Integrated valorization of durian rind into bioactive carboxymethyl cellulose hydrogels: Co-recovery of flavonoids and cellulose with physicochemical, functional, and economic evaluation

The durian industry generates substantial rind waste, causing serious environmental issues and resource loss. This study proposed an integrated valorization approach to transform durian rind into high-value biomaterials by co-recovering a flavonoid-enriched extract and cellulose for the fabrication of bioactive carboxymethyl cellulose (CMC) hydrogel films. Solvent extraction and fractionation yielded multiple bioactive fractions, with the chloroform fraction exhibiting the highest total flavonoid content (281.33 mg QE/g extract) and quercetin concentration (1.0 mg/g extract). Cellulose remaining in the post-extraction residues was optimally isolated with high yield (27.10%) and purity (93.39%) and subsequently modified into CMC. The resulting CMC was crosslinked with citric acid to fabricate hydrogel film loaded with the chloroform fraction. FTIR analysis confirmed esterification-based crosslinking, while SEM observations revealed morphological changes induced by crosslinking and flavonoid incorporation. Hydrogel film prepared with 10% citric acid exhibited optimal network formation and mechanical performance. In vitro release studies showed an initial rapid release followed by sustained diffusion, with 65.34% flavonoid release after 24 h for hydrogel films loaded with 1% chloroform fraction. The fabricated hydrogel film demonstrated potent in vitro antioxidant activity (IC 50 = 55.75 μg/mL, DPPH inhibition), anti-inflammatory activity (IC 50 = 610.70 μg/mL, BSA denaturation), and antibacterial activity against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli (inhibition zones: 10 – 14 mm). Economic assessment demonstrated the process as cost-effective and scalable potential. This integrated approach offers a sustainable route to produce multifunctional, bioactive hydrogels from durian rind, advancing waste valorization and contributing to circular bioeconomy and sustainable material developments.