Sustainable Food Packaging Technology E-Book
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- Sprache: Englisch
Towards more sustainable packaging with biodegradable materials!
The combination of the continuously increasing food packaging waste with the non-biodegradable nature of the plastic materials that have a big slice of the packaging market makes it necessary to move towards sustainable packaging for the benefit of the environment and human health. Sustainable packaging is the type of packaging that can provide to food the necessary protection conditions, but at the same type is biodegradable and can be disposed as organic waste to the landfills in order to biodegrade through a natural procedure. In this way, sustainable packaging becomes part of the circular economy.
?Sustainable Food Packaging Technology? deals with packaging solutions that use engineered biopolymers or biocomposites that have suitable physicochemical properties for food contact and protection and originate both from renewable or non-renewable resources, but in both cases are compostable or edible. Modified paper and cardboard with increased protective properties towards food while keeping their compostability are presented as well. The book also covers natural components that can make the packaging functional, e.g., by providing active protection to the food indicating food spoilage.
* Addresses urgent problems: food packaging creates a lot of hard-to-recycle waste - this book puts forward more sustainable solutions using biodegradable materials
* State-of-the-art: ?Sustainable Food Packaging Technology? provides knowledge on new developments in functional packaging
* From lab to large-scale applications: expert authors report on the technology aspects of sustainable packaging
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Table of Contents
Cover
Title Page
Copyright
Preface
References
Part I: Review on Biopolymers for Food Protection
1 Emerging Trends in Biopolymers for Food Packaging
1.1 Introduction to Polymers in Packaging
1.2 Classification of Biopolymers
1.3 Food Packaging Materials Based on Biopolymers
1.4 Concluding Remarks
References
2 Biopolymers Derived from Marine Sources for Food Packaging Applications
2.1 Introduction
2.2 Fish Gelatin Films and Coating
2.3 Chitosan Films and Coatings
2.4 Future Perspectives and Concluding Remarks
References
3 Edible Biopolymers for Food Preservation
3.1 Introduction
3.2 Polysaccharides
3.3 Proteins
3.4 Lipids
3.5 Edible Composite Materials
3.6 Active Coatings
3.7 Materials Selection and Application
3.8 Conclusions
References
Part II: Food Packaging Based on Individual Biopolymers and their Composites
4 Polylactic Acid (PLA) and Its Composites: An Eco‐friendly Solution for Packaging
4.1 Introduction
4.2 Synthesis of PLA and Its Properties
4.3 Properties Required for Food Packaging
4.4 General Reinforcements for PLA
4.5 Biodegradability of PLA
4.6 Conclusions and Future Prospects
References
5 Green and Sustainable Packaging Materials Using Thermoplastic Starch
5.1 Sustainability and Packaging: Toward a Greener Future
5.2 Thermoplastic Starch
5.3 Thermoplastic Starch‐Based Materials in Packaging
5.4 Conclusions
References
6 Cutin‐Inspired Polymers and Plant Cuticle‐like Composites as Sustainable Food Packaging Materials
6.1 Introduction
6.2 Synthesis of Cutin‐Inspired Polyesters
6.3 Cutin‐Based and Cutin‐like Coatings and Composites
6.4 Concluding Remarks
Acknowledgments
References
7 Zein in Food Packaging
7.1 Introduction
7.2 Solvent Cast Zein Films
7.3 Chemical Characteristics of Solvent‐Cast Zein Films
7.4 Extrusion of Zein
7.5 Zein Laminates with Various Packaging Films
7.6 Zein Blend Films with Other Biopolymers
7.7 Outlook and Future Directions
7.8 Conclusions
References
Part III: Biocomposites of Cellulose and Biopolymers in Food Packaging
8 Cellulose‐Reinforced Biocomposites Based on PHB and PHBV for Food Packaging Applications
8.1 Introduction to Bioplastics
8.2 PHB and PHBV: a SWOT (Strength, Weakness, Opportunity, and Threat) Analysis
8.3 Cellulose Biocomposites
8.4 PHA/Fiber Composites
8.5 Conclusions
References
9 Poly‐Paper: Cellulosic‐Filled Eco‐composite Material with Innovative Properties for Packaging
9.1 Introduction
9.2 Materials
9.3 Mechanical Properties
9.4 Suitable Processes for Poly‐Paper
9.5 Additional Properties of Poly‐Paper
9.6 End‐of‐Life
9.7 Conclusions
References
Notes
10 Paper and Cardboard Reinforcement by Impregnation with Environmentally Friendly High‐Performance Polymers for Food Packaging Applications
