Water vapor permeability, mechanical, and structural properties of edible beta-casein films

Edible films were made using glycerol and beta-casein that had been stored for 16 months at -29 and +22.5 degrees C. Water vapor permeability at 22.5 degrees C was determined for two relative humidity gradients. Stress-strain curves for mechanical property evaluation were obtained by dynamic mechani cal analysis. Film structure was observed by scanning electron microscopy a nd Fourier transform infrared spectroscopy. Protein storage temperature did not significantly affect water vapor permeability, elongation, or observed structure; however, differences in yield strength, modulus of elasticity, and tensile strength were detected, (C) 2000 Elsevier Science Ltd. All righ ts reserved.