Unveiling the effect of natural deep eutectic solvents-based date seed polyphenolic extract on the properties of chitosan-PVA films and its application in shrimp packaging

This study explored natural deep eutectic solvent-based polyphenolic extract from date fruit seed as a functional and bioactive compound in chitosan-poly(vinyl)alcohol (CSPVA) films. Various concentrations of the extract (1.5 %, 2 %, 2.5 %, and 3 %) were added to study the effect on the film's bioactive, physicochemical, mechanical and structural properties. The extract increased the total phenolic content (0.01 to 0.16 mg GAE/mL), and antioxidant activities determined via 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity assay (1.45 to 5.53 mmol GAE/mL), and ferric ion reducing antioxidant power assay (0.12 to 2.4 mu mol TE/mL) assays. It also enhanced antibacterial activities against Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, and Escherichia coli. The extract was also successful in increasing the elongation at break (45.51 % to 58.16 %) and thickness (0.10 to 0.19 mm) while reducing tensile strength (11.18 MPa to 3.02 MPa) and Young's modulus (24.5 MPa to 5.7 MPa). UV-shielding ability, opacity, water vapor permeability (3.7 to 7.6 x 10-10 g/m.s.Pa) and solubility (53.7 % to 73.9 %) also increased. CSPVA films with 3 % DSP preserved white shrimps better than cling film by reducing quality deterioration (i.e., color, lipid oxidation, and bacterial population) after 4 days of refrigeration. These findings suggest that CSPVA films enriched with green-extracted date seed polyphenolic compounds hold significant potential for sustainable food packaging.