Antibacterial mechanism of whey protein isolated-citral nanoparticles and stable synergistic antibacterial eugenol encapsulated Pickering emulsion for grapes preservation.

The purpose of this study was to prepare Pickering emulsion with synergistic antibacterial effect using whey protein isolated-citral (WPI-Cit) nanoparticles with eugenol for grape preservation. In this emulsion, eugenol was encapsulated in oil phase. The particle size, ζ-potential, and antibacterial mechanism of the nanoparticles were characterized. The rheological properties, antibacterial effects and preservation effects of WPI-Cit Pickering emulsion were measured. The results showed that the optimal preparation condition was performed at WPI/Cit mass ratio of 1:1, WPI-Cit nanoparticles were found to damage the cell wall and membrane of bacteria and showed more effective inhibition against S. aureus. Pickering emulsion prepared with WPI-Cit nanoparticles exhibited a better antibacterial effect after eugenol was encapsulated in it, which extended the shelf life of grapes when the Pickering emulsion was applied as a coating. It demonstrated that the Pickering emulsion prepared in this study provides a new way to extend the shelf life.

Quality assurance of postharvest grapes against Botrytis cinerea by terbinafine.

Worldwide, fruit is an indispensable treasure house of nutrition for human beings, occupying a vital position of human diet. Postharvest fruit storage requires efficient antifungal agents to control Botrytis cinerea, which is a vital postharvest disease affecting fruit and leading to enormous losses. However, with the enormous abuse of existing antifungal drugs, the problem of drug-resistant fungi is imminent, making the controlling diseases caused by pathogenic fungi even more challenging. Drug repurposing is an efficient alternative method, we evaluated a well-known antifungal chemical, terbinafine, against the agricultural pathogen, B. cinerea in vitro, as a result, terbinafine showed strong antifungal activity. Furthermore, the in vivo antifungal activity of terbinafine was evaluated, the results showed that terbinafine could reduce the decay area on grapes. Terbinafine could disrupt the cell membrane integrity, increase cell membrane permeability, and eventual cell death of B. cinerea. In addition, terbinafine reduced decay incidence, and weight loss and maintained the soluble solids, titratable acidity, ascorbic acid, total phenolic, and malondialdehyde content during the storage period of grapes. Overall, terbinafine could be an antifungal preservative for postharvest table grapes fresh-keeping.

Chitosan-pullulan films enriched with Artemisia annua essential oil: Characterization and application in grape preservation.

Composite films were prepared using a flow casting method, with chitosan and pullulan as film-forming agents and Artemisia annua essential oil as the UV absorber. The utility of the composite films for preserving grape berries was assessed. The effect of the added Artemisia annua essential oil on the physicochemical properties of the composite film was investigated to determine the optimal amount of essential oil that should be added to the composite film. When the Artemisia annua essential oil content was 0.8 %, the elongation at break of the composite film increased to 71.25 ± 2.87 % and the water vapor transmission rate decreased to 0.378 ± 0.007 g‧mm/(m2‧h‧kpa). The transmittance of the composite film was almost 0 % in the UV region (200-280 nm) and <30 % in the visible light region (380-800 nm), reflecting the UV absorption by the composite film. Additionally, the composite film extended the storage time of the grape berries. Therefore, the composite film containing Artemisia annua essential oil may be a promising fruit packaging material.

Innovative natural antimicrobial natamycin incorporated titanium dioxide (nano-TiO2)/ poly (butylene adipate-co-terephthalate) (PBAT) /poly (lactic acid) (PLA) biodegradable active film (NTP@PLA) and application in grape preservation.

Poly (butylene adipate-co-terephthalate) (PBAT)/polylactic acid (PLA) blended with compatibilizers (polycaprolactone, PCL; poly (ethylene glycol), PEG; titanium dioxide, nano-TiO2) (TP@PLA composites) were developed by melt processing. Natamycin incorporated into TP@PLA blend composites formed NTP@PLA films, which exhibited high tensile strength (24.1-43.5 MPa) and elongation at break (85.8-258.2 %), and exhibited good oxygen permeability, water vapor permeability, surface hydrophobicity and biodegradability. The in vitro results revealed that inhibition of Penicillium expansum cell growth of the NTP@PLA films with addition of 1.0 wt% natamycin reached 95.72 %. The NTP@PLA film with natamycin effectively reduced incidence of decay (1.52 %) on grapes, maintained their quality, and inhibited the growth of pathogenic fungi to up to 0.42 log cfu·g-1. This study generates new insights into the preservation properties of antimicrobial NTP@PLA film, which endow it with great application potential as a novel and eco-friendly packaging material for the food industry.