Valorization of Wheat Straw Cellulose into Biodegradable Packaging Films for Fresh Produce Preservation

The growing environmental impact of petroleum-based plastic packaging has accelerated the development of biodegradable materials from renewable resources. In this study, cellulose extracted from wheat straw was regenerated into biodegradable films using calcium-ion crosslinking and glycerol plasticization. A Box-Behnken experimental design optimized cellulose content (0.35-0.5 g), calcium chloride concentration (200-800 nm), and glycerol concentration (0.5-1.5%) to produce films with balanced mechanical and barrier properties. The optimized film was characterized for its physicochemical, mechanical, optical, antioxidant, and biodegradation properties and evaluated for fresh grape packaging. The film exhibited favorable mechanical strength of 30.82 ± 4.70 MPa, controlled water vapor permeability of 0.59 ± 0.06 10^-10 gm^-1 s^-1 Pa^-1, elongation at break of 4.36 ± 0.35%, moderate transparency of 22.95 ± 0.65% mm^-1 at 600 nm, and ultraviolet light-blocking capability, allowing only 9.57 ± 1.44% of UV-B at 300 nm, and an IC₅₀ value of 0.33, indicating moderate antioxidant potential, with 35% biodegradation after 37 days at a soil moisture of 24%. During ambient storage, grapes packaged with the film reached 15% weight loss by 13 days, while slowing changes in total soluble solids, pH, titratable acidity, total phenolic content, and vitamin C, and delaying visible quality deterioration. Compared with the uncovered control, packaged grapes maintained acceptable quality for approximately six additional days, reaching 15 days of storage. Unlike conventional polystyrene film, which promoted excessive gas accumulation and fruit cracking, the wheat straw cellulose film provided a semipermeable barrier that balanced moisture and gas exchange. The systematic optimization of these formulations, followed by comprehensive characterization of the optimized films, demonstrates the potential of wheat straw cellulose as a functional material for developing cellulose films as sustainable, biodegradable packaging materials for extending the postharvest quality of fresh produce.