Characterization of Flaxseed Mucilage–Based Composite Biofilms Incorporating an Elastin/Collagen Matrix and Croton macrostachyus Leaf Extract for Active Food Packaging

Abstract

The growing demand for environmentally friendly alternatives to conventional plastic packaging has stimulated interest in biodegradable films with enhanced functional properties. In this study, active biofilms based on flaxseed mucilage (FSM) and elastin/collagen (ELN/COL), incorporated with Croton macrostachyus leaf extract (CMLE), were developed using the solvent evaporation method. Then, the physico-mechanical, optical, thermal, and antimicrobial properties of the resulting biofilms were systematically evaluated. FTIR analysis revealed the appearance of new peaks and peak shifts, indicating interactions between CMLE and the biofilm matrix. Incorporation of CMLE significantly reduced light transmittance while enhancing UV-barrier properties due to the presence of natural pigments. Water content and solubility decreased from 24.35 to 18.55% and from 84.21 to 72.59%, respectively, upon CMLE addition. Tensile strength increased from 4.90 to 7.28 MPa with 5% CMLE, whereas elongation at break decreased by 47.17% compared with the control biofilm. Differential scanning calorimetry showed an increase in melting temperature, suggesting improved compatibility among biofilm components. Thermal stability and antimicrobial activity were enhanced proportionally with increasing CMLE content. The CMLE-containing biofilms met the minimum requirements for tensile strength (0.39 MPa) and elongation at break (70%) for edible films. Notably, the elongation at break values were comparable to those of commercial Low-Density Polyethylene films (LDPE) films (68.70%). Overall, the results demonstrate that Croton macrostachyus leaf extract effectively improves the mechanical, functional, and bioactive properties of FSM-ELN/COL biofilms, highlighting their potential for sustainable packaging applications.