10.1 Introduction
10.2 Improving the Barrier Properties of Paper and Cardboard by Impregnation in Capstone and ECA Solutions
10.3 Water, Oil and Grease Resistance of Biocompatible Cellulose Food Containers
10.4 Conclusions
References
11 Nanocellulose‐Based Multidimensional Structures for Food Packaging Technology
11.1 Introduction
11.2 Necessities in Food Packaging Industry
11.3 An Overview of NC
11.4 Cellulose Fibrils and Crystalline Cellulose
11.5 Why NC for Packaging?
11.6 Effect on NCs on Networking
11.7 Migration Process of Molecules Through NC Dimensional Film
11.8 Processing Routes of NC‐based Multidimensional Structures for Packaging
11.9 CNFs for Barrier Application
11.10 CNCs for Barrier Application
11.11 Conclusion
References
Part IV: Natural Principles in Active and Intelligent Food Packaging for Enhanced Protection and Indication of Food Spoilange or Pollutant Presence
12 Sustainable Antimicrobial Packaging Technologies
12.1 Introduction
12.2 Antimicrobial Food Packaging
12.3 Natural Antimicrobial Agents
12.4 Conclusions and Perspectives
References
13 Active Antioxidant Additives in Sustainable Food Packaging
13.1 Introduction
13.2 Antioxidant Capacities of Plant‐Based Food Packaging Materials
13.3 Conclusions and Future Perspectives
References
14 Natural and Biocompatible Optical Indicators for Food Spoilage Detection
14.1 Food Spoilage
14.2 Food Spoilage Detection
14.3 Natural and Biocompatible Optical Indicators for Food Spoilage
14.4 Concluding Remarks and Future Perspectives
References
Part V: Technological Developments in the Engineering of Biocomposite Materials for Food Packaging Applications
15 Biopolymers in Multilayer Films for Long‐Lasting Protective Food Packaging: A Review
15.1 Introduction
15.2 Biopolymer Coatings and Laminates on Common Oil‐Derived Packaging Polymers
15.3 Multilayer Films Based on Proteins
15.4 Multilayer Films Based on Polysaccharides
15.5 Coatings on Biopolyesters
15.6 Summary and Outlook
References
Index
End User License Agreement
List of Tables
Chapter 2
Table 2.1 Fish gelatin‐based active films and coatings.
Table 2.2 Chitosan‐based active films and coatings.
Chapter 3
Table 3.1 Water vapor and oxygen permeability values.
Table 3.2 Polysaccharide‐based edible coatings.
Table 3.3 Cellulose derivatives solubility properties.
Table 3.4 Protein‐based edible coatings.
Table 3.5 Lipid‐based edible coatings.
Table 3.6 Composite edible coatings.
Table 3.7 Active edible coatings.
Chapter 4
Table 4.1 Summary of different research work done on PLA‐composites.
Chapter 5
Table 5.1 Composition of starch from different sources.
Chapter 6
Table 6.1 Main advantages and drawbacks of petroleum‐based plastics.
Table 6.2 Main advantages and drawbacks of the use of biopolymers.
Table 6.3 Main bio‐based, biopolymers, their monomeric units, and main applic...
Table 6.4 Main composition of a generic cutin and specific composition of tom...
Table 6.5 Young's modulus, stress and elongation at break, water contact angl...
Table 6.6 Thermal parameters and crystallinity of references polyhydroxyester...
