Antibacterial and antibiofilm activities of nanoemulsion coating prepared by using caraway oil and chitosan prolongs the shelf life and quality of bananas

Abstract

IntroductionBananas are a popular and nutritious fruit that are prone to rapid deterioration and microbial spoilage. Nanoemulsion coatings based on essential oils and chitosan have been proposed as a natural and effective way to preserve the quality and safety of fruits. ObjectivesThe aim of this study was to evaluate the effects of a nanoemulsion coating incorporating caraway essential oil and chitosan (CH-CANE) on the shelf life and attributes of bananas. MethodsThe CH-CANE nanoemulsion was prepared and characterized by DLS (Dynamic Light Scattering), PDI (polydispersity index), ζ potential, whiteness index, and pH. The antibacterial and antibiofilm activities of CH-CANE were tested against Escherichia coli and Salmonella typhi using broth dilution assay and biofilm quantification methods. The quality parameters of banana fruit coated with CH-CANE were measured during 7 days of storage at 25°C, including weight loss, firmness, color, MDA (malondialdehyde) levels, CAT (catalase) and SOD (superoxide dismutase) enzyme activities, total soluble sugar, titratable acidity, and microbial counts. ResultsThe CH-CANE nanoemulsion showed nanometric size (105 ± 8.4 nm), low PDI (0.269 ± 2.7), high ζ potential (+32.43 ± 1.92 mV), high whiteness index (84.39 ± 2.7), and neutral pH (6.8). The CH-CANE nanoemulsion exhibited strong antibacterial and antibiofilm activities against E. coli and S. typhi, with MIC values of 8% and biofilm reduction of 3.5 and 4-log (CFU/ml) under mono and mixed-species culture. The CH-CANE coating significantly improved the quality and safety of bananas during storage, by reducing weight loss, firmness, total soluble sugar, and titratable acidity, maintaining color, increasing antioxidant enzyme activity, and inhibiting microbial growth. ConclusionThe CH-CANE nanoemulsion coating is a promising natural and effective method to extend the shelf life and enhance the attributes of bananas.