Comparative characterization of the zein/propylene glycol alginate nanoparticles prepared by complex coacervation in aqueous ethanol.

Novel zein/propylene glycol alginate nanoparticles (ZP-NPs) prepared by complex coacervation in 70 % aqueous ethanol were characterized and compared with those fabricated by the conventional antisolvation (ZP-NPa) and pH cycling (ZP-NPc) methods. Zeta potential and particle size measurements as well as scanning electron microscope and intrinsic fluorescence analysis confirmed that ZP-NPs possessed a different component distribution and microstructure. ZP-NPs were more hydrophobic according to surface hydrophobicity measurement and a contact angle closer to 90° (88.5°), more dispersible in water, and more effective in reducing the interfacial tension and absorbing to Pickering emulsion interfaces. ZP-NPs can produce stable and homogeneous Pickering emulsions with tuna oil fractions ranging from 20 % to 50 %, and the emulsions exhibited greatly enhanced stability against storage, heating, and repeated freezing-thawing, that is, no obvious appearance change and only mild coalescence was observed after storage at room temperature for 21 d, three freezing-thawing cycles, or heating at 80 °C for 2 h. Besides, ZP-NPs were more efficient in delaying the oxidation of tuna oil trapped in Pickering emulsions. Hence, ZP-NPs are potential alternative to the conventional zein nanoparticles and can find wide applications in the food industry.