Table 6.7 Tensile parameters of references polyhydroxyesters films prepared u...
Table 6.8 Static water contact angle values of reference polyhydroxyester fil...
Chapter 7
Table 7.1 Typical wavenumbers of Raman bands and general assignments in prote...
Table 7.2 Surface elemental compositions of zein films prepared from ethanol/...
Table 7.3 Summary of zein blend films with other bio‐based or biodegradable p...
Chapter 8
Table 8.1 Main advantages and disadvantages of lignocellulosic fibers in poly...
Table 8.2 Examples of reactive compatibilization in PHA/fiber composites.
Chapter 9
Table 9.1 Poly‐paper formulations (from 0% to 55% of cellulose fibers content...
Table 9.2 Mechanical parameters obtained from tensile mechanical tests perfor...
Table 9.3 Characteristics (density, expansion factor, and color) based on dif...
Table 9.4 Characteristics (density, expansion factor, and color) for 100 : 0,...
Table 9.5 Adhesive property results of Poly‐Paper 50% coupled with itself, pe...
Chapter 10
Table 10.1 Physical and mechanical properties of untreated and treated papers...
Table 10.2 Comparison of grease resistance properties of paper coated with di...
Table 10.3 Comparison of
oxygen permeability
(
OP
) of treated paper with other ...
Chapter 11
Table 11.1 Oxygen permeability of NC film compared to those made from commerc...
Table 11.2 WVTR of NC compared to commercially available petroleum‐based mate...
Chapter 12
Table 12.1 Main active packaging systems.
Table 12.2 Examples of antimicrobial plant extracts incorporated into bio‐bas...
Table 12.3 Examples of antimicrobial organic acids, their salts and anhydride...
Table 12.4 Examples of bacteriocins incorporated into bio‐based polymer matri...
Table 12.5 Examples of antimicrobial enzymes incorporated into bio‐based poly...
Table 12.6 Examples of chitosan‐based antimicrobial films.
Chapter 13
Table 13.1 Active bioplastic films containing tea and berry extracts.
Table 13.2 Different bioplastic films incorporated with extractions from herb...
Table 13.3 Active packaging compositions and the effect of natural additives ...
Chapter 14
Table 14.1 Overview of common target analytes used for sensing in food safety...
Table 14.2 Commercially available smart packaging systems.
Chapter 15
Table 15.1 Several natural polymer barrier properties and in certain cases in...
Table 15.2 Summary of bi‐ or multilayer food packaging systems made by combin...
List of Illustrations
Chapter 1
Figure 1.1 Classification of biopolymers widely used in packaging.
Figure 1.2 Commercial food packaging articles made of polylactide (PLA): (a)...
Figure 1.3 Biodegradable food tray made of poly(3‐hydroxybutyrate) (PHB) obt...
Figure 1.4 Schematic flow diagram of the production of bio‐based polyethylen...
Figure 1.5 Image of the PlantBottle™ made up to 30% from biomass and 100% re...
Figure 1.6 Biodegradable packaging articles based on starch.
Figure 1.7 Cellulose derivatives categorized based on their pH‐responsive be...
Figure 1.8 Scheme of the gelatin manufacturing from denaturation of collagen...
Figure 1.9 A zein film obtained from corn.
Chapter 2
Figure 2.1 Fishery production, wastage, and possible solutions.
Chapter 3
Figure 3.1 Edible film and coating manufacturing.
Figure 3.2 Sodium alginate manufacturing process.
Figure 3.3 Carrageenan manufacturing process.
Figure 3.4 Time‐lapse of the effect of silk fibroin edible coating on strawb...
Figure 3.5 (a) Time‐lapse photography of silk fibroin coating effect on bana...
Chapter 4
Figure 4.1 Structural formula of PLA.
Figure 4.2 Synthesis of PLA from
L
‐ and
D
‐lactic acids.
Figure 4.3 Properties required for packaging material.
Figure 4.4 Hemp/PLA Co‐wrapped hybrid yarn.
