Antimicrobial LDPE/EVOH Layered Films Containing Carvacrol Fabricated by Multiplication Extrusion.

Area of Science:

• Materials Science
• Polymer Science
• Food Science

Background:

• Essential oils offer antimicrobial properties but are often unstable during plastic processing.
• Developing effective methods to incorporate sensitive bioactives into polymers is crucial for active packaging.

Purpose of the Study:

• To fabricate antimicrobial multilayered polymeric films containing carvacrol using co-extrusion and microlayering.
• To evaluate the impact of multilayer structure and halloysite nanotubes (HNTs) on carvacrol retention, barrier properties, and antimicrobial efficacy.

Main Methods:

• Co-extrusion and microlayering technique to create up to 65 alternating layers of carvacrol-loaded low-density polyethylene (LDPE) and ethylene vinyl alcohol copolymer (EVOH).
• Carvacrol was either melt-compounded with LDPE or loaded into HNTs prior to film production.
• Characterization of film nanostructure, carvacrol content, barrier properties (oxygen transmission rate), carvacrol release kinetics, and antimicrobial activity against bacteria and fungi.

Main Results:

• Multilayered films retained high carvacrol content despite harsh processing conditions (200 °C).
• Superior barrier properties were observed, with oxygen transmission rates significantly lower than single-layered films.
• Carvacrol diffusivity was over two orders of magnitude lower in multilayered films compared to single-layered films.
• Demonstrated excellent antimicrobial efficacy against *E. coli*, *A. alternata*, and *Rhizopus* in both in vitro assays and a food model (cherry tomatoes).

Conclusions:

• Sensitive essential oils like carvacrol can be successfully incorporated into multilayered plastic films without losing antimicrobial efficacy.
• The developed multilayered films offer a promising approach for creating active packaging with enhanced barrier properties and sustained antimicrobial activity.
• This fabrication method provides a viable strategy for incorporating bio-based antimicrobials into food packaging materials.