Regenerated lignocellulosic material from pea, bean, and artichoke waste as feedstock for bioplastic production

Vegetable processing generates large quantities of lignocellulosic waste that are often underutilized. Developing bioactive, biodegradable packaging materials from such residues aligns with circular bioeconomy goals. This study explores oxalic acid-choline chloride deep eutectic solvent (DES) fractionation as a green approach to valorize artichoke bracts, pea pods, and bean pods into high-performance lignocellulosic bioplastics.

The aim was to regenerate lignocellulosic matrices in situ and fabricate bioplastics with tailored structure-property relationships, while providing mechanistic insights into the molecular interactions governing their performance.

Raw wastes were subjected to DES fractionation, which selectively reorganized cellulose, depolymerized hemicellulose, and regenerated lignin. Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to confirm structural changes. Mechanical, barrier, thermal, antioxidant, antimicrobial, and biodegradation properties were evaluated. Molecular docking simulations were performed to investigate lignin-cellulose interactions.

DES treatment produced dense fibrillar networks in artichoke-derived bioplastics and more porous architectures in pea and bean pod bioplastics. Molecular docking indicated favorable lignin-cellulose interactions (binding energies - 4.9 to - 5.2 kcal/mol) stabilized by oxalic acid-mediated hydrogen bonds, supporting enhanced matrix cohesion. Artichoke bract bioplastics exhibited the highest tensile strength (7.02±0.68 MPa) and Young's modulus (428.11±44.47 MPa), whereas bean pod bioplastics achieved the highest elongation at break (8.35±1.30 %). Pea pod bioplastics offered superior water vapor barrier properties. Thermal stability was enhanced (T_d = 244-266 °C), UV-Vis light transmittance was below 2 %, and the films retained antioxidant and antimicrobial activity. Soil burial tests showed 56-69 % mass loss within 70 days, indicating rapid biodegradability.

This work demonstrates that DES-mediated regeneration of lignocellulosic material is an effective strategy to produce multifunctional, bioactive, and environmentally degradable bioplastics. By correlating molecular-level lignin-cellulose interactions with macroscopic mechanical, barrier, and bioactive properties, the study provides mechanistic insight and practical guidance for the rational design of sustainable packaging materials within a circular bioeconomy framework.