Multifunctional and Nanoreinforced Polymers for Food Packaging

José-María Lagarón

• Publisher: Woodhead Publishing
• Year: 2011
• ISBN:
  9780857092786
• Topic: Design
• Subtopic: Industrial Design

Recent developments in multifunctional and nanoreinforced polymers have provided the opportunity to produce high barrier, active and intelligent food packaging which can help ensure, or even enhance, the quality and safety of packaged foods. Multifunctional and nanoreinforced polymers for food packaging provides a comprehensive review of novel polymers and polymer nanocomposites for use in food packaging.After an introductory chapter, Part one discusses nanofillers for plastics in food packaging. Chapters explore the use of passive and active nanoclays and hidrotalcites, cellulose nanofillers and electrospun nanofibers and nanocapsules. Part two investigates high barrier plastics for food packaging. Chapters assess the transport and high barrier properties of food packaging polymers such as ethylene-norbornene copolymers and advanced single-site polyolefins, nylon-MXD6 resins and ethylene-vinyl alcohol copolymers before going on to explore recent advances in various plastic packaging technologies such as modified atmosphere packaging (MAP), nanoscale inorganic coatings and functional barriers against migration. Part three reviews active and bioactive plastics in food packaging. Chapters investigate silver-based antimicrobial polymers, the incorporation of antimicrobial/antioxidant natural extracts into polymeric films, and biaoctive food packaging strategies. Part four examines nanotechnology in sustainable plastics with chapters examining the food packaging applications of polylactic acid (PLA) nanocomposites, polyhydroxyalkanoates (PHAs), starch-based polymers, chitosan and carragenan polysaccharides and protein-based resins for packaging gluten (WG)-based materials. The final chapter presents the safety and regulatory aspects of plastics as food packaging materials.With its distinguished editor and international team of expert contributors Multifunctional and nanoreinforced polymers for food packaging proves a valuable resource for researchers in packaging in the food industry and polymer scientists interested in multifunctional and nanoreinforced materials.

• Provides a comprehensive review of novel polymers and polymer nanocomposites for use in food packaging
• Discusses nanofillers for plastics in food packaging including the use of passive and active nanoclays and hidrotalcites and electrospun nanofibers
• Investigates high barrier plastics for food packaging assessing recent advances in various plastic packaging technologies such as modified atmosphere packaging (MAP)

1

Multifunctional and nanoreinforced polymers for food packaging

J.-M. Lagarón, Novel Materials and Nanotechnology Group, IATA-CSIC, Spain

Abstract:

The packaging industry has been implementing at a rapidly expanding rate the number of packaging elements made of plastics over recent decades. Plastics, in contrast to more traditional packaging materials like glass and metals, (1) are permeable to the exchange of low molecular weight compounds such as gases and vapours, (2) undergo sorption, so-called scalping, of packaged food constituents, and (3) are amenable to migration into foodstuffs of packaging constituents. Despite these drawbacks, the availability of shapes and forms in which plastics can be conformed, their ease of processing and handling, their low price, their excellent chemical resistance, etc., have made them very attractive in packaging applications. Consequently, a lot of industrial and academic research has been devoted to understanding the mechanisms of mass transport in polymers in order to design new materials and composites with balanced physical properties in general and with improved barrier properties in particular, and to add additional functionalities which may take advantage of their permeability characteristics to positively actuate on the product. This chapter first highlights the factors that make polymers become more impermeable, putting special emphasis on nanotechnology approaches, and then reviews some of the general advances made in the field.

Key words

nanotechnology

high barrier polymers/plastics

biopolymers/bioplastics

packaging

food technology

transport properties

1.1 Introduction

1.1.1 High barrier concept

High barrier is without doubt a highly desirable property of polymeric materials intended to be used in many packaging applications. The term high barrier usually refers to the low to very low permeability of a material to the transport of low molecular weight chemical species, like gases and vapours. Usually, the lower-limit definition for high barrier typically refers to the performance of PET polymers. However, this property has perhaps never attracted so much attention from industry as over the last decades, when it began to be pursued by some modern food and beverage packaging technologies making use of plastic materials.^1–3 In this respect, high barrier has attracted a great deal of recent attention from industry as it has become associated with primary objectives such as commercialization of perishable foods far away from their origin, food shelf-life extension and maintaining food quality and safety. Furthermore, it has also become very relevant to a number of other applications including gas separation membranes, packaging of healthcare products, pharmaceuticals and chemicals, and housing of fuels and oxygenated fuels in fuel tanks and lines in the automotive field.

