Preparation, characterization and application of antimicrobial pectin-konjac glucomannan composite films incorporating cellulose nanocrystals stabilized clove essential oil pickering emulsion

In this study, cellulose nanocrystals (CNCs) stabilized clove essential oil (CEO) Pickering emulsions (PE) were utilized to activate polysaccharide films based on pectin (PEC) and konjac glucomannan (KGM). Effects of emulsion dosage (0-15 wt%) on structural, physical and functional properties of the composite films were systematically investigated. Additionally, the application of film coating on grape preservation was explored. Results showed that CNCs stabilized CEO loaded PE (CCPE) exhibited an average size of 674.7 nm and demonstrated excellent physical stability. The results obtained from rheological and FTIR analyses suggest the potential existence of hydrogen bond interactions among the components of the film. SEM observation revealed the good dispersivity of CCPE within the PEC/KGM matrix at an appropriate amount. Overall, compared with control film, the incorporation of CCPE not only improved mechanical and water barrier properties, but also enhanced antimicrobial activities of the PEC/KGM films. Composite film containing 10 wt% CCPE was found to have a highest tensile strength of 23.58 MPa and a lowest water vapor permeability of 1.05 × 10 −10 g/m·s·Pa, along with significant inhibition zone diameters of 38.77 mm and 29.03 mm respectively against S. aureus and E. coli . Notably, CCPE could further slow down the release rate of CEO from composite films as confirmed by the controlled release experiments. When applied to grape preservation, the film coating with 10 wt% CCPE was found to potentially delay postharvest grape senescence and maintain quality attributes during a 15-day storage period at 25°C. • Cellulose nanocrystals stabilized clove essential oil Pickering emulsion (CCPE) was gained. • Antibacterial pectin/konjac glucomannan composite films containing CCPE were developed. • Incorporation of 10% CCPE increased tensile strength by 51.54% and reduced water vapor permeability by 39.04% of the films. • Film with CCPE (10 wt%) exhibited sustained release properties and fresh-keeping effect of grapes during 15-day storage at 25°C.