Edible Films Based on Casein with Karaya Gum or Pectin: Formulation Influence on Physicochemical and Antioxidant Features

Edible films are food preservation technologies that can have the strongest physicochemical and antioxidant characteristics, depending on their formulation. For this, the objective of this research was to evaluate the influence of the formulation on the physicochemical and antioxidant properties of edible films based on casein (C, with 1, 2 or 3%) and karaya gum (G, with 2 or 3%), pectin (P, with 2 or 3%), or the combination karaya gum–pectin (GP, 2 or 3%). A total of 21 formulations were prepared, and the physicochemical (pH of the film-forming solution, thickness, tensile strength, elongation at break, moisture content, water solubility, swelling ratio, water vapor transmission rate, color difference) and antioxidant characteristics (total phenolic compounds and antioxidant capacity) were evaluated. The pH of the film-forming solution and the thickness increased upon the addition of G, P and GP. The most suitable formulation in terms of mechanical properties was 3C-2P, with 4.96 MPa of tensile strength, 47.53% elongation at break and 28.01 g/m2 day of WPTR; however, it has high moisture content (38.02%) and water solubility (81.51%). In terms of the antioxidant features, 3C-2P films had an average concentration of TPC (106.41 mg of gallic acid/100 g of edible films) and antioxidant capacity (8.28% of DPPH inhibition). Developing edible films with appropriate physicochemical and antioxidant properties is crucial for the proper preservation of fresh and perishable products, as the ingredients used in their formulation can interact and produce synergistic or antagonistic effects.