Nanoclays in Food and Beverage Packaging

Hindawi Journal of Nanomaterials Volume 2019, Article ID 8927167, 13 pages https://doi.org/10.1155/2019/8927167 Review Article Nanoclays in Food and Beverage Packaging Nattinee Bumbudsanpharoke and Seonghyuk Ko Laboratory of Nano-Enabled Packaging and Safety, Department of Packaging, Yonsei University, 1 Yonseidaegil, Wonju-si, Gangwon-do 26493, Republic of Korea Correspondence should be addressed to Seonghyuk Ko; Received 12 September 2018; Accepted 12 December 2018; Published 29 January 2019 Academic Editor: Zehra Durmus Copyright © 2019 Nattinee Bumbudsanpharoke and Seonghyuk Ko. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In this study, we present and discuss the technical benefits of using nanoclays as a promising property enhancer in organic polymers for food and beverage packaging. The incorporation of nanoclays can improve the thermal, mechanical, and barrier properties of a host polymer. Both natural hydrophilic and modified organophilic nanoclays provide unique characteristics to the host polymer depending on the selected applications. Besides the advantage of polymer reinforcement, various novel applications of nanoclays in food packaging have been suggested recently, such as control and release for active ingredients, antimicrobial agent, and carrier for the colorimetric indicator system. The existing migration studies discussing the transition from plastic to nanoclay packaging revealed that the diffused level of aluminum and silicon in the nanoclay packaging are within the limitation proposed in Council Directive 90/128/EEC (1990). Therefore, until now, there is no safety restriction in the use of clay nanocomposite films in food packaging applications. 1. Introduction Over the last few decades, food and beverage packaging has progressed enormously because of the diverse consumer demands. The passive role of packaging for logistic and marketing functions has evolved into a smart role for protection, detection, and communication. This paradigm shift in the packaging technology has led to a greater role of packaging in improving the consumers’ health and safety. An active function of packaging has been developed to extend a product’s shelf life by diminishing the incorporate components that would release or absorb substances into or from the packaged food or the environment surrounding the food. Furthermore, an intelligent function has been designed for recording, tracing, and providing information relevant to the changes in quality or conditions of the packed food to the consumers [1, 2]. Recently, an emerging nanotechnology has had a monumental influence on the development of both active and intelligent packaging materials. The research and development of novel hybrid materials with extraordinary properties for food and beverage packaging is one of the most expanding fields in nanoclay application according to a report from Grand View Research Inc. The global nanoclay market for food packaging was the largest segment in 2014, accounting for USD 343.0 million, and is expected to grow significantly through 2022 [3]. Comparing with other nanofillers such as nanosilica [4], calcium carbonate [5], and crystalline cellulose [6], nanoclay shows an equivalent or better performance. Study from Voon et al. [4] showed that halloysite nanoclay provides better mechanical property over nanosilica when blending with bovine gelatin polymer, while barrier properties and water solubility were equally improved. Zare et al. [5] reported that the addition of either nanoclay or calcium carbonate enhance the mechanical strength of the polypropylene film but the required minimum content of each compound is quite different, 2 wt% for nanoclay and 8 wt% for calcium carbonate. Resano-Goizueta et al. [6] reported that the aspect ratio and particle shape of the nanofiller affected the mechanical improvement. The platy morphology of nanoclay confers better mechanical properties to the bio-based polymer than the spherical, cubical, or acicular morphology of the nanocellulose. Moreover, nanoclays are relatively inexpensive and are, in cost-effective terms, reasonable to be employed as a 2 Journal of Nanomaterials 10
휇m 10
휇m 2
휇m 2
휇m (a) (b) 10
휇m 2
휇m (c) Figure 1: SEM micrographs of different types of nanoclays with 3000x and 25000x magnification. (a) Bentonite, (b) Cloisite® 30B, and (c) Nanocor® I.44P. functional material for packaging/container of fast-moving consumer goods, such as food and beverage. The addition of a small amount of nanoclay (<10 wt%) can enhance a host polymer’s barrier, mechanical, thermal, and degradation properties substantially [7, 8]. This review presents a brief overview of nanoclay applications in food and beverage packaging by delving into the unique characteristics of each polymer. Different chemical surface modifications of a nanoclay offer divergent desirable properties, which make it an excellent candidate for use in numerous applications. Further, a recent progress and research on the advanced functions of nanoclays have been introduced in this study to extend the idea of novel applications in the active and intelligent packaging areas. In addition, the possibility of these ultrafine particles migrating from food packaging into food stuff and the perceived potential toxicity induced in humans are also discussed. 2. Nanoclays in Food Packaging Materials Nanoclays possess a characteristic platelet form, flaky soft structure, low specific gravity, and high aspect ratio with nanoscale thickness [9]. Different types of nanoclays are incorporated into the polymers to improve their characteristics. Among these nanoclays, montmorillonite (MMT, MMT-Na+) and organophilic MMT (organic modified MMT, OMMT) have gained most attention in the packaging area, from both academic and industrial researchers, because they possess a high surface area with a fairly large aspect ratio (50–1000) and good compatibility with most of the organic thermoplastics [10, 11]. Figure 1 illustrates the flake-like particles of different types of nanoclays. The agglomerated form is observed in a powder format before being processed with a polymer. In nature, MMT is the determinative component in bentonites, which has a hydrophilic surface. It is miscible with only hydrophilic polymers, i.e., poly vinyl alcohol and polylactic acid. However, most of the food packaging materials are from petroleum-based polymers, such as polyethylene and polypropylene that are hydrophobic in nature. To improve compatibility with an organophilic host matrix, the hydrophilic silicate surface (typically Na+, K+, or Ca+) of a nanoclay must be chemically modified with organic cations (i.e., ammonium salt) through ion-exchange reactions to yield an organophilic surface, which exhibits lower surface energy and higher affinity with the polymer [12] (...truncated)