Valorization of Red Pitahaya (Hylocereus sp.) Peel Through a Multi-Product Cascade Biorefinery Approach Towards Bioactive Food Packaging Films

This study proposes efficient valorization of red pitahaya (Hylocereus sp.) peels by separating and purifying their structural and bioactive fractions to produce bioactive films through a multi-product cascade biorefinery approach. The process begins with the extraction of a betalain-rich extract (BET), followed by the separation of pectin (PEC), and finally, the production of cellulose nanofibers (CNF) from the remaining residue. The entire cascade process resulted in a successful utilization of 79.5% of the pitahaya peel. All fractions obtained were integrated into PEC-based films reinforced with CNF in the following proportions 5, 15, 30 and 45% CNF. The films were subsequently subjected to characterization in terms of their physical, chemical and mechanical properties. The optimal mechanical reinforcement effect was observed in films with 45% CNF, which exhibited an increased tensile strength of 20.47 MPa compared to 100% PEC, and higher thermal stability. Therefore, the ratio of 45% CNF was selected for the addition of the bioactive fraction, which comprised 5, 10, 15, 20, 30, 40 and 50% BET. In general, all bioactive films exhibited a compact and uniform structure. Films with higher percentages of BET showed a decrease in water vapor barrier properties (50-70% increase in water vapor permeability), probably due to the hydrophilic nature of BET. Additionally, the inclusion of BET resulted in enhanced wettability, as evidenced by a reduction in water contact angles (36.36º). The UV light blocking capacity increased (57% increase) while transparency decreased (43-50%) with the addition of BET.