Scalable production of antimicrobial food packaging films containing essential oil-loaded halloysite nanotubes

Abstract

Antimicrobial food packaging holds great promise in extending foods shelf-life and minimizing the risk from foodborne diseases. Specifically, essential oils (EOs) have emerged as promising natural antimicrobials to be incorporated in polymeric materials. Yet, despite the significant research in the field, commercial use of such packaging systems is still in its infancy, due to major barriers, including safety, regulation, benefit-cost ratio, and production capabilities. This work presents industrially viable scale-up production and characterization of antimicrobial low-density polyethylene (LDPE) EOs-containing films, where halloysite nanotubes (HNTs) are employed as functional nanocarriers for EOs. Carvacrol (as a model EO) was loaded into the HNTs nanocarriers and the latter were processed into a masterbatch of LDPE and ethylene vinyl-acetate. The resulting concentrated masterbatch was further diluted and processed into a multilayer film, using a semi-industrial equipment. Carvacrol content in the film was aimed to be low (0.75 wt%) and the produced films displayed a high residual carvacrol content (90 %) in spite of the multiple high-temperature processing steps. Importantly, the resulting films exhibited excellent antifungal efficacy against Penicillium commune, a major food contaminant, in in-vitro micro-atmosphere assays, even after a prolonged storage of 20 months. The film antifungal activity was further studied in two important food systems, bread and fresh cherries, and demonstrated a significant increase of > 73 % in bread shelf-life and 40 % in cherries salability. These results demonstrate that EOs can be incorporated into plastic food packaging systems via industrially viable melt-compounding and extrusion processes, without losing their antimicrobial efficacy. Moreover, we show no migration of HNTs, embedded in the film, into food simulants and address the future perspectives of use of HNTs in food contact materials.