Effect of design and molecular interactions on the food preserving properties of alginate/pullulan edible films loaded with grape pomace extract

Natural phenolic compounds were extracted from grape and integrated into edible biopolymeric films intended for food preservation. The extract contained mainly catechin, epicatechin and condensed tannins as main phenolic components, and showed promising antioxidant efficacy and a negligible tendency to form clusters. The extract was integrated into alginate/pullulan film-forming dispersions and the inter-molecular interactions were investigated, showing that the biopolymers partially dissolve the phenolic compounds. The characterization of extract-containing films, prepared using a sequential casting method, highlighted the micro-segregation of the phenolic compounds and their functional integration into the composite film in terms of antioxidant and antimicrobial properties. Results show the possibility to tune the food preservation properties of the composite through its multi-layered design, in terms of composition and assembly of each layer, opening new perspectives in the optimal re-use of grape pomace extracts.