Efeito da adição de cera de abelha sobre as propriedades de filmes biodegradáveis elaborados com gelatina da pele de peixe

Abstract

Biodegradable films are defined as thin materials made from biomolecules, which act as a barrier against moisture, gases, light and mechanical injuries and, consequently, extend the shelf life of products. Biodegradable films made from biomolecules have gained visibility today, especially those made from gelatin extracted from fish skin. Despite having good optical and mechanical properties, they have high water vapor permeability (PVA). The addition of lipids such as beeswax is a good option to solve this problem. The objective of this work was the elaboration and characterization of a biodegradable film from yellow hake skin gelatin added with beeswax using sodium dodecyl sulfate (SDS) and stearic acid as a surfactant, aiming to improve the technological properties of the film. A complete factorial design was carried out to define the region with the best barrier and solubility of the films. The planning indicated the tendency of the concentrations for the best results of the characteristics of the film. Based on this, four films of film-forming solution containing 130 ml were prepared, the first being a Control film composed of 2% gelatin and 20% glycerol; second film (F1) composed of 2% gelatin, 20% glycerol, 5% beeswax, 80% SDS and 100% stearic acid; third film (F2) composed of 2% gelatin, 20% glycerol, 10% beeswax, 80% SDS and 100% stearic acid and the fourth film (F3) composed of 2% gelatin, 20% glycerol, 15% beeswax, 80% SDS and 100% stearic acid. The thickness of the films presented heterogeneous results due to the poor incorporation of the wax in the film matrix. Likewise, the addition of beeswax to the film did not have a positive influence on PVA because of the appearance of bubbles in the film-forming solution. However, all films obtained excellent solubility results, justified by the high hydrophobicity of the wax. The films obtained results that indicate opaque films with greenish yellow tones and high luminosity, with an excellent UV barrier, and can be used in foods with sensitivity to light. The microstructure analysis showed inhomogeneous films, with bi-layer-like structures, free spaces and cracks in the matrix.