β-Cyclodextrin-incorporated dialdehyde cellulose nanocrystal-reinforced CMC/PVA films for active packaging of strawberries.

Abstract

Strawberry deterioration is accelerated by moisture imbalance, microbial contamination, and rapid metabolic activity, emphasizing the need for active packaging materials beyond passive protection. Carboxymethyl cellulose/poly(vinyl alcohol) (CMC/PVA) films were engineered with dialdehyde cellulose nanocrystals (DCNC) and β-cyclodextrin (β-CD) as dual-component active packaging materials for strawberry preservation. DCNC was prepared via periodate oxidation and exhibited an aldehyde content of 8.39 ± 0.02%, supporting its role as a reactive nanoreinforcing component within the CMC/PVA matrix. The aldehyde groups of DCNC promoted interfacial interactions with hydroxyl-rich polymer chains, while β-CD introduced additional hydrogen-bonding sites and supramolecular cavities. The mechanical, barrier, antimicrobial, cytocompatibility, and strawberry-preservation performances of the films depended on β-CD content. Although the CMC/PVA/DCNC3%/β-CD0.20% film showed the highest tensile strength of 44.1 MPa and the highest antibacterial reduction against S. aureus of 99.99%, the CMC/PVA/DCNC3%/β-CD0.15% film provided the most balanced active-packaging performance. This selected formulation maintained high tensile strength of 38.6 MPa, exhibited the lowest WVTR of 74.88 g m-2 24 h-1, showed an OTR of 19 cc m-2 24 h-1, and achieved the highest antifungal reduction against A. niger of 99.01%. Overall, the films achieved 95.89-99.99% reduction against S. aureus (ATCC 6538P) and up to 99.01% reduction against A. niger (ATCC 10864), while showing high L929 cell viability of 103-108%. In strawberry storage tests, the selected CMC/PVA/DCNC3%/β-CD0.15% film retained firmness at 82.09%, limited the TSS increase to 13.51%, and better maintained titratable acidity after 5 days. These findings support the use of β-CD-incorporated DCNC-reinforced CMC/PVA films for strawberry preservation.