Enzyme-Assisted Aqueous Extraction of Oil from Isolated Oleosomes of Soybean Flour

Enzyme-assisted aqueous extraction of oil from isolated soybean oleosomes was evaluated as an alternative to the conventional organic solvent extraction. Three different processes: hydrolysis of oleosomes, thermal demulsification of the skim or the slurry, and destabilization of the cream by the churning butter process were examined to enhance the release of free oil from isolated oleosomes. The oil extraction involved incubating the oleosomes with either 0, 2.5 or 5% protease (Protex 6L^®) at 60 °C, pH 9 for 18 h, destabilizing the slurry by three thermal strategies: freeze/thaw, freeze/thaw and heating, and destabilizing the cream by the churning butter process without and with 5% of phospholipase A₂ (Multifect L1 10L^®), at 40 °C, pH 8 for 4 h. The best total free oil yield was 83–88% by hydrolyzing oleosomes with 2.5 or 5% Protex 6L^®, destabilizing the slurries by heating and destabilizing the resulting cream by the churning butter process. The oleosomes treated with 2.5 and 5% proteases generated hydrolyzed soybean storage proteins at 18–20% degree of hydrolysis, with all the storage proteins hydrolyzed to peptides smaller than 6.5 kDa, compared to the oleosomes disrupted without proteases.