Antimicrobial and Physical–Mechanical Properties of Polyhydroxybutyrate Edible Films Containing Essential Oil Mixtures

In this study, three different combinations of essential oils (EO) of cinnamon, melaleuca and citronella were incorporated in polyhydroxybutyrate (PHB) films by conventional solution-casting method for food packaging applications. Although melaleuca and citronella EO films have been not demonstrated antimicrobial activity, they presented low UV transmission and high thermal stability. Films containing citronella and cinnamon EO or melaleuca and cinnamon EO, in turn, were active against all tested microorganisms and showed greater flexibility than pure PHB films. Aspergillus niger was the most sensitive microorganism to EO-based polymer films. Overall, the addition of EOs improved the thermal stability of films and reduced the polymer melting temperature as the result of its plasticization, affecting the elastic modulus and elongation at break of films. Taken together, these results suggest that EO-loaded PHB films could be used in designing of biodegradable active packaging for food products.