Matrix-Dependent Performance of β‑Glucan Composite Films Functionalized with Phenolics from Passion Fruit Seed Waste

The valorization of agro-industrial waste for producing sustainable and functional packaging is a key strategy within the circular economy and green chemistry. This study developed active antioxidant edible films by incorporating a phenolic-rich extract from yellow passion fruit seeds into two composite polysaccharide matrices: β-glucan/carboxymethyl cellulose (BG/CMC) and β-glucan/citrus pectin (BG/PEC). The phenolic extract, obtained through a sequential ultrasound-assisted extraction from defatted yellow passion fruit seeds, was incorporated into the film-forming solutions at different concentrations (0, 57, 114, and 190 μg GAE/mL), which were subsequently cast and dried. The films were thoroughly characterized. Both film series exhibited excellent UV light barrier properties and homogeneous morphology. The BG/CMC films were fully water-soluble and showed the highest antioxidant activity (up to 19.42 μmol TE/g by TEAC assay) at the highest extract concentration. In contrast, BG/PEC films demonstrated superior and enhanced mechanical properties when loaded with the highest extract amount, achieving a balanced combination of tensile strength (3.64 MPa) and elongation at break (20.84%). Structural analyses (FTIR, XRD, and TGA) confirmed the successful incorporation of the extract and revealed an amorphous structure with good thermal stability. The BG/PEC films showed visible enhancement on thermal stability with the incorporation of the phenolic extract, in any concentration, with a final mass loss near 30%. All films showed good synergy within the matrices ingredients, corroborated by the FTIR spectra where the main bands were still present. The results demonstrate that the choice of the polysaccharide matrix (CMC vs pectin) dictates the final functional profile of the active film. This work successfully transforms passion fruit processing waste into tailorable, antioxidant edible films, providing sustainable alternatives for active food packaging applications.