Figure 4.5 Mechanism of enhancement in the interface of ramie and PLA by usi...
Chapter 5
Figure 5.1 General properties required for properties of packaging materials...
Figure 5.2 Classifications of biopolymers.
Figure 5.3 Chemical structure of (a) amylose and (b) amylopectin.
Chapter 6
Figure 6.1 World plastic production 2004–2017.
Figure 6.2 Distribution of plastics demand by segments.
Figure 6.3 Degradation time of selected fuel‐based plastics.
Figure 6.4 Classification of bio‐based, biodegradable polymers based on thei...
Figure 6.5 Schematic representation of a transversal section of the outer pa...
Figure 6.6 Chemical structure of the reference fatty hydroxyesters used.
Figure 6.7 (bottom) Transmission IR spectra of reference polyhydroxyesters o...
Figure 6.8 Solid‐state
13
C NMR of reference polyhydroxyesters prepared in ai...
Figure 6.9 (top) TGA and (bottom) TGA‐derivative profiles of the reference p...
Figure 6.10 Tensile stress‐train curves of the reference polyhydroxyesters p...
Figure 6.11 (a) ATR‐FTIR quantification of the amount of oxidized species at...
Figure 6.12 ATR‐FTIR spectra of the air‐exposed and air‐preserved sides of p...
Figure 6.13 Visual aspect of poly triHPA prepared in air at variable time an...
Figure 6.14 Total transmittance curves of poly triHPA prepared under oxidati...
Figure 6.15 (a) Specular ATR‐FTIR spectra of polyaleuritate films on stainle...
Figure 6.16 (a) Specular ATR–FTIR
ν
(C=O) band fitting pattern for polya...
Figure 6.17 Photographs of the samples of the plant‐cuticle film composites ...
Chapter 7
Figure 7.1 (a) Zein powder extracted from corn. (b) Complete structure of Z1...
Figure 7.2 Biodegradable films produced from different proteins and their bl...
Figure 7.3 (a) The steps of the blown extrusion technique including (1) zein...
Figure 7.4 (a) Ternary phase diagram for the solubility of zein in ethanol a...
Figure 7.5 Different types of zein films solvent cast from DMSO and their sh...
Figure 7.6 Photographs of zein‐glass microfluidic devices with complex fluid...
Figure 7.7 The solid‐state
13
C‐CP‐MAS‐NMR spectra of zeins (Z1) obtained by ...
Figure 7.8 (a) TEM micrograph showing protein in corn gluten meal/starch ext...
Figure 7.9 Rheological properties of powdery zein plasticized with 20 wt% gl...
Figure 7.10 (a) SEM micrograph of the corn–zein‐coated PP film for thickness...
Figure 7.11
Tapping mode atomic force microscopy
(
TPAFM
) images of zein/F127...
Figure 7.12 (a) Confocal light scanning microscopy images of different parts...
Chapter 8
Figure 8.1 General structure of PHAs.
Figure 8.2 Optical micrographs of PHB spherulites showing cracks and fissure...
Figure 8.3 Schematic representation of the three‐phase model and the “contin...
Figure 8.4 Mechanism of thermal degradation of PHAs by cis‐elimination. The ...
Figure 8.5 Schematic representation of the structure of lignocellulosic fibe...
Chapter 9
Figure 9.1 Process parameters (zone temperatures from Z1 to Z8) in relation ...
Figure 9.2 Cross‐sections of the semifinished products obtained from extrusi...
Figure 9.3 The effect of cellulose microfiber content on Young's modulus.
Figure 9.4 (a) Poly‐Paper pellets and (b) Poly‐Paper filled mold.
Figure 9.5 Starting slabs (a) and result thermoformed Poly‐Paper (b) [27]....
Figure 9.6 Poly‐Paper 3D printed samples, flat printed and shaped via heat t...
Figure 9.7 Shortening (%) vs. time (days) of different formulations of Poly‐...
Figure 9.8 Adhesive determination of Poly‐Paper samples to wood and cardboar...
