Valorization of apple waste for active packaging: multicomponent polyhydroxyalkanoate coated nanopapers with improved hydrophobicity and antioxidant capacity

Bacterial cellulose-based nanopapers (NPs) with improved hydrophobicity and antioxidant capacity were developed for potential active packaging applications. Nanopapers were coated with an hydrophobic medium-chain-length polyhydroxyalkanoate (mcl-PHA) with elastomeric properties. The hydrophobicity and transparency of the obtained films were significantly enhanced with the incorporation of the PHA coating. Additionally, PHA coatings with different amounts of apple extracts (e) with antioxidant capacity were added to the nanopapers (NP/PHA-e). NP/PHA-e films resulted to be much more hydrophobic than the neat nanopapers and the oxygen permeability of the films decreased with the presence of extracts. Finally, the antioxidant capacity of the films was analyzed and the incorporation of apple extracts to the PHA coating provided antioxidant capacity to the films. All the materials used for the preparation of these active films, bacterial cellulose, PHA and extracts, have been obtained from cider by-products, leading to the valorization of this waste.