Zero-waste valorization of whole mango byproducts into distinct functional packaging films via mild hydrothermal and alkaline pretreatments

The compositional heterogeneity of agro-industrial byproducts presents a significant challenge for engineering high-performance bio-based materials without resource-intensive macromolecular separation. Here, an eco-efficient strategy is proposed for the comprehensive valorization of whole mango byproducts (MBPs), including peels and finisher pulp (PeP), seed tegument (SeT), and kernel (SeK), into functional bioplastics intended for food packaging. To disrupt the organized biomass structure for subsequent assembly into films, MBPs were subjected to mild hydrothermal pretreatment (HTP) or dilute alkaline pretreatment (DALP), which selectively partitioned amorphous biomass components and induced distinct structural responses according to the mango byproduct. While HTP better preserved solubilized carbohydrates, DALP promoted more extensive pectin saponification and hemicellulose solubilization. Bioplastic films were then prepared using pretreated PeP, SeK, or a mixture of all byproducts (PePSe). The incorporation of only 10% carboxymethyl cellulose (CMC) improved film mechanical performance, yielding tensile strength values of up to 11 MPa. The SeK-based films exhibited the lowest water vapor permeability (2.3 g mm kPa −1 h −1 m −2 ), and all CMC-containing films displayed hydrophobic surfaces (water contact angle > 90°). All bioplastics provided near-total UVA and UVB shielding (>97%), while the PeP-based films exhibited the highest transparency (>43%). Although the antioxidant activity of the bioplastics decreased compared to that of the corresponding raw MBPs, the PeP-DALP-CMC film retained at least 50% of it. By demonstrating that biomass heterogeneity can be harnessed, rather than eliminated, to tailor functional bioplastics, this simple and effective approach emerges as a potentially scalable strategy for producing sustainable active packaging materials.