Chitosan-caffeic acid-genipin films presenting enhanced antioxidant activity and stability in acidic media

► Methodology optimization to link caffeic acid by a radical mechanism to chitosan. ► Films preparation of chitosan grafted with caffeic acid and cross-linked with genipin. ► Developed films had higher antioxidant activity and low solubility in acid pH than the pristine films. ► These films can be promising to be used as active materials in acidic media.