Biocomposites Based on PHBV and the Lignocellulosic Residue from Horchata Production

The use of agro-industrial residues in the development of packaging materials is a topic of interest from a sustainable perspective, as it promotes biodegradability, reduces production costs, and aligns with the concept of a circular economy. The aim of this work was to develop and characterize biodegradable composite films based on Poly 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) and the tiger nut horchata solid residue (HSR) at different ratios. The obtained composites were evaluated as to their suitability as food active packaging materials in terms of microstructure, water content and solubility, mechanical, barrier and thermal properties, and total phenolic content and antioxidant capacity. The incorporation of HSR into the PHBV matrix led to more opaque, darker reddish films and promoted significant changes in their mechanical and barrier properties. Specifically, the composite films showed lower water vapor barrier capacity and reduced tensile strength (43-81% lower TS) and elongation at break (46-77% lower Ɛ values) while the rigidity increased or maintained when using up to 20% wt. of HSR. In contrast, the incorporation of the HSR provided the films with remarkable antioxidant capacity and effective light-blocking capacity, which could be of great interest for food preservation, as active packaging materials. The total phenol content of the composites increased in line with the increment of the HSR content, ranging from 9 to 34 mg GAE/100 g film.