Adsorption of procyanidins onto chitosan-modified porous rice starch

Polyphenolic bioflavonoids are easily oxidized when exposed to oxygen during the processing or storage. This research developed a porous chitosan-modified starch for the adsorption of procyanidins. The modified starch was fabricated by a facile surface modification of chitosan on porous rice starch. Besides the investigation of the morphologies and structures of starches, the adsorption kinetics of procyanidins onto starches was evaluated. The modified starch was mesoporous with a relative moderate specific surface area at 1.13 ± 0.05 m2/g, and the interactions between starch and chitosan were intermolecular hydrogen bonds. The modification of chitosan resulted in the positive zeta potential of starch at pH 2-10. The enzymolysis reduced starch size slightly and induced a decrease in the apparent viscosity of starch suspension, while the modification of chitosan increased starch size and induced an increase in the apparent viscosity of the suspension. The adsorption capacity of the modified starch towards procyanidins was significantly improved and reached 96 ± 3% of the total amount of procyanidins, and the adsorption was chemisorption or strong surface complexation rather than mass transport. The results suggested that the porous chitosan-modified starch might be used as an efficient adsorbent for polyphenols.