Fabrication and characterization of curcumin-loaded nanoparticles using protein from brewers' spent grain.

Using plant-derived proteins as delivery materials to encapsulate lipophilic bioactive compounds is of great interest. Three protein fractions from brewers' spent grain (BSG) were extracted by the alkaline or alcoholic method with different procedures, and their potential to encapsulate curcumin was evaluated by preparing composite nanoparticles stabilized by lecithin using a pH-cycle method. The three protein fractions showed considerably different encapsulation properties. The particle size and entrapment efficiency varied from 173 to 306 nm and 21.2% to 83.9%, respectively. Compared with the other two fractions, the one extracted with 55% (v/v) ethanol showed better encapsulation performance. Curcumin after encapsulation exhibited an enhanced UV light and thermal stability while its antioxidant activity maintained. These results suggested that BSG protein could be a promising delivery material to encapsulate the water-insoluble bioactive compounds. • Protein fractions were extracted from brewers' spent grain (BSG) by alkaline or alcoholic methods. • Composite nanoparticles were prepared using BSG protein fractions to encapsulate curcumin. • BSG protein fraction obtained by 55% (v/v) ethanol showed better encapsulation performance. • BSG protein improved the UV light and thermal stability of curcumin without receding antioxidant activity. [ABSTRACT FROM AUTHOR]