Résumé
To improve the n-3/n-6, the richness of oilseeds in polyunsaturated fatty acids beside their content in proteins, antioxidants arouse strong interest in their use in human diet. Their oxidative stability during processing and storage needs to be assessed. Oleosomes (OB) were prepared by grinding high oleic sunflower, rape or chia seeds in water. After filtration on a cheesecloth and centrifugation, an OB cream, an intermediate aqueous phase and a pellet were collected. The OB cream was redispersed in water to yield 4 wt.% lipids. Upon incubation, O2 consumption in the tubes’ headspace was measured for the different systems. Washed OB suspensions hardly showed O2 consumption, except for the chia OB after day 5. Conversely, extensive O2 consumption occurred rapidly in initial suspensions, showing that these systems are prone to oxidation. Yet, when measuring lipid oxidation markers in all the systems, low levels were found. This suggests that O2 is consumed by other reactions. Proteins can also be targeted by oxidation; therefore, we checked whether the fluorescence of tryptophan was affected in the different samples, but this was not the case. Conversely, other fluorophores were detected most likely corresponding to phenolic compounds – and of which the fluorescence intensity seemed to be somewhat quenched upon incubation. This may indicate that phenolic compounds, present in the full suspensions (and in the aqueous phase + pellet) but largely eliminated in the OB suspensions, substantially oxidize. This is consistent with the visual browning of the samples upon incubation, which looked well aligned with the extent of O2 consumption. These results confirm that OB overall exhibit a good resistance to lipid oxidation, as often claimed in literature, apparently targeting the non-OB constituents of the oilseeds. Further investigations of the exact substrates and reactions involved are ongoing.