Effect of Alkaline pH Extraction on the Stability and Digestive Properties of Soybean Oil Bodies

The purpose of this study was to understand the stability of natural emulsions formed from soybean oil bodies (SOB) extracted at alkaline pH (8.0‒11.0) and their digestive properties in the gastrointestinal tract. The stability of SOB was evaluated in terms of its basic composition, particle size, zeta potential and rheology, and the digestive properties were evaluated in terms of fatty acid release from SOB and the microstructure of SOB. The results showed that with an increase in extraction pH, the water and protein contents of SOB decreased and the particle size decreased from (471.57 ± 8.53) nm to (424.77 ± 12.21) nm, while the lipid content increased. In addition, the oxidative stability of SOB showed a similar trend. Specifically, the peroxide value (POV) decreased with increasing extraction pH and the thiobarbituric acid reactive substances (TBARS) value increased with an increase in storage time. The apparent viscosity decreased with increasing shear rate. SOB emulsions showed shear thinning behavior with G’ being greater than G” for all samples, and the release percentage of free fatty acids from SOB significantly increased with increasing extraction pH (P < 0.05). This study provides theoretical support for the wide application of highly stable natural SOB.