Elsevier

Food Research International

Volume 42, Issue 9, November 2009, Pages 1240-1253
Food Research International

Review
Nanocomposites for food packaging applications

https://doi.org/10.1016/j.foodres.2009.03.019Get rights and content

Abstract

Most materials currently used for food packaging are non-degradable, generating environmental problems. Several biopolymers have been exploited to develop materials for eco-friendly food packaging. However, the use of biopolymers has been limited because of their usually poor mechanical and barrier properties, which may be improved by adding reinforcing compounds (fillers), forming composites. Most reinforced materials present poor matrix–filler interactions, which tend to improve with decreasing filler dimensions. The use of fillers with at least one nanoscale dimension (nanoparticles) produces nanocomposites. Nanoparticles have proportionally larger surface area than their microscale counterparts, which favors the filler–matrix interactions and the performance of the resulting material. Besides nanoreinforcements, nanoparticles can have other functions when added to a polymer, such as antimicrobial activity, enzyme immobilization, biosensing, etc. The main kinds of nanoparticles which have been studied for use in food packaging systems are overviewed, as well as their effects and applications.

Introduction

‘‘Nano-’’ denotes nanometer (10−9 m). The concept of nanotechnology was introduced by Richard Feynman in 1959 at a meeting of the American Physical Society (Khademhosseini & Langer, 2006). Since then, nanotechnology has developed into a multidisciplinary field of applied science and technology. Nanotechnology is the ability to work on a scale of about 1–100 nm in order to understand, create, characterize and use material structures, devices and systems with new properties derived from their nanostructures (Roco, 2003). Because of their size, nanoparticles have proportionally larger surface area and consequently more surface atoms than their microscale counterpart. In the nanoscale range, materials may present different electronic properties, which in turn affects its optical, catalytic and other reactive properties (Boccuni et al., 2008, Kahn, 2006).

All biological and man-made systems have the first level of organization at the nanoscale. By using nanotechnology techniques, it is possible to assemble molecules into objects, along several length scales, and to disassemble objects into molecules, as nature already does (Roco, 2003).

Two building strategies are currently used in nanotechnology: a “top-down” approach and the “bottom-up” approach. The commercial scale production of nanomaterials currently involves basically the “top-down” approach, in which nanometric structures are obtained by size reduction of bulk materials, by using milling, nanolithography, or precision engineering. Size usually relates to functionality of food materials, smaller sizes meaning a bigger surface area, desirable for several purposes. The newer “bottom-up” approach, on the other hand, allows nanostructures to be built from individual atoms or molecules capable of self-assembling (Föster and Konrad, 2003, Moraru et al., 2003). Self-assembly relies on balancing attraction and repulsion forces between a pair of molecules as building blocks to form more functional supramolecular structures (Sanguansri & Augustin, 2006).

Nowadays, most materials used for food packaging are practically undegradable, representing a serious global environmental problem. New bio-based materials have been exploited to develop edible and biodegradable films as a big effort to extend shelf life and improve quality of food while reducing packaging waste (Tharanathan, 2003). However, the use of edible and biodegradable polymers has been limited because of problems related to performance (such as brittleness, poor gas and moisture barrier), processing (such as low heat distortion temperature), and cost. Starch, as an example, has received considerable attention as a biodegradable thermoplastic polymer. However, it has a poor performance by itself because of its water sensitivity and limited mechanical properties (Vaidya & Bhattacharya, 1994) with high brittleness, which is related to the anarchical growth of amylose crystals with time (Dufresne & Vignon, 1998). The application of nanotechnology to these polymers may open new possibilities for improving not only the properties but also the cost-price-efficiency (Sorrentino, Gorrasi, & Vittoria, 2007).

Several composites have been developed by adding reinforcing compounds to polymers to enhance their thermal, mechanical and barrier properties. Most of these reinforced materials present poor interactions at the interface of both components. Macroscopic reinforcing components usually contain defects, which become less important as the particles of the reinforcing component are smaller (Ludueña, Alvarez, & Vasquez, 2007).

Polymer composites are mixtures of polymers with inorganic or organic fillers with certain geometries (fibers, flakes, spheres, particulates). The use of fillers which have at least one dimension in the nanometric range (nanoparticles) produces polymer nanocomposites (Alexandre & Dubois, 2000). Three types of fillers can be distinguished, depending on how many dimensions are in the nanometric range. Isodimensional nanoparticles, such as spherical silica nanoparticles or semiconductor nanoclusters, have three nanometric dimensions. Nanotubes or whiskers are elongated structures in which two dimensions are in the nanometer scale and the third is larger. When only one dimension is in the nanometer range, the composites are known as polymer-layered crystal nanocomposites, almost exclusively obtained by the intercalation of the polymer (or a monomer subsequently polymerized) inside the galleries of layered host crystals (Alexandre & Dubois, 2000).

