A Novel Source of Lignin from Date Palm Leaves as a Reinforcing Agent for Fabrication of Carboxymethyl Cellulose-Based Active Food Packaging Film

The present study was designed to extract the lignin fraction from date palm tree leaves and explore its incorporation into carboxymethyl cellulose (CMC) based composite films at varying concentrations as reinforcing agent. Structural studies revealed that the interaction between lignin and CMC improved the film characteristics and showed good compatibility between these polymers. X-ray diffraction (XRD) results revealed that the crystalline structure of CMC and lignin (CMC-Lignin) films was enhanced by the addition of lignin. The addition of lignin significantly enhanced the mechanical properties in terms of the tensile strength (TS) and elongation at break (EAB) of the CMC-Lignin films from 18.29 to 32.61 MPa and 32.5–45.3%, respectively. Physical properties in terms of thickness, solubility, moisture content, and water vapor permeability (WVP) were improved from 0.09 to 0.14 mm, 84.75 to 51.03%, 31.34 to 19.30%, and 4.98 to 1.08 × 10⁻¹⁰ g m⁻¹s⁻¹Pa⁻¹, respectively. The addition of lignin changed the optical properties of the films, making them darker and opaquer. CMC-Lignin films showed improved antioxidant and antimicrobial properties and manifest as viable alternatives to plastic packaging and can be successfully used as a sustainable packaging material in the food industry.