Immobilization of bioactive compounds in Cassia grandis galactomannan-based films: influence on physicochemical properties

Abstract

Galactomannan extracted from Cassia grandis seeds was used for the production of films containing different concentrations of the bioactive compounds lactoferrin (LF), bioactive peptides (BAPs), and phytosterols. SEM, FTIR, mechanical and thermal properties, colour, moisture content (MC), solubility, water vapour permeability (WVP), and contact angle (CA) were performed evaluating the effect of increasing concentrations of bioactive compounds on the films physicochemical properties. The immobilization of bioactive compounds leads to films with roughness on their surface, as observed by SEM. The thermal events demonstrated that bioactive compounds avoided the establishment of more hydrogen bonds when compared to galactomannan control film; this behaviour was also confirmed by FTIR. All the studied films had a strong whiteness tendency as well as a yellowish appearance. The addition of Lf reduced MC and solubility values and leads to an increase of WVP and CA values, while the addition of BAPs and phytosterols did not changed the film solubility. The mechanical properties were affected by the addition of bioactive compounds, which improved the stiffness of the films. Galactomannan-based films from C. grandis showed to be a promising structure for the immobilization of biomolecules, pointing at a significant number of possible applications in food and pharmaceutical industries.