Nanoparticles prepared by proso millet protein as novel curcumin delivery system

Encapsulation of lipophilic bioactive compounds using plant-derived proteins as delivery systems has received increasing interest. In this study, proso millet protein was extracted by either wet milling or 60% (v/v) aqueous ethanol and then used as the wall material to encapsulate curcumin. Millet protein was composed of prolamines that showed a significant difference in surface hydrophobicity depending on extraction procedure. The millet protein-curcumin nanoparticles were spherical with diameter around 250–350 nm. The entrapment efficiency ranged from 11.2% to 78.9%, with millet protein extracted by ethanol showing better performance than that by wet milling process. The encapsulated curcumin exhibited a lower degradation rate than free curcumin at 60 °C. The encapsulation showed no negative effect on the antioxidant activity of curcumin as assessed by the DPPH and ABTS assays. These results suggested that MP could be a promising encapsulant for the delivery of lipophilic compounds.