Figure 9.9 Water dissolution kinetics of Poly‐Paper in three different formu...
Figure 9.10 Preliminary test on Poly‐Paper, Aticelca test method mc 501: 201...
Figure 9.11 Preliminary results of Aticelca test on Poly‐Paper, test method ...
Chapter 10
Figure 10.1 Stereo‐micrograph of untreated and treated cardboard with polyme...
Figure 10.2 SEM images of (a) an untreated cellulosic sheet (35‐μm thickness...
Figure 10.3 XPS analysis of untreated and treated cardboard (a) untreated, (...
Figure 10.4 FTIR spectra of untreated cardboard, polymer 1 (capstone) treate...
Figure 10.5 Water drop deposited onto the (a) untreated and fluorinated caps...
Figure 10.6 Water drop deposited onto the internal part of untreated and tre...
Figure 10.7 Image taken after complete dipping of the ECA (5 wt%) treated ca...
Figure 10.8 Water contact angle (WCA) of cardboard 1 (cardboard weight 800–9...
Figure 10.9 Oil contact angle (OCA) of cardboard 1 (cardboard weight 800–900...
Figure 10.10 Water contact angle (WCA) of cardboard 2 (weight 200–500 g/m
2
) ...
Figure 10.11 Water contact angle (WCA) of cardboard 2 (weight 200–500 g/m
2
) ...
Figure 10.12 Moisture content for cardboard 1 (cardboard weight 800–900 g/m
2
Figure 10.13 Moisture content for cardboard 2 (cardboard weight 200–500 g/m
2
Figure 10.14 Mechanical properties of cardboard 1 (cardboard weight 800–900 ...
Figure 10.15 Mechanical properties of cardboard 2 (cardboard weight 200–500 ...
Figure 10.16 Scanning electron microscopy (SEM) analysis of (a, b) untreated...
Figure 10.17 Water and oil droplets remaining trace onto the surface and ben...
Figure 10.18 Water and oil resistance tests of treated paper. (a, b) Water a...
Chapter 11
Figure 11.1 Various processing routes for the production of NC‐based multidi...
Figure 11.2 Various types of NC isolated from wood and bacterial culture. Ac...
Figure 11.3 Gas permeability representation of NC‐based films. Tighter netwo...
Chapter 13
Figure 13.1 Circular economy idea of developing active food packaging from n...
Chapter 14
Figure 14.1 External and internal factors and sensory manifestations of food...
Figure 14.2 Overview of the different sensing portable technologies for on‐s...
Figure 14.3 Colorimetric response to a pH range of 2–14 of (a) anthocyanin i...
Figure 14.4 Application of the anthocyanin treated polyvinyl alcohol/cellulo...
Figure 14.5 (a) Absorption spectra and photographs of paper films impregnate...
Chapter 15
Figure 15.1 Schematic representation of a liquid food product (milk) packagi...
Figure 15.2 (a) Fresh‐cut apples packed in whey protein isolate film and (b)...
Figure 15.3 Naturally occurring biopolymers that can be used in the design, ...
Figure 15.4 (a) Four different classes of bacteria colonization of PG‐coated...
Figure 15.5 Barrier properties of whey‐based layer compared to other plastic...
Figure 15.6 Scanning electron microscopy images of surface morphology of the...
Figure 15.7 (a) Oxygen transmission rates (OTR) values of CZNC–PP films (in ...
Figure 15.8 Soil burial
weight loss
(
WL
) curves of 30 wt% glycerol plasticiz...
Figure 15.9 Schematic illustration of the mechanism for one‐way water barrie...
Figure 15.10 3D AFM images of (a) (PLA), (b) (FG), and (c) multilayer films....
Figure 15.11 (a) Schematic of the LBL deposition process and a simplified im...
Figure 15.12 (a) Layer‐by‐layer coating manufacturing process.. (b) Micr...
Figure 15.13 Visual analysis of (a) tomato and (b) apple chunks packed in a ...
Figure 15.14 (a) Film blowing process of co‐extruded layers of PHBV and PBAT...
