Alginate and pectin films covering halloysite with encapsulated salicylic acid as food packaging components

Abstract

Bionanocomposites containing biopolymers and inorganic nanomaterials of natural origin are intensively studied as eco-firendly alternative to non-biodegradable materials for food packaging applications. The preparation and characterization of pectin and alginate films filled with halloysite (Hal) loaded with salicylic acid are presented here. Two types of Hal with different morphology, derived from Dragon and Dunino mines, were used for adsorption of the antimicrobial agent. The adsorption properties of the nanomaterials were comparable after their initial activation with sulphuric acid. The adsorption increased with increasing initial concentration of salicylic acid. The theoretical analysis of experimental data indicated good correlation with Freundlich isotherm and pseudo-second-order kinetic models. The in vitro release profiles differed depending on the type of biopolymer and the release medium. The release rates were slightly lower for materials with Hal Dunino than those of Hal Dragon in 20% v/v ethanol. Cumulative release was more controlled and prolonged with alginate films, especially in 50% v/v ethanol mimicking food with lipophilic properties. Moreover, alginate films demonstrated greater antimicrobial activity against selected food spoilage bacteria. Alginate materials were effective against four bacteria strains, while pectin films showed the ability of growth inhibition of only two strains tested.