Green Extraction of Lignin From Date Palm ( Phoenix dactylifera L.) Seed Waste and Its Integration Into Alginate‐Based Films With Improved Moisture Resistance, Antioxidant Capacity, and Surface Hydrophobicity for Food Packaging Applications

Abstract

The aim of the current study was to extract lignin‐rich fraction from date palm ( Phoenix dactylifera L.) seeds and evaluate its application as a filler in sodium alginate‐based films for food packaging applications. Lignin was isolated through a sonication‐assisted mild alkaline hydrolytic process followed by acid precipitation. The isolated lignin was then characterized by using FTIR, XRD, SEM, and DSC analysis. FTIR analysis confirmed the presence of characteristic hydroxyl and aromatic functional groups associated with lignin. XRD analysis showed a low‐crystallinity with a broad diffraction region linked with amorphous lignin. SEM analysis showed an irregular and porous morphology. DSC demonstrated favorable thermal behavior. Sodium alginate and lignin films were developed by adding lignin into the sodium alginate matrix at various concentrations by using the solution casting method. The light transmittance and water vapor transmission rate decreased with the addition of lignin. The haze value and antioxidant activity of the films increased with the increase in lignin concentration and improved the light‐blocking ability. However, incorporating lignin did not significantly modify the mechanical properties of the films. The sample with the highest lignin concentration showed improved surface hydrophobic properties. These findings suggest that the date seed‐derived lignin could be a suitable candidate for food packaging applications.