In this study, transglutaminase was used to produce cross-linked casein, gelatin and casein-gelatin blend (100:0, 75:25, 50:50, 25:75 and 0: 100) edible films. Cross-linking was investigated by SIDS-PAGE. Mechanical and water vapor barrier properties of the films were characterized using ASTM procedures, and the film morphology was evaluated using scanning electron microscopy. The casein-gelatin film showed significant greater elongation values (P < 0.05) with or without transglutaminase treatment, as compared to films made from gelatin or casein alone. Mixtures of casein and gelatin produced a synergistic effect only observed in the film elongation, while no improvement was detected for tensile strength and water vapor barrier properties, except for the casein:gelatin (75:25) formulation with transglutaminase, which showed the lowest water vapor permeability value (5.06 +/- 0.31 g mm/m(2) d kPa). Enzymatic cross-linking also induced a substantial increase in the high molecular weight protein components in the film forming solutions. (C) 2005 Elsevier Ltd. All rights reserved.394458466