Preparation, encapsulation and protection of quercetin loaded in Pickering gel-like emulsions stabilized by soy protein hydrolysate microgel particles

Pickering gel-like emulsions containing a 50 wt% oil phase were prepared using different soy protein hydrolysate microgel (SPHM) particles synthesized at various pHs (3, 5, 7, and 9) and ultrasonication (300 W, 5 min). Storage stability and cryo-scanning electron microscopy analyses showed the SPHM at pH 7 (SPHM _{pH 7}) particle stabilized gel-like emulsion was stable via closely spaced droplet structures, contained smaller droplets and exhibited stronger electrostatic repulsion between the droplets within 21 days of 4 ℃ storage, with a higher thermodynamic stability and viscoelasticity, as proved by the differential scanning calorimetry (DSC) and rheology properties results. Subsequently, the SPHM _{pH 7} gel-like emulsion was chosen to delivery quercetin, then its environmental stability and digestive properties in vitro were further evaluated. The results showed quercetin-loaded emulsion gel demonstrated higher stability and encapsulation efficiency (EE) of quercetin at pH 5 and 0.2 M NaCl was used, while the heating and freeze–thawing treatments caused the aggregation of oil droplets and instability of emulsions. In vitro digestion revealed the encapsulation of gel-like emulsion accelerated the release of free fatty acids and improved bioaccessibility by approximately 120 % compared with quercetin dispersed in bulk oil. This study indicate that SPHM-stabilized gel-like emulsions could be potential delivery systems for hydrophobic bioactives.