A uniform dispersion of nanoparticles leads to a very large matrix/filler interfacial area, which changes the molecular mobility, the relaxation behavior and the consequent thermal and mechanical properties of the material. Fillers with a high ratio of the largest to the smallest dimension (i.e., aspect ratio) are particularly interesting because of their high specific surface area, providing better reinforcing effects (Azizi Samir et al., 2005, Dalmas et al., 2007, Dubief et al., 1999). In addition to the effects of the nanoreinforcements themselves, an interphase region of altered mobility surrounding each nanoparticle is induced by well dispersed nanoparticles, resulting in a percolating interphase network in the composite and playing an important role in improving the nanocomposite properties (Qiao & Brinson, 2009). According to Jordan, Jacob, Tannenbaum, Sharaf, and Jasiuk (2005), for a constant filler content, a reduction in particle size increases the number of filler particles, bringing them closer to one another; thus, the interface layers from adjacent particles overlap, altering the bulk properties significantly.

Besides reinforcing nanoparticles, whose main role is to improve mechanical and barrier properties of the packaging materials, there are several types of nanostructures responsible for other functions, sometimes providing active or “smart” properties to the packaging system such as antimicrobial activity, enzyme immobilization, biosensing, etc. The most studied nanoparticles will be presented according to their primary functions/applications in food packaging systems. Some particles can have multiple applications, and sometimes the applications can overlap, such as some immobilized enzymes which can act as antimicrobial components, oxygen scavengers and/or biosensors.

Section snippets

Structure, properties and types of composites

Although several nanoparticles have been recognized as possible additives to enhance polymer performance, the packaging industry has focused its attention mainly on layered inorganic solids like clays and silicates, due to their availability, low cost, significant enhancements and relative simple processability. The concept of polymer–clay nanocomposites (PCN) was developed in the late 1980s, and firstly commercialized by Toyota (Collister, 2002), but only since the late 1990s researches have

Antimicrobial nanocomposites

The incorporation of antimicrobial compounds into food packaging materials has received considerable attention. Films with antimicrobial activity could help control the growth of pathogenic and spoilage microorganisms. An antimicrobial nanocomposite film is particularly desirable due to its acceptable structural integrity and barrier properties imparted by the nanocomposite matrix, and the antimicrobial properties contributed by the natural antimicrobial agents impregnated within (Rhim & Ng,

Oxygen scavenging films

Oxygen (O2) is responsible for the deterioration of many foods either directly or indirectly. Direct oxidation reactions result in browning of fruits and rancidity of vegetable oils, to name a few examples. Food deterioration by indirect action of O2 includes food spoilage by aerobic microorganisms. The incorporation of O2 scavengers into food package can maintain very low O2 levels, which is useful for several applications. Attention has particularly focused on the photocatalytic activity of

Nanoscale enzyme immobilization systems

Enzymes are widely used by food industry for several applications. In some cases, the direct use of enzymes can be restricted by their sensitivity to processing conditions and/or to compounds which can inhibit their action, resulting in short operational life or inactivation. When immobilized in different tailored carriers, the enzymes can have improved stability to pH and temperature, resistance to proteases and other denaturing compounds, as well as an adequate environment for their repeated

Final considerations

The use of biopolymers by the food industry has faced feasibility problems related mainly to their relatively high cost and poor overall performance when compared to those of synthetic polymers. However, since industries are concerned with sustainable development, the production cost of biopolymers has decreased, allowing biopolymer-based materials to be increasingly developed. More important, nanocomposites promise to expand the use of edible and biodegradable films, since the addition of

References (206)

  • R.K. Bharadwaj et al.

    Structure-property relationships in cross-linked polyester–clay nanocomposites

    Polymer

    (2002)
  • Y. Bin et al.

    Morphology and mechanical and electrical properties of oriented PVA–VGCF and PVA–MWNT composites

    Polymer

    (2006)
  • F. Boccuni et al.

    Potential occupational exposure to manufactured nanoparticles in Italy

    Journal of Cleaner Production

    (2008)
  • D. Bondeson et al.

    Polylactic acid/cellulose whisker nanocomposites modified by polyvinyl alcohol

    Composites: Part A

    (2007)
  • H. Bouwmeester et al.

    Review of health safety aspects of nanotechnologies in food production

    Regulatory Toxicology and Pharmacology

    (2009)
  • L. Cabedo et al.

    Development of EVOH–kaolinite nanocomposites

    Polymer

    (2004)
  • L. Caseli et al.

    Control of catalytic activity of glucose oxidase in layer-by-layer films of chitosan and glucose oxidase

    Materials Science and Engineering C

    (2007)
  • C. Chawengkijwanich et al.

    Development of TiO2 powder-coated food packaging film and its ability to inactivate Escherichia coli in vitro and in actual tests

    International Journal of Food Microbiology

    (2008)
  • Y. Chen et al.

    Comparative study on the films of poly(vinyl alcohol)/pea starch nanocrystals and poly(vinyl alcohol)/native pea starch

    Carbohydrate Polymers

    (2008)
  • Y. Chen et al.

    Bionanocomposites based on pea starch and cellulose nanowhiskers hydrolyzed from pea hull fibre: effect of hydrolysis time

    Carbohydrate Polymers

    (2009)
  • B. Chen et al.