Guide
Cover Page
Table of Contents
Begin Reading
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Sustainable Food Packaging Technology
Edited by
Athanassia Athanassiou
Editor
Dr. Athanassia Athanassiou
Italian Institute of Technology
Smart Materials
Via Morego, 30
16163 Genova
Italy
Cover Images
© Andrei Mayatnik / Shutterstock,
© Nelli Syrotynska / Shutterstock
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Preface
There could not be a clearer and at the same time shocking demonstration of our non‐sustainable way of living than the recent COVID‐19 pandemic, which started in late 2019 in Wuhan, China, expanding all over the world in just few months. The occurrence and the extremely rapid expansion are connected to human dietary shifts toward consumption of animal products never used before due to increasing nutrition demand, extraordinary population densities, and unprecedented environmental pollution. The pandemic, its fast spread, and its consequences all over the planet in a very short period made evident that we are living in a closed system, interconnected in ways that are out of our control and we have to face the global problems with common strategies. Sustainable living has become essential, and a global sustainable consciousness must be formed and immediate decisions and actions need to be taken toward this direction.
Sustainability should be radically established in our lifestyle, habits, and actions. The massive use of plastics and their uncontrolled disposal in the last four decades are habits that need to be changed immediately. The uncontrolled production and use of plastic have brought the planet's pollution to levels never seen before. Only in 2018, 359 million metric tons of plastic were produced globally, while a total of about 9.2 billion metric tons were produced between 1950 and 2017. From all this plastic ever produced, it is estimated that about 9% has been recycled, 12% incinerated, and the remaining 79% has ended up in landfills or the environment. For example, it is estimated that 4.8 to 12.7 million metric tons of plastic enter the marine environment every year [1]. Photographs of animals and fish suffocating in their habitats due to dumped plastics, or of extended areas full of plastic garbage, especially from developing countries that have become the waste disposal fields for the developed ones, as well as studies on how toxic chemicals released from wrongly disposed plastics compromise our health are reaching us daily.
The most important source of badly disposed plastic waste is packaging. In 2017, around 15 million metric tons of plastic packaging waste was generated only in the European Union. In the general packaging sector, food packaging has the most important plastic demand. Plastic food packaging production in Europe is 8.2 million tons per year, included in the 20.5 million tons per year production for the general packaging sector and in the 51.2 million tons per year of the total European plastic demand [2]. Its short lifetime and frequent contamination from food makes it the most voluminous, wrongly disposed, plastic waste. For this reason, the introduction of biodegradable‐compostable plastic packaging, either from petrochemical sources or preferably from natural renewable resources, has become mandatory and attracts a great deal of research and industrial interest. This, in combination with the various governmental stringent requirements and incentives related to plastic reduction throughout the planet, makes sustainable food packaging an emerging application area that expectantly will find its way to the market substituting the currently used recalcitrant plastic packaging solutions.
