Alkali Heat-Treated Quinoa Protein-Tannic Acid Nanoparticles Stabilized Pickering Emulsions: Stability, Dihydroquercetin Delivery and in Vitro Digestion Properties.

Dihydroquercetin, a naturally occurring flavonoid, has limited applications in food systems because of its poor aqueous solubility and low bioaccessibility. A food-grade delivery system was developed to improve the stability and bioaccessibility of dihydroquercetin. Alkali heat treatment was applied to modify the conformational structure and enhance the functional properties of quinoa protein. Covalent quinoa protein-tannic acid nanoparticles were prepared under alkaline conditions and used to stabilize Pickering emulsions for dihydroquercetin encapsulation. The nanoparticles were comprehensively characterized, while the emulsion was evaluated in terms of its microstructure, rheological properties, the stability of encapsulated dihydroquercetin, and in vitro digestion. Optimal nanoparticles at a quinoa protein-tannic acid mass ratio of 10:0.8 exhibited favorable size and emulsifying capacity. Emulsions with 2% (w/v) nanoparticles and an oil phase fraction of 0.7 exhibited enhanced stability and rheology. In vitro digestion revealed that encapsulated dihydroquercetin had 31.31% bioaccessibility, significantly higher than that of free dihydroquercetin (9.34%). This innovative delivery system could expand dihydroquercetin applications in functional foods.