Interfacial properties of oleosins and phospholipids from rapeseed for the stability of oil bodies in aqueous medium

Oleosins are plant proteins associated with phospholipids in seed oil bodies. The ability of oleosins to aid in the emulsification and stabilization of oil bodies is well known, but little information is available on their interaction with phospholipids at the interface between oil bodies and aqueous medium. Oil body reconstitution at various phospholipid/oleosin ratios was carried out to observe how rapeseed oleosins of 20 kDa and rapeseed phospholipids affect oil body stability. Phospholipids are needed to stabilize oil droplets, but oleosins are mandatory to avoid coalescence. We thus characterized how phospholipids affect the interfacial properties of oleosins at pHs 5.5 and 8.5, by analyzing the adsorption kinetics and interfacial dilational rheology. We observed a synergic effect between oleosins and phospholipids in increasing surface pressure at both pHs. This kind of effect was also observed for the dilational modulus at pH 5.5. A thermodynamic approach highlights these synergic interactions between oleosins and phospholipids through a positive deviation from ideality.