Physical, morphological, and barrier properties of edible casein films with wax applications

The overall research objective was to investigate the effects of wax application to casein films on the physical, morphological, mechanical, and water barrier properties of the films. Casein films were prepared by cross-linking with zein hydrolysate using transglutaminase. Wax was either incorporated into the film-forming solution or coated onto the casein films. The physical, morphological, and mechanical properties of wax-incorporated or wax-coated casein films were characterized. The wax-casein films exhibited darker color than casein film, and the film thickness ranged from 0.2 to 0.4 mm. Wax application significantly decreased the tensile strengths and Young's Modulus of casein films. The wax-incorporated films exhibited a greater reduction in tensile strength and Young's Modulus than the wax-coated films. The microstructures of wax-casein films were relatively smooth and uniform when observed under a scanning electron microscope. Wax applications significantly decreased the water vapor permeability (WVP) of the casein films, and the wax-coated casein films exhibited a greater decrease in WVP than the wax-incorporated films.