Nanocomposites and their application in antimicrobial packaging

Abstract

The advances in nanocomposites incorporating bioactive substances have the potential to transform the food packaging sector. Different nanofillers have been incorporated into polymeric matrixes to develop nanocomposite materials with improved mechanical, thermal, optical and barrier properties. Nanoclays, nanosilica, carbon nanotubes, nanocellulose, and chitosan/chitin nanoparticles have been successfully included into polymeric films, resulting in packaging materials with advanced characteristics. Nanostructured antimicrobial films have promising applications as active packaging in the food industry. Nanocomposite films containing antimicrobial substances such as essential oils, bacteriocins, antimicrobial enzymes, or metallic nanoparticles have been developed. These active nanocomposites are useful packaging materials to enhance food safety. Nanocomposites are promising materials for use in food packaging applications as practical and safe substitutes to the traditional packaging plastics.

Keywords: active packaging; bioactive molecules; food packaging; nanofiber; nanomaterial; nanostructures.

FIGURE 1

Applications of nanotechnology in the food packaging sector. Nanoclays, nanowhiskers and carbon nanotubes are used for reinforcement purposes improving barrier, mechanical and thermal properties of polymeric films. Active packaging is developed by including metallic nanoparticles and/or nanostructured antimicrobials and antioxidants to provide enhanced shelf life though antimicrobial and oxygen scavenging properties. Intelligent packaging is developed by including nanosensors and nanobarcoding as freshness indicators, gas and oxygen sensors and time-termperature integrators.

FIGURE 2

Schematic representation of different strategies for incorporation of antimicrobial nanoparticles into food packaging materials. (A) Nanoparticles can be incorporated in polymeric films by casting or thermal methods. (B) Grafting of antimicrobial nanoparticles can be achieved after surface modification through pure wet chemistry, irradiation or plasma pretreatment. (C) Antimicrobial nanocomposite coatings by plasma deposition.

FIGURE 3

Different strategies for incorporation of nisin into active food packaging. Nisin can be embedded into different polymeric matrixes or grafted on the surface of modified film surface. Nisin can be also encapsulated into nanoparticles or adsorbed onto inorganic nanostructures, such as clays, before incorporation in composite films.

FIGURE 4

Use of a combination of free and nanoencapsulated antimicrobial substance as active food packaging for extended shelf life.

FIGURE 5

Different strategies to incorporate antimicrobial substances onto nanofibers intended for packaging applications. Antimicrobial substances can be loaded on the surface of nanofibers by (A) physical adsorption or (B) grafting to surface of functionalized nanofibers. (C) Antimicrobial substances encapsulated into liposomes or polymeric nanoparticles can be embedded within or adsorbed onto nanofibers. (D) Loading of antimicrobials can be achieved via layer-by-layer assembly often using polyelectrolytes.

FIGURE 6

Schematic representation of multilayer packaging film. Different film layers can be incorporated with nanostructures presenting different functionalities.