Effect of halloysite nanoclay on the physical, mechanical, and antioxidant properties of chitosan films incorporated with clove essential oil

In this study, chitosan (Ch)-based films containing clove essential oil (CEO) as an active agent were developed by incorporating halloysite nanotubes (HNTs) to stabilize the oil droplets. The physical, mechanical, and antioxidant properties of the films were investigated toward their application as food packaging materials. The water vapor barrier property of the films improved upon the addition of the CEO as well as HNTs, owing to the hydrophobicity of the CEO and formation of tortuous pathways by the HNTs. Scanning electron micrographs of films without HNTs showed a large number of micropores on the film surface while few pores were observed on the film surface with the HNTs. Further, the incorporation of CEO decreased the elongation of the film, whereas the HNT particles dispersed in the film matrix mitigated this effect. The antioxidant activity of the films with different concentrations of HNT was determined by total phenolic content, 2,2-diphenyl-1-picrylhydrazyl, and reducing power assays. The highest antioxidant activity was achieved for the Ch/CEO film with 15 wt% HNT. In migration studies, the release of CEO from the film was found to be faster in 50% ethanol (simulant for oil-in-water emulsions and alcoholic foods) than in 10% and 95% ethanol, which are stimulants of aqueous and fatty foods, respectively.