Development of edible films prepared by soy protein and the galactomannan fraction extracted from Gleditsia triacanthos (Fabaceae) seed

Abstract

The study of by-products of the food industry or of unexploited plant components represents a research field in full expansion, which focuses on increasing their value by discovering new functionalities and applications. In the present study, we explored the film-forming properties of the galactomannan fraction extracted from Gleditsia triacanthos (Fabaceae) and its ability to improve the properties of soy protein films when used as a co-component. It was found that improved films could be obtained through the combination of both components in certain ratios in relation to single component samples. The opacity, luminosity, and thickness of the films were higher in those films prepared with both components. Due to their interactions, using some proportions of these components produced an important decrease in the effects of water on the films. Moisture content, total soluble matter and swelling in water were markedly decreased by the addition of galactomannan, in agreement with contact angle studies which showed a reduction in the hydrophilicity of the surfaces. From tensile tests, it was observed that the polysaccharide component had a greater tensile strength and less elongation capacity than those of the protein. The combination of both components produced better films, as the described synergic effect between components allowed the development of films with improved characteristics, with a great potential to be used as food packaging.