Carboxymethyl cellulose – Polyvinyl alcohol bioactive films loaded with green extracted date seed polyphenols for active packaging of Shiitake mushrooms

This study investigated the use of a natural deep eutectic solvent-based polyphenolic extract (DSE) from date fruit seed as a bioactive and functional component for the development of carboxyl methylcellulose-poly(vinyl)alcohol (CMCPVA) packaging films. The impacts on the physicochemical, structural, water barrier and bioactive properties of the CMCPVA films were studied. Different concentrations of DSE (1.5%, 2%, 2.5%, and 3%) incorporated into CMCPVA film increased the total phenolic content (0.08–0.17 mg GAE/mL), DPPH scavenging activity (4.08–5.11 mmol GAE/mL), and ferric ion-reducing antioxidant power (0.82–1.46 μmol TE/mL) of the films. The antibacterial activities against S. aureus, L. monocytogenes, S. typhimurium, and E. coli were also improved. In particular, a 4–5 log reduction was recorded for CMCPVA film incorporated with 3% DSE. Also, the presence of DSE enhanced elongation at break (25.53%–93.23%) and film thickness (0.10–0.19 mm), whereas tensile strength (6.39–1.40 MPa) and Young's modulus (25.89–2.85 MPa) decreased. Furthermore, UV-shielding performance improved, opacity decreased from 2.93 to 0.86, while the water vapor permeability was not significantly affected which ranged from 3.01 to 5.83 (X 10⁻¹⁰ g/m.s.Pa). The application of CMCPVA film incorporated with 3% DSE (CMCPVA_3) as a bioactive film for preserving sliced and whole shiitake mushrooms at refrigeration temperature for 8–12 days was studied. The CMCPVA_3 film preserved the mushrooms' color, browning degree, and texture compared to the cling film-covered samples. There is a potential for the successful application of NADES-based polyphenolic extract in biopolymer films for food preservation.