    Thermoplastic starch–clay nanocomposites and their characteristics

    Carbohydrate Polymers

    (2005)
  • W. Chen et al.

    Enhanced mechanical properties and morphological characterizations of poly(vinyl alcohol)–carbon nanotube composite films

    Applied Surface Science

    (2005)
  • Q. Cheng et al.

    Surface-modified antibacterial TiO2/Ag+ nanoparticles: preparation and properties

    Applied Surface Science

    (2006)
  • V.P. Cyras et al.

    Physical and mechanical properties of thermoplastic starch/montmorillonite nanocomposite films

    Carbohydrate Polymers

    (2008)
  • F. Dalmas et al.

    Viscoelastic behavior and electrical properties of flexible nanofiber filled polymer nanocomposites. Influence of processing conditions

    Composites Science and Technology

    (2007)
  • C. Damm et al.

    The antimicrobial efficacy of polyamide 6/silver-nano- and microcomposites

    Materials Chemistry and Physics

    (2008)
  • S. Dammström et al.

    The effect of moisture on the dynamical mechanical properties of bacterial cellulose/glucuronoxylan nanocomposites

    Polymer

    (2005)
  • M.R. De Moura et al.

    Improved barrier and mechanical properties of novel hydroxypropyl methylcellulose edible films with chitosan/tripolyphosphate nanoparticlses

    Journal of Food Engineering

    (2009)
  • K. Dean et al.

    Preparation and characterization of melt-extruded thermoplastic starch/clay nanocomposites

    Composites Science and Technology

    (2007)
  • A. Fernández et al.

    Perspectives for biocatalysts in food packaging

    Trends in Food Science & Technology

    (2008)
  • C.S.R. Freire et al.

    Composites based on acylated cellulose fibers and low-density polyethylene: effect of the fiber content, degree of substitution and fatty acid chain length on final properties

    Composites Science and Technology

    (2008)
  • A. Fujishima et al.

    Titanium dioxide photocatalysis

    Journal of Photochemistry and Photobiology C: Photochemistry Reviews

    (2000)
  • A. Galdikas et al.

    Response time based output of metal oxide gas sensors applied to evaluation of meat freshness with neural signal analysis

    Sensors and Actuators B

    (2000)
  • S. Gelover et al.

    A practical demonstration of water disinfection using TiO2 films and sunlight

    Water Research

    (2006)
  • S. Gopinath et al.

    Enzymes immobilized on montmorillonite K 10: effect of adsorption and grafting on the surface properties and the enzyme activity

    Applied Clay Science

    (2007)
  • D. Gutiérrez-Tauste et al.

    Characterization of methylene blue/TiO2 hybrid thin films prepared by the liquid phase deposition (LPD) method: application for fabrication of light-activated colorimetric oxygen indicators

    Journal of Photochemistry and Photobiology A: Chemistry

    (2007)
  • D.T. Haynie et al.

    Protein-inspired multilayer nanofilms: science, technology and medicine

    Nanomedicine: Nanotechnology, Biology, and Medicine

    (2006)
  • W. Helbert et al.

    Oriented growth of V amylase n-butanol crystals on cellulose

    Carbohydrate Polymers

    (1994)
  • L. Huang et al.

    Controllable preparation of nano-MgO and investigation of its bactericidal properties

    Journal of Inorganic Biochemistry

    (2005)
  • Z.M. Huang et al.

    A review on polymer nanofibers by electrospinning and their applications in nanocomposites

    Composites Sciences and Technology

    (2003)
  • S.H.D. Hulleman et al.

    Single crystals of V amylose complexed with glycerol

    International Journal of Biological Macromolecules

    (1996)
  • A. Iwatake et al.

    Cellulose nanofiber-reinforced polylactic acid

    Composites Science and Technology

    (2008)
  • W.S. Jang et al.

    Layer-by-layer assembly of thin film oxygen barrier

    Thin Solid Films

    (2008)
  • X. Jia et al.

    Preparation and properties of poly(vinyl alcohol)/silica nanocomposites derived from copolymerization of vinyl silica nanoparticles and vinyl acetate

    European Polymer Journal

    (2007)
  • B. Jiang et al.

    The effect of non-symmetric distribution of fiber orientation and aspect ratio on elastic properties of composites

    Composites: Part B

    (2007)
  • J.H. Johnston et al.

    Nano-structured composite calcium silicate and some novel applications

    Current Applied Physics

    (2008)
  • J. Jordan et al.

    Experimental trends in polymer nanocomposites: a review

    Materials Science & Engineering A

    (2005)
  • J.Y. Kim et al.

    Effect of modified carbon nanotube on the properties of aromatic polyester nanocomposites

    Polymer

    (2008)
  • Y. Kim et al.

    Transparent nanocomposites prepared by incorporating microbial nanofibrils into poly(l-lactic acid)

    Current Applied Physics

    (2009)
  • B. Kim et al.

    Bactericidal effect of TiO2 photocatalyst on selected food-borne pathogenic bacteria

    Chemosphere

    (2003)
  • Cited by (1001)

    View all citing articles on Scopus
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