Boric Acid Crosslinked Polyvinyl Alcohol/Cellulose Nanofiber Nanocomposite Wrapping Films for the Preservation of Vegetables

The short shelf life of fruits and vegetables is a major challenge in the global food supply chain. The current study proposes a solution for preserving fruits and vegetables using biodegradable wrapping instead of conventional plastic wrapping films. PVA nanocomposite films have been prepared using boric acid (BA) as the crosslinking agent and cellulose nanofiber (CNF) extracted from waste onion skin as a nanofiller. The PVA‐BA‐CNF nanocomposite films were evaluated for their morphology, UV shielding and mechanical properties. Morphological studies reveal that the nanocomposite films have a crack‐free rough surface resulting from a combined effect of cross‐linking with BA and dispersion of CNF. The UV–visible spectroscopy results confirmed that the CNF helped significantly to reduce the UV transmittance of PVA‐BA‐CNF, thereby enhancing the UV shielding properties of the film. Whereas the structural reinforcement was enhanced, a compromise in ductility was noted in the PVA‐BA‐CNF nanocomposite films. Further, the quality of the films for preserving fruits and vegetables was tested using a water vapour transmission study, weight loss analysis and antibacterial study. The PVA‐BA‐CNF nanocomposite films showed the lowest water vapour transmission rate (WVTR), especially at high BA content (8 phr), compared to PVA and PVA‐BA films, indicating enhanced moisture barrier performance suitable for packaging. The PVA‐BA‐CNF films showed superior antibacterial activity with 42.84% inhibition against Escherichia coli , due to the formation of a borate–CNF complex in addition to BA‐induced inhibition. It was also found that the PVA‐BA‐CNF wrapping film extended the shelf life of tomatoes compared to unwrapped tomatoes. Hence, the current research contributes towards sustainable food packaging films with excellent UV‐blocking, mechanical, barrier and antibacterial performance.