Plant oleosomes: new strategy for stable oil-in-water emulsions

Abstract: Emulsions are mostly prepared with oil extracted from oil seeds, emulsified by adding emulsifiers and protected against oxidation with antioxidants. But actually, in seed cells the oil is naturally stored in emulsion like droplets called oleosomes. Oleosomes consist of a core of triglycerides stabilized by phospholipids and proteins, and packed with antioxidants. During classical processing, these natural droplets are destroyed; the native emulsifiers (proteins and phospholipids) are separated from the oil and large parts of the antioxidants are removed by refining the oil. This is in many ways a paradox and raises the question: why not directly use the naturally occurring oleosomes in emulsions?

The suitability of rapeseed oleosomes as emulsions was tested, by comparing their oxidative and physical stability to emulsions made with crude or refined rapeseed oil stabilized by rapeseed lecithin. Emulsions were prepared with 10 % oil and stored under accelerated conditions at 40 °C for 63 days. ¹H Nuclear Magnetic Resonance (¹H NMR) revealed that in oleosome emulsions, ~40 % less lipid hydroperoxides (25 mmol/kg triglycerides) were formed compared to lecithin stabilized emulsions (40-45 mmol/kg triglycerides). Oleosomes were also physically stable during the 63 days of storage. No coalescence was observed with microscopy and light scattering. Our finding suggest that, using oleosomes directly is a promising way for making stable oil-in-water emulsions.