Preparation and characterization of a dialdehyde starch crosslinked feather keratin film for food packaging application

Feathers, a byproduct of the poultry industry, have long been considered as a solid waste, posing a series of environmental and economic problems. However, feather keratin (FK) extracted from feathers is a valuable source of the biodegradable and biocompatible polymer. The aim of this study was to develop and characterize novel casting films based on feather keratin (FK) crosslinked by dialdehyde starch (DAS) and plasticized with glycerol for applications in biomedicine. The microstructure, crystallization behavior, light transmission, moisture content, solubility, tensile properties, water vapor barrier property, and cytotoxicity of the FK-DAS films were investigated. The fracture surface of the crosslinked film showed a more compact microstructure than that of the control film, and the crosslinked films were completely amorphous and very transparent (transparency value <2). These results indicate that the addition of DAS increased the transparency value and moisture content and decreased the solubility, indicating the crosslinking between the FK and DAS. The films with 2% DAS showed increased tensile elongation and water vapor permeability compared to the control films, whereas the tensile strength of the film decreased, most probably because the crosslinking effect was counterbalanced by the plasticization of DAS. DAS increased the water resistance of the FK films, thus expanding their potential application in food packaging.