Plasticizing Effects of Beeswax and Carnauba Wax on Tensile and Water Vapor Permeability Properties of Whey Protein Films

ABSTRACT: The possible plasticizing effect of beeswax (viscoelastic wax) and carnauba wax (elastic wax) on tensile and water vapor permeability properties of whey protein isolate (WPI) films was studied. For the experiments, 3 groups of films with different WPI:glycerol ratios (1:1; 1.5:1; 2:1, 2.5:1, and 3:1) were prepared. The 1st group was made without the addition of wax, and the latter 2 groups were made with the addition of beeswax and carnauba wax, respectively, mixing 1 part of wax to 1 part of WPI. Lipid particle size, water vapor permeability, tensile properties, and thickness of films were analyzed and measured. The results show that the incorporation of beeswax produced a plasticizing effect in WPI:glycerol films, whereas carnauba wax produced an anti-plasticizing effect. The moisture barrier properties of WPI:glycerol films benefit from the addition of beeswax, by both increase of the hydrophobic character and decrease of the amount of hydrophilic plasticizer required in the film.