Green Valorization of Alfalfa into Sustainable Lignocellulosic Films for Packaging Applications

Plastic-based materials dominate the packaging industry. However, their non-biodegradability has increased the need for sustainable alternatives. Biopolymers, mainly lignocellulose from agricultural residues, offer renewable, eco-friendly options in this context. This study reports the development of lignocellulosic films from alfalfa (Medicago sativa) through green valorization of its biomass. Alfalfa lignocellulosic extract (ALE) was extracted using 50% NaOH, solubilized in 68% ZnCl2, crosslinked with CaCl2, and plasticized with sorbitol. The concentrations of ALE, CaCl2, and sorbitol were optimized using the Box–Behnken Design, focusing on increasing tensile strength (TS), elongation at break (EB), and reducing water vapor permeability (WVP) of the films. The optimized film formulation (0.5 g ALE, 453.8 mM CaCl2, 1.5% sorbitol) showed a TS of 11.2 ± 0.7 MPa, EB of 5.8 ± 0.9%, and WVP of 1.2 ± 0.2 × 10−10 g m−1 s−1 Pa−1. The film effectively blocked UV–Vis–IR light and exhibited notable antioxidant activity, making it suitable for packaging light-sensitive and oxidation-sensitive foods. Additionally, it achieved over 90% biodegradation within 29 days under 24% soil moisture. These findings demonstrate a sustainable approach to upcycling agricultural residues into functional products, offering a practical alternative to traditional plastics and supporting a circular bioeconomy, while adding value for alfalfa producers.