Green active food packaging films based on nanocomposites of PHBV/sepiolite/essential oils†

Abstract

One of the cutting-edge strategies for food packaging is the use of an active storage system, also known as active packaging. In this context, this work aims to evaluate the chemical, physical, and microbiological properties of active poly(hydroxybutyrate-co-hydroxyvalerate)/sepiolite nanocomposite films for application in antibacterial food packaging. In these nanocomposite films, three essential oils (EOs) (oregano – OEO, rosemary – REO, and basil – BEO) with different active compounds were incorporated and their effects were compared. The clay mineral added to the nanocomposites acted as a nucleating agent and enhanced the degree of crystallinity of PHBV, without compromising the thermal stability of the compositions. The EOs exhibited a plasticizing effect on the PHBV matrix with a decrease in the glass transition temperature and elastic modulus, varying according to the type of EO. A slow and controlled release of the EOs under simulated food conditions was also noted, especially for films containing OEO, which was related to the good dispersion of sepiolite nanoparticles in the PHBV matrix that resulted from a combined effect of the clay mineral and OEO. The obtained films exhibited satisfactory antibacterial effects against S. aureus and E. coli bacteria, with a log reduction of more than 2 log cycles. In situ tests in commercial mozzarella cheese for 30 days in the presence of E. coli and L. monocytogenes revealed a lower microbiological count for active films compared to the control film, evidencing the potential of these nanocomposites for application as active packaging in guaranteeing product safety.