Pickering emulsion gel stabilized by pea protein nanoparticle induced by heat-assisted pH-shifting for curcumin delivery

Pickering emulsion gels stabilized by food-grade particles have drawn growing attention in diverse fields. Herein, heat-assisted pH-shifting (HP) was introduced to prepare pea protein nanoparticles (PNPs) by pea protein isolate, and oil-in-water Pickering emulsion gel stabilized by PNPs were fabricated. The structure and interfacial properties of PNPs, microstructure, microrheological properties, digestibility and curcumin bioavailability of PNPs-emulsion gel were investigated. When pH-shifting temperature was increased from 25 (PPI12-25) to 85 °C (PPI12-85), more hydrophobic groups were exposed, with increasing of molecular flexibility and decreasing of three-phase contact angle. PPI12-70 had the lowest interfacial tension. Microscopy measurements proved that PNPs could adsorb to droplets surfaces, forming 3D networks in surrounding aqueous phase. Emulsion gels stabilized by PPI12-70 exhibited stronger gel network, higher crosslinking density, curcumin bioaccessibility and stability. Our results show that HP treatment provides a theoretical basis for fabricating a prospective delivery system for improving bioavailability of hydrophobic nutraceuticals.