Improvement of stability and in vitro bioaccessibility of nervonic acid by nonionic surfactant in protein-based nanoemulsions

Nervonic acid (NA, ω-9) is beneficial for brain health, but its poor water solubility limits its bioaccessibility. The protein-based emulsions were unstable under environmental stress. In this study, the effects of a nonionic surfactant (Tween 20, T20) on the characteristics, stability, and in vitro digestion properties of NA-loaded nanoemulsions prepared with proteins (whey or soybean protein isolate) were evaluated. The emulsions stabilized by protein-T20 mixtures had smaller droplets with more even distributions, more negative charges, and higher encapsulation efficiencies for NA. The addition of T20 improved the interfacial properties of the systems, as confirmed by spectral and rheological analyses. Emulsion stability under various conditions was enhanced by the improved interfacial composition and emulsifying ability. In particular, the effective interfacial layers produced by the protein-T20 mixture decreased lipid digestion but increased NA bioaccessibility. Therefore, the co-adsorption of proteins with suitable nonionic surfactants at oil-water interfaces is a promising approach for designing functional food delivery systems with improved stability and NA bioaccessibility.