To address the limitation of strong hydrophilicity of edible films, starch/gelatin (S/G) films incorporated with natural waxes (beeswax (BW), candelilla wax (CL), and carnauba wax (CB)) were fabricated by extrusion blowing. Rheological analysis demonstrated that the incorporation of natural waxes reduced storage modulus and complex viscosity of S/G blends. BW and CL weakened molecular interactions among film components, whereas CB did not. CB exhibited the strongest crystalline behavior after film formation. The degree of starch gelatinization and water vapor barrier property of films depended on wax type. The presence of waxes increased the water resistance and surface hydrophobicity of the films. However, CL and BW addition decreased the tensile strength of films. The highest water contact angle (102.6°), strongest thermal stability, and lowest water vapor permeability were found in S/G-BW film, which could be the optimal choice to produce highly hydrophobic edible films.
Keywords: Edible film; Extrusion blowing; Gelatin; Natural wax; Starch.
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