Cross-linked zein articles are prepared by a melt process where zein is mixed with polyethylene maleic anhdyride. The melt processing can be conducted as a batch process (e.g., as in a torque rheometer) or as a continuous process (e.g., as in reactive extrusion using a screw extruder). This process provides a zein article that has reduced solubility in acetic acid (a solvent that normally dissolves unaltered zein) and/or increased tensile strength.