The reason for the more recent interest in the development of high barrier polymers and polymer-based structures rests on a widespread trend to implement polymeric materials in an ever-increasing number of applications, in many cases aiming to substitute them for other, more traditional packaging materials. It is common knowledge that the attractiveness of plastics lies in their versatility and ability to offer a broad variety of properties and yet be cheap and easily processed and conformed into a myriad of shapes and sizes. However, polymers do have a number of limitations for certain applications when compared with more traditional materials like metals and alloys or ceramics. Among some of these limitations relevant to the purpose of this chapter are their permeability and comparatively low thermal resistance, and the strong interdependence between these two properties. The permeability of plastics to the exchange of gases and vapours imposes a number of challenges in those applications where high barrier, ideally impermeability, is required. These applications were, for instance, traditionally assumed by tinplate and glass in the food packaging field. However, polymer scientists, engineers and technologists in industry and academia have pulled together a great deal of effort and resources to push the limits of plastics performance towards impermeability, chiefly due to the overwhelming pressure exerted by the numerous other advantages associated with the use of plastics in high barrier applications.

Table 1.1 gives typical oxygen permeability and water permeability values for a number of commercial polymers and structures used in food packaging applications.⁴

Table 1.1

Water permeability (at 38 °C and 90% RH) and oxygen permeability (at 23 °C) of a number of commercial plastics and multilayer structures

1.1.2 Functional packaging

The concept of functional or active/bioactive/intelligent packaging for food applications has been recently exploited, obtaining for the package an active role in the preservation, health-promoting capacity and provision of information concerning the products. Among these, active packaging is perhaps the area that has steered more research and industrial interest. Packages may be termed active when they perform some desired role in food preservation other than providing an inert barrier to external conditions. The opportunity of modifying the inner atmosphere of the package or even the product by simply incorporating certain substances in the package wall has made this group of technologies very attractive, representing an increasingly productive research area. Even though the first active packaging developments and most of the commercialized technologies consist of sachet technologies, which make use of a small permeable pouch (sachet) containing the active compound that is inserted inside the package, current trends tend towards the incorporation of active ingredients directly into the packaging wall. This strategy is associated with a number of advantages, such as reduction in package size, higher effectiveness of the active principles (which are now completely surrounding the product), and, in many cases, higher throughput in packaging production, since the additional step of incorporating the sachet is eliminated.⁷ Polymers, and in particular biomass-derived polymers, are the preferred materials for active packaging because of their intrinsic properties, constituting an ideal carrier for active principles, with the advantage of being tuneable in terms of controlled release and the possibility of combining several polymers through blending or multilayer extrusion to tailor the application.

Active packaging has been used with many products and is under investigation for numerous others. These new food packaging technologies have been developed as a response to trends in consumer preferences towards mildly preserved, fresh, tasty, healthier, and convenient food products with prolonged shelf-life. These novel packaging technologies can also be used to compensate for shortcomings in the packaging design, for instance in order to control the oxygen, water or carbon dioxide levels in the package headspace. In addition, changes in retail practices, such as globalization of markets resulting in longer distribution distances, present major challenges to the food packaging industry, which finally act as driving forces for the development of new and improved packaging concepts that extend shelf-life while maintaining the safety, quality and health aspects of the packaged foods. The combinations of polymers and active substances that can be studied for potential use as active packages are in principle unlimited and it is forecast that the number of applications will increase in the near future. Among the existi...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributor contact details
• Preface
• Chapter 1: Multifunctional and nanoreinforced polymers for food packaging
• Part I: Nanofillers for plastics in food packaging
• Part II: High barrier plastics for food packaging
• Part III: Active and bioactive plastics
• Part IV: Nanotechnology in sustainable plastics for food packaging
• Index