Alkali-digested alfalfa lignocellulose for sustainable UV-blocking packaging films

Area of Science:

• Materials Science
• Sustainable Chemistry
• Biotechnology

Background:

• Growing environmental concerns regarding plastic persistence necessitate sustainable packaging alternatives.
• Biopolymers are studied, but a need exists for abundant, renewable biomaterials from non-food sources.
• Lignocellulose from agricultural residues offers a promising, sustainable feedstock for biomaterial development.

Purpose of the Study:

• To develop biodegradable packaging films from lignocellulose sourced from alfalfa agricultural residues.
• To optimize the formulation and processing of these films for desirable mechanical and barrier properties.
• To evaluate the films' suitability for packaging sensitive food products and their environmental impact.

Main Methods:

• Extraction of lignocellulose from alfalfa residues using 20% NaOH.
• Solubilization, crosslinking, and plasticization of lignocellulose using ZnCl2, CaCl2, and sorbitol at 83°C.
• Film casting, regeneration with ethanol, washing, drying, and characterization using Box-Behnken Design for optimization.

Main Results:

• Optimal formulation achieved tensile strength of 5.7 MPa, elongation at break of 8.3%, and water vapor permeability of 1.4 × 10⁻¹⁰ g·m⁻¹·s⁻¹·Pa⁻¹.
• Films demonstrated strong UV-Vis-IR light-blocking capacity and antioxidant activity.
• Complete biodegradation within 35 days in soil, following Peleg's water-absorption kinetics.

Conclusions:

• Alfalfa agricultural residues can be effectively converted into high-performance biodegradable packaging films.
• These films offer a sustainable alternative to conventional plastics, reducing pollution and supporting a circular bioeconomy.
• The process provides socioeconomic benefits by valorizing agricultural waste and creating new revenue streams for farmers.