Self-assembled zein hydrolysate glycosylation with dextran for encapsulation and delivery of curcumin

Curcumin has been widely used to promote human health and nutrition due to its high antioxidant capacity. However, its low solubility and bioaccessbility limit its practical application. In this study, we used glycosylated zein hydrolysate to encapsulate hydrophobic curcumin to improve its bioaccessbility and stability at extreme processing conditions. Glycosylated zein hydrolysate exhibited good amphiphilicity and self-assembly properties. The nanoparticles, made up of glycosylated zein hydrolysate encapsulated curcumin, had a number-average particle size of 117 nm, polydispersity coefficient (PDI) value of 0.16 and high apparent loading efficiency value of 81%. Under the observation of TEM and AFM, the nanoparticles were spherical, stable and uniform in particle size distribution, and dispersed well in the solution after dilution. Steady-state fluorescence spectroscopy showed that there is a strong affinity between curcumin and glycosylated zein hydrolysate with Ka value of 3.17 × 105 M−1. The bioaccessbility of nanoparticles was 86%, increasing the bioaccessbility of curcumin by 9 times. The covalently bound dextran formd the protective layer on the outside of the nanoparticles, which could effectively resist the destruction of gastric enzymes, significantly increase the retention rate in the gastric digestion stage and achieve release in the intestinal tract. In addition, the stability of nanoparticles in various environment with different ionic strengths NaCl (∼600 mM)/Ca2+ (∼50 mM) and temperature (∼90 °C) were significantly enhanced.