Natural Biopolymer-Based Nanocomposite Films for Packaging Applications

Abstract

Concerns on environmental waste problems caused by non-biodegradable petrochemical-based plastic packaging materials as well as the consumer's demand for high quality food products has caused an increasing interest in developing biodegradable packaging materials using annually renewable natural biopolymers such as polysaccharides and proteins. Inherent shortcomings of natural polymer-based packaging materials such as low mechanical properties and low water resistance can be recovered by applying a nanocomposite technology. Polymer nanocomposites, especially natural biopolymer-layered silicate nanocomposites, exhibit markedly improved packaging properties due to their nanometer size dispersion. These improvements include increased modulus and strength, decreased gas permeability, and increased water resistance. Additionally, biologically active ingredients can be added to impart the desired functional properties to the resulting packaging materials. Consequently, natural biopolymer-based nanocomposite packaging materials with bio-functional properties have a huge potential for application in the active food packaging industry.

In this review, recent advances in the preparation of natural biopolymer-based films and their nanocomposites, and their potential use in packaging applications are addressed.

Keywords:

• natural biopolymer
• nanocomposite
• solvent casting
• films
• bionanocomposite
• packaging
• active packaging
• antimicrobial packaging

ACKNOWLEDGEMENTS

Support from the Korea Science and Engineering Foundation (Grant No.: R01-2004-000-10389-0) is gratefully acknowledged.

Notes

¹⁾Means ± standard deviations. (E: Young's modulus of elasticity; TS: tensile strength; E _b : elongation at break) (Adapted from Dean and Yu, 2005).

¹⁾Means of three replicates ± standard deviation. Any two means in the same column followed by the same letter are not significantly (P > 0.05) different by Duncan's multiple range tests. (Adapted from Rhim et al., 2005).

²⁾O-MMT: organically modified montmorillonite.

¹⁾Means of three replicates ± standard deviation. Any two means in the same column followed by the same letter are not significantly (P > 0.05) different by Duncan's multiple range test. (Adapted from Rhim et al., 2005).

²⁾O-MMT: organically modified montmorillonite.

¹⁾Means of three replicates ± standard deviation. Any two means in the same column followed by the same letter are not significantly different (P > 0.05) by Duncan's multiple range test. (L, a, b: Hunter L, a, b values; ΔE: total color difference; T ₆₆₀: transmittance at 660 nm, MMT: montmorillonite) (Rhim et al., unpublished data).

¹⁾Means of three replicates ± standard deviation. Any two means in the same column followed by the same letter are not significantly different (P > 0.05) by Duncan's multiple range test. (TS: tensile strength; E _b : elongation at break; E: Young's modulus of elasticity; MMT: montmorillonite) (Rhim et al., unpublished data).

¹⁾Means of three replicates ± standard deviation. Any two means in the same column followed by the same letter are not significantly different (P > 0.05) by Duncan's multiple range test. (MC: moisture content; WVP: water vapor permeability; RH₁: actual relative humidity value underneath the film covering the WVP measuring cup; CA: contact angle of water drop; WS: water solubility; MMT: montmorillonite) (Rhim et al., unpublished data).

¹⁾ −: no inhibition, ± : not clear, +: clear zone of 6–8 mm, ++: clear zone of 8–10 mm.

²⁾Culture medium: TSA(tryptic soy agar, Difco Lab.), incubation temperature: 37°C.

³⁾Ag-Ion₅, Ag-Ion₂₀ : Ag-Ion concentration, 5 and 20% (w/w of chitosan), respectively. MMT: montmorillonite.