Kiwi Fruits Preservation Using Novel Edible Active Coatings Based on Rich Thymol Halloysite Nanostructures and Chitosan/Polyvinyl Alcohol Gels

The concept of this study is the replacement of previous fossil-based techniques for food packaging and food shelf-life extension, with novel more green processes and materials following the spirit of circular economy and the global trend for environmentally positive fingerprints. A novel adsorption process to produce thymol-halloysite nanohybrids is presented in this work. The high dispersion of this thymol-halloysite nanostructure in chitosan biopolymer is one of the goals of this study. The incorporation of this biodegradable matrix with poly-vinyl-alcohol produced a very promising food-packaging film. Mechanical, water-oxygen barrier, antimicrobial, and antioxidant properties were measured. Transparency levels were also tested using a UV-vis instrument. Moreover, the developed films were tested in-vivo for the preservation and the extension of the shelf-life of kiwi fruits. In all cases, results indicated that the increased fraction of thymol from thyme oil significantly enhances the antimicrobial and antioxidant activity of the prepared chitosan-poly-vinyl- alcohol gel. The use of the halloysite increases the mechanical and water-oxygen barrier properties and leads to a control release process of thymol which extends the preservation and the shelf-life of kiwi fruits. Finally, the results indicated that the halloysite improves the properties of the chitosan/poly-vinyl-alcohol films, and the thymol makes them further advantageous.

Automated summary

The study aims to replace previous fossil-based techniques for food packaging and shelf-life extension with more environmentally friendly processes and materials in line with the circular economy and global environmental trends. A novel adsorption process is used to produce thymol-halloysite nanohybrids and disperse them in chitosan biopolymer. The incorporation of this biodegradable matrix with poly-vinyl-alcohol produces promising food packaging films with excellent mechanical and barrier properties, as well as antimicrobial and antioxidant activities. The films, when tested in-vivo for preserving and extending the shelf-life of kiwi fruits, showed enhanced preservation effects due to the controlled release of thymol from the nanohybrids.