Preparation and characterization of chitosan/HP-β-cyclodextrins composites with high sorption capacity for carvacrol.

The aim of this work was to design new polymer-based systems exhibiting an adjustable loading capacity of carvacrol depending on the film formulation. For this purpose, biocomposite films were developed employing chitosan (CS) as the polymer matrix and hydroxypropyl-β-cyclodextrins (HP-βCDs) as an adjuvant to improve the sorption of carvacrol in the polymer matrix. The morphology, optical, mechanical and barrier properties of the resulting films were investigated, and the sorption capacity of carvacrol evaluated. Biocomposites resulted highly transparent with higher mechanical resistance and moisture barrier properties. Sorption of carvacrol was greatly affected by the humidity (RH) and glycerol (G) content of the biocomposites. The highest sorption values were achieved for composites incorporating 35% glycerol and conditioned at 75% these composites retained 216% carvacrol (g/100 g dry matter). These results indicate that inclusion of carvacrol in the films could be occurring by mechanisms other than formation of inclusion complexes.