This book deals exactly with this rapidly emerging research and application field of Sustainable Food Packaging. It starts with Part I “Review on Biopolymers for Food Protection.” This part of the book presents review chapters 1, 2, and 3 on the most relevant biopolymers that slowly find their way to the food packaging market, but also on biopolymers that are not yet industrialized (either due to high costs of extraction and transformation in packaging materials or due to lack of investment), but have a great potential due to their unique properties. In particular, Chapter 1 “Emerging Trends in Biopolymers for Food Packaging,” by Sergio Torres‐Giner et al., starts with a detailed and comprehensive introduction to the different types of biopolymers, and their classification according to their origin and biodegradability characteristics. The chapter continues with the presentation of the most important biopolymers that are currently available and describes their origin, chemistry, synthesis/extraction, and/or chemical modification methods. It also positions these biopolymers in the current plastic market and describes their prospects, advantages, and disadvantages in the sector of food packaging. In their concluding remarks, the authors give an expert point of view on where the bioplastic efforts for food packaging should be directed in order to have an important positive future environmental impact. Chapter 2 “Biopolymers Derived from Marine Sources for Food Packaging Applications,” by Jone Uranga et al., presents the two most important biopolymers for food packaging, originating from marine biomass, fish gelatin and chitosan. Regarding gelatin, the chapter describes the extraction methods of collagen by fish waste biomass, and the subsequent production gelatin by partial hydrolysis of collagen. The authors continue with a presentation of the methods of development of gelatin coatings and films as food packaging and their impact on the food shelf life extension. Regarding chitosan, the authors first analyze the extraction methods of chitin by marine biomass, such as crustacean shells and squid pens, before its transformation to chitosan by deacetylation. Finally, the development, properties, and effect on the packaged food life extension are analyzed for the various chitosan coatings and films presented in the literature as food packaging solutions. Chapter 3 “Edible Biopolymers for Food Conservation,” by Elisabetta Ruggeri et al., describes the innovative idea of natural polymeric protective coatings or films for food preservation and freshness extension that can be consumed together with the food, accompanied by the various regulations that would cover such use. The authors analyze the various biopolymers that can be transformed into edible packaging, classifying them as polysaccharides, proteins, lipids, and their mixtures. They present the various ways of development of the films for wrapping or of the coatings applied directly onto the food, their properties, and the possibility to act as matrices for functional additives, like antimicrobial and antioxidant agents. Finally, the authors provide information on the possible limitations and on the future perspectives of natural edible food packaging.
The book continues with Part II “Food Packaging‐Based on Individual Biopolymers and Their Composites,” where the most promising biopolymers and their composites for the food packaging sector are presented separately. Part II describes both the biopolymers that have already found their way to the market together with their future challenges, and the biopolymers that are not yet in the market but due to their unique properties have a good potentiality. Indeed, Chapter 4 “Polylactic acid (PLA) and Its Composites: An Eco‐friendly Solution for Packaging,” by Swati Sharma, describes research advancement related to food packaging based on PLA and its composites, indisputably the most available and promising biopolymer currently present in the market. The chapter starts with the synthetic routes of PLA and continues with the description of its physical properties, emphasizing the ones essential for food packaging materials. Subsequently, the author presents a review on the various fillers, i.e. synthetic and natural fibers or nanoparticles, that have been used to enhance the relevant properties of PLA, and closes the chapter with the current uses in the market and the future perspectives of this exceptional biopolymer. Chapter 5 “Green and Sustainable Packaging Materials using Thermoplastic Starch,” by Anshu Anjali Singh and Maria Erminia Genovese, is dedicated to biocomposites based on thermoplastic starch, a biopolymer with great potentiality for food packaging due to its abundance, biodegradability, and low price, that has already found its way to the market. Although the chapter is dedicated to a specific biopolymer, the authors make an analytical introduction to the plastic threat that has made vital the need of sustainable polymers especially in the food packaging sector, and present the various categories of biopolymers available for this purpose emphasizing on starch. They continue with the presentation of research studies on thermoplastic starch composites developed for packaging applications underlining their most relevant properties, such as mechanical properties, gas and vapor permeability and biodegradability, their processing methods, their possible drawbacks, while they also present the commercially available packaging solutions. Finally, they conclude with the challenges to be addressed and the future developments needed for starch, its composites, and its derivatives in food packaging. Chapter 6 “Cutin‐inspired Polymers and Plant Cuticle‐like Composites as Sustainable Food Packaging Materials,” by Susana Guzman‐Puyol et al., presents the unique biopolymer cutin, the main component of cuticle, which constitutes the outer surfaces of plants and serves as a protective layer from the environment. The authors introduce the dramatic effect of plastics to the environment and the alternative bio‐based and biodegradable biopolymers. They continue with the description of plant cuticle, its natural role, its structure and its composition, where the principle component cutin is introduced. A quantitative comparison of the physical properties of cutin and various biodegradable biopolymers reveals the strong and weak points of the former, and the ways to obtain cutin from its main resource, the tomato pomace, are described. The authors also present scalable techniques for the synthesis of cutin‐inspired polyesters and methods to tune their properties. Finally, the methods to fabricate cutin‐inspired coatings and cuticle‐like composites as protective packaging for food are presented. Chapter 7 “Zein in Food Packaging,” by Ilker S. Bayer, gives an exhaustive presentation of the protein biopolymer, zein, highly promising for food packaging mainly due to its film‐forming capability and hydrophobic properties. Its origin, molecular structure, and general properties are first introduced. The focus of the chapter is on the fabrication methods of zein‐based films and their characterization as food packaging materials. The presented methods are solvent casting, melt extrusion, solvent or melt blending with biopolymers, and lamination, either with other bio‐polymers or petroleum‐based polymeric films. The author closes the chapter with the future perspectives and his point of view on the directions that zein development should follow in order to be a valid candidate for the food packaging industry.
