• Films were developed with chitosan reinforced with almond shell nanocellulose. • Nanocellulose addition improved tensile strength (↑41%) and oxygen barrier (↓10%). • 2% NC-chitosan showed the best balance of strength, barrier capacity and opacity. • Shelf-life of almond oil, honey, and apple matched commercial sealing performance. Films based on nanocellulose (NC) derived from almond shell and chitosan were developed and evaluated as sustainable food-packaging materials. Films were prepared by solvent casting from a 1 % (w/v) chitosan solution containing 0 (control) 2, 4, or 6 % (w/w) NC (dry basis). The incorporation of 2 % NC markedly improved performance, increasing tensile strength from 42.6 to 97.9 MPa (41 % improvement) and reducing oxygen permeability from 3.1 to 2.8 cm 3 ·µm/(m 2 ·day·kPa) (10 % reduction). Importantly, water vapour permeability remained unchanged at 2 % NC (8.7 × 10 -11 g·m/(Pa·s·m 2 )), but increased at higher loadings, indicating that 2 % NC maximized mechanical enhancement without compromising barrier performance. The 2 % NC formulation was selected for shelf-life studies in almond oil, honey and fresh-cut apple, and compared with polypropylene caps, low-density polyethylene (LDPE) film and hermetic closures. In almond oil, the chitosan-NC film significantly delayed the increase of oxidation markers (K 232 , K 270 ) demonstrating oxygen-limiting protection under non-hermetic conditions. In honey, although moisture content slightly increased under chitosan-NC sealing, total phenolic content and diastase activity remained stable, indicating preservation its quality parameters. In fresh-cut apple, chitosan-NC promoted greater moisture loss and increase in °Brix concentration without browning or acidification, indicating no oxidative or enzymatic deterioration. Effect size analysis revealed matrix-dependent preservation mechanisms: storage time dominated deterioration in oil and honey (> 90 %), whereas packaging type governed moisture loss in apple (96 %). Overall, the 2 % chitosan-NC film matched conventional packaging while providing biodegradability and strong potential for lipid-rich food applications.
Están et al. (Fri,) studied this question.