Effect of Fatty Acids and Beeswax Addition on Properties of Sodium Caseinate Dispersions and Films

Edible films based on sodium caseinate and different saturated fatty acids, oleic acid, or beeswax were formulated. Film-forming emulsions were characterized in terms of particle size distribution, rheological behavior and surface tension. In order to evaluate the influence of lipids on sodium caseinate matrices, mechanical, optical, and water vapor barrier properties were studied, taking into account the effect of water content and film structure on such properties. Saturated fatty acids affected the film properties in a particular way due to the formation of bilayer structures which limited water vapor permeability, giving rise to nonflexible and more opaque films. Oleic acid and beeswax were less effective as water vapor barriers, although the former imparted more flexibility to the caseinate films and did not reduce the film transparency notably.