Hydrolyzed rice glutelin nanoparticles as particulate emulsifier for Pickering emulsion: Structure, interfacial properties, and application for encapsulating curcumin

Oil-in-water Pickering emulsions prepared by food-grade particles have gained increasing interest on account of their potential application in the delivery system for lipophilic active compounds. In this project, hydrolyzed rice glutelin (HRG) nanoparticles were successfully fabricated inducing by different concentrations of ethanol. The structure, interfacial properties of HRG nanoparticles, Pickering emulsion stability and in vitro gastrointestinal digestion characteristics were investigated. With ethanol concentration increasing from 25% to 100%, the Z-average diameter and surface activity of HRG nanoparticles increased firstly and then decreased, whereas the magnitudes of the ζ-potential and surface hydrophobicity increased. Quartz crystal microbalance with dissipation (QCM-D) indicated that HRG nanoparticles induced by ethanol with the concentration of 50% (HRG50) and 75% (HRG75) showed a more viscous interfacial film. HRG50- and HRG70-stabilized emulsions had better storage stability compared with other samples. Furthermore, the curcumin was loaded into Pickering emulsions using the pH-shift method. The light stability and gastrointestinal fate were assessed. Compared with curcumin-loaded HRG75-Pickering emulsion, HRG50-Pickering emulsion exhibited higher photochemical stability, whereas the lower FFAs release, bioaccessibility and transformation. This behavior was attributed to the thicker interfacial layer for HRG50 Pickering emulsion. This knowledge indicated that emulsion stabilized by HRG nanoparticles could be used as a delivery system to protect hydrophobic bioactive compounds. This research provided theoretical support to develop the utilization of HRG nanoparticles.