAGs) are highly oxidatively stable when extracted as part of the natural lipid droplets (oleosomes) from seeds. This study investigates whether this protection is inherent to oleosomes or derives from phenolics (PHE) and storage proteins (PRO), which are commonly co-extracted with oleosomes. Oleosome extracts with low (PHE <0.7 mmol/kg TAGs, PRO <4 wt% on DM) or high (PHE >10 mmol/kg TAGs, PRO >9 wt% on DM) amounts of phenolics and storage proteins were obtained from sunflower seeds and then dispersed to create 10 wt% oil-in-water emulsions at pH 3 that were stored at 40 °C for 120 days. No triacylglycerol oxidation occurred in emulsions with high amounts of phenolics, while a high amount of storage proteins reduced the lipid oxidation rate. Our findings evidence that the oxidative stability of triacylglycerols in oleosomes derives primarily from the co-extracted phenolics and storage proteins and not only from the architecture of oleosomes.