Fabrication of novel pullulan/carboxymethyl chitosan-based edible film incorporated with ultrasonically equipped aqueous zein/turmeric essential oil nanoemulsion for effective preservation of mango fruits

This study aimed to develop ultrasonically-assisted, alcohol-free, and noncorrosive aqueous zein/turmeric essential oil (TEO)-loaded nanoemulsions (NEs) to stimulate pullulan/carboxymethyl chitosan (P/CMCS)-based edible films for mango fruit preservation. The influence of innovative sonicated zein/TEO-based NEs (ZTNEs) as nanofillers on the physico-mechanical characteristics of the resulting P/CMCS edible films was investigated. A stable and well-dispersed ZTNE was achieved using 20 % zein with 10 min of ultrasound treatment, leading to a reduced droplet size (194.23 ± 0.41 nm) and high ζ-potential (-48.72 ± 0.74 mV). Furthermore, the homogeneity of the ZTNE dispersion, evaluated via confocal laser microscopy (CLSM) analysis, indicated that it can be uniformly incorporated into P/CMCS edible films. In addition, the incorporation of ZTNE into P/CMCS edible films improved barrier properties, mechanical strength, oxidative stability, and antimicrobial properties compared with P/CMCS edible films without ZTNE, possibly due to hydrogen bonding in the film matrix, as confirmed by scanning electron microscopy (SEM) micrographs as well as Fourier transform infrared spectroscopy and X-ray diffraction. Interestingly, the results indicated that P/CMCS/ZTNE/US 10 min and P/CMCS/ZTNE 4 % films demonstrated substantial antibacterial activity against Escherichia coli (11.54 ± 0.72 and 16.62 ± 1.13 mm, respectively) and Staphylococcus aureus (12.81 ± 1.03 and 14.13 ± 0.69 mm), respectively. Moreover, P/CMCS/ZTNE/US 10 min and P/CMCS/ZTNE 4 % films were found to be effective in mango preservation over a 12-day storage period at 25 °C ± 1 °C, as assessed by fruit firmness, weight loss, total soluble solid content, total phenolic content, lipoxygenase activity, and electronic nose analysis. Consequently, these findings indicate that P/CMCS/ZTNE edible films may function as an effective biodegradable packaging solution for fruit preservation within the food industry.