Constrained mixture design applied to the development of cassava starch-chitosan blown films

► Starch-chitosan-glycerol blends were studied in extruded films. ► Small amounts of chitosan (<5%) increase the mechanical resistance of starch films. ► Intermolecular hydrogen bonds between chitosan and starch reinforce the films. ► Water vapor permeability of films is decreased by these low chitosan concentration. ► The constrained mixtures design was useful for this study.