Impact of microfluidization and thermal treatment on the structure, stability and in vitro digestion of curcumin loaded zein-propylene glycol alginate complex nanoparticles

The aim of this study was to modulate the physicochemical properties, molecular interactions and microstructure of zein-propylene glycol alginate (PGA) complex nanoparticles for delivery of curcumin with the aid of high pressure microfluidization (HPM) (50–150 MPa) and thermal treatment (45–85 °C). The size of zein-PGA complex nanoparticles was decreased to around 300 nm. It was confirmed that the pressure of 100 MPa and temperature of 75 °C were the optimum parameters to provide a better protection of entrapped curcumin against environmental stresses. The electrostatic interaction, hydrogen bonding and hydrophobic attraction were the dominant driving forces in the formation of the complex nanoparticles. Field emission scanning electron microscopy (FE-SEM) revealed that HPM and thermal treatment facilitated the complex nanoparticles to form a more uniform size and spherical shape. During in vitro gastrointestinal digestion, zein-PGA complex nanoparticles showed excellent gastric stability and sustained-release of curcumin in the small intestine. HPM and thermal treatment showed a synergistic effect on enhancing the bioaccessibility of curcumin entrapped in zein-PGA complex nanoparticles. The findings revealed the influence of HPM and thermal treatment on functional attributes of the complex nanoparticles, which could be utilized to design food grade nanoparticles with desirable stability and digestive properties.