Complexation between burdock holocellulose nanocrystals and corn starch: gelatinization properties, microstructure, and digestibility in vitro

Holocellulose nanocrystals (hCNCs), with hydrodynamic diameters (D-Z) ranging from about 600 to 200 nm, were prepared by treating burdock insoluble dietary fiber (IDF) with enzymes and ultrasonic power. It was revealed that hCNCs improved the viscosity of corn starch (CS) during pasting and inhibited its short-term retrogradation. Besides, the crystallinity, short-range order of the double helix, viscoelastic properties, and microstructure compactness of CS gels improved remarkably in the presence of burdock hCNCs. These effects were both size- and dose-dependent, which primarily originated from the hydrogen bonding between hCNCs and amylopectin or leached amylose. In this regard, the digestion of CS gels containing hCNCs was remarkably retarded because of the reduced accessibility of digestive enzymes to the glycosidic bonds. Therefore, burdock hCNCs, prepared from natural resources using green techniques, hold potential applications in functional foods of a low glycemic index.