Physical, mechanical, and antioxidant properties of alginate/pectin edible films with incorporated chokeberry and wild thyme extracts

Abstract

The purpose of the present study was to develop edible composite films based on sodium alginate and pectin with incorporated Aronia melanocarpa (Michx.) Elliot and Thymus serpyllum L. extracts. The influence of the extracts on the physicochemical, optical, mechanical, and antioxidant properties of the films was investigated. The addition of the extracts changed the colour parameters and significantly increased the barrier properties to UV and visible light. This effect is more pronounced in the film with chokeberry extract and is due to the anthocyanins contained in it (75.43 μg cyd eq•g -1 , cyd eq -cyanidin equivalents). The antioxidant activity of films with incorporated extracts was 4-fold (thyme) to 7-fold (chokeberry) higher than the control alginate/pectin film. A significant improvement in the mechanical characteristics of the films with extracts was found. The values for tensile strength were 9.41 MPa (chokeberry) and 9.54 MPa (thyme), while for the film without extract -4.63 MPa. The resulting films could find potential application as active packaging with antioxidant properties, which could increase the quality and extend the shelf life of the foods packaged in them.