Preparation and in vitro evaluation of calcium-induced soy protein isolate nanoparticles and their formation mechanism study

► Ca2+ induced SPI nanoparticles (28-179 nm) were prepared at ambient temperature. ► Nanoparticle features can be modulated by adjusting Ca2+ concentration and pH value. ► Ca2+ facilitated formation of SPI aggregates stabilised by hydrogen bonding. ► SPI aggregates were associated to form nanoparticles via hydrophobic interactions. ► These nanoparticles were non-toxic, could be uptaken efficiently into Caco-2 cells.