The impact of supercritical carbon dioxide processing on the aroma and physicochemical properties of soybean flour

Soybeans are rich in protein but have limited food applications due to their undesirable volatile compounds, negatively affecting their flavor and consumer acceptance. This study aimed to extract lipids and volatile compounds from soybean flour using supercritical carbon dioxide (SCCO₂) and investigate the impact of extraction conditions on the properties of soybean flour, including particle size distribution, composition, color, and rheological and textural qualities. Similar lipid extraction yields (∼20 %) were obtained with SCCO₂ and conventional hexane extractions. The volatile compound concentration of the soybean flour was reduced after SCCO₂ extraction (0.63–1.00 µg/g) as compared to hexane extraction (1.44–1.68 µg/g). The results showed that SCCO₂-treated soybean flour showed smaller particle sizes (<250 µm, ∼70 %), improved protein purity upon protein extraction, and brighter color as compared to hexane-extracted flour. Additionally, in comparison to untreated soybean flour, SEM images revealed a more disrupted and rough structure in defatted soybean flour. Overall, the presented SCCO₂ approach can improve the aroma of soybean flour while achieving similar lipid extraction yields with conventional hexane extraction, all without the use of toxic organic solvents.