Fabrication of stable zein nanoparticles coated with soluble soybean polysaccharide for encapsulation of quercetin

The present work aims to prepare and stabilize zein colloidal nanoparticles using soluble soybean polysaccharide (SSPS) as a stabilizer. A simple antisolvent precipitation method was used to fabricate the zein/SSPS composite nanoparticles at pH 4.0. The results showed that the SSPS-stabilized zein nanoparticles (size around 200 nm, PDI below 0.2) did not aggregate or precipitate at pH 2.0–8.0. And they were also relatively stable for elevated ionic strength and high temperature. Affected by the SSPS coating, the surface hydrophobicity of the zein nanoparticles decreased over a wide pH range. Conditions of forming zein/SSPS nanoparticles were successfully used to encapsulate hydrophobic quercetin (Q). The encapsulation efficiency was greatly improved to 82.5% after SSPS coating, compared to 59.2% for the zein without coating. Besides, the photochemical stability and ABTS+ scavenging ability of Q in zein/SSPS composite nanoparticles were significantly enhanced. This study demonstrates that these composite nanoparticles can be used as all-natural delivery systems for bioactive molecules in food and pharmaceutical formulations.