Formulation and Characterization of Chitosan Films Incorporating Hawthorn Polyphenolic Extracts via Natural Deep Eutectic Solvents

What if the key to smarter food packaging lies in a humble berry and a green solvent? A new study turns hawthorn polyphenols into flexible, antioxidant-rich films.

Plastic waste is choking the planet, but scientists are fighting back with biodegradable films made from chitosan—a natural polymer from shellfish shells. The twist? They're using natural deep eutectic solvents (NaDES), a green chemistry marvel, to both plasticize the films and extract bioactive compounds from hawthorn (Crataegus monogyna). This dual role makes the process efficient and eco-friendly.

In the lab, researchers mixed chitosan with NaDES (choline chloride and glycolic acid at a 1:3 molar ratio) at concentrations from 44 to 70 wt%. The 50 wt% formulation hit the sweet spot, balancing mechanical strength and barrier properties. When they added hawthorn extract, the films became dramatically more flexible—Young's modulus dropped from 131 to 30 MPa, and tensile strength fell from 24 to 12 MPa. Stress-strain tests confirmed that more NaDES meant softer films, proving its plasticizing effect.

FTIR analysis showed strong hydrogen bonding between chitosan and NaDES, and confirmed the polyphenols were well-integrated. The films were smooth, dense, and homogeneous, with excellent UV-blocking ability—especially when loaded with extract, which extended protection into UVA and visible light. But the star feature? Antioxidant activity nearly doubled, as measured by DPPH radical scavenging, compared to plain chitosan films.

These films aren't just tough—they're smart. With combined mechanical flexibility, light barrier, and antioxidant power, they're a promising step toward sustainable active packaging that could keep food fresher for longer.

Key Points

• 50 wt% NaDES gives optimal mechanical and barrier performance.
• Hawthorn extract doubles antioxidant activity in chitosan films.
• Films show enhanced flexibility and UV-blocking properties.