Part III of the book is dedicated to the most abundant natural polymer of our planet, the cellulose, and is entitled “Biocomposites of Cellulose and Biopolymers in Food Packaging.” It presents sustainable composites of biopolymers with cellulose in various forms, with exceptional properties, competitive to the conventional nonbiodegradable plastics, for the food packaging market. In particular, Chapter 8 “Cellulose‐reinforced Biocomposites Based on polyhydroxybutyrate (PHB) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) PHBV for Food Packaging Applications,” by Estefania Lidon Sanchez‐Safont et al., deals with the microbial polymers polyhydroxyalkanoates (PHAs) and discusses how cellulose fibers can improve their properties to make them competitive for the food packaging market. Specifically, the authors analyze separately, first the strengths, weaknesses, opportunities, and threats (SWOT) of two bacterial biopolymers, PHB and PHBV, and subsequently the properties of lignocellulose fibers that make them ideal candidates as reinforcing fillers in composites. Next, they review the research that has been done so far on the combination of PHB and PHBV with various lignocellulose fibers and they present the great potentiality of such composites as food packaging materials, indicating the weak points to be overcome. Chapter 9 “Poly‐Paper: Cellulosic‐filled Eco‐composite Material with Innovative Properties for Packaging,” by Romina Santi et al., focuses on a very interesting patented material, made of cellulose microfibers in the sustainable, water‐soluble poly(vinyl alcohol) (PVA) matrix, with the name Poly‐Paper. Poly‐paper can be very versatile in terms of manufacturing processes and final properties, and as such, can find many ways to enter into the packaging market. Indeed, it can be processed by extrusion, injection molding, and thermoforming, while at the end of life can reenter in the paper recycling chain. Chapter 10 “Paper and Cardboard Reinforcement by Impregnation with Environmentally Friendly High‐performance Polymers for Food Packaging Applications,” by Uttam C. Paul and José A. Heredia‐Guerrero, describes their research on a different approach to cellulose‐based food packaging. Cellulose is not present as micro or nanofiller in a polymer, but in the form of an intact substrate, like paper or cardboard, impregnated with environmentally safe, biocompatible polymers and composites, in order to attain properties that can expand and reinforce its positioning in the food packaging market, without compromising its biodegradable nature. The treatment offers to the cellulose substrates water and oil resistance, resistance to moisture, and mechanical reinforcement, all properties that cellulose lacks intrinsically, so it can be a viable solution to increase its request in the sustainable food packaging market. The book continues with Chapter 11 “Nanocellulose‐Based Multidimensional Structures for Food Packaging Technology,” by Saumya Chaturvedi et al., which deals with nanocellulose‐based food packaging solutions. The authors present an overview of the different kinds of nanocellulose, which include fibrils or crystallites with at least one dimension in the nanoscale range, and their properties depending on the origin, i.e. plants or bacteria, and the isolation methods. The chapter proceeds with the ways that nanocellulose, alone or combined with polymers, forms various compact structures that can be used for packaging. Finally, the authors focus on two types on nanocellulose, the cellulose nanofibers and the cellulose nanocrystals, emphasizing their differences and reporting the research that was done so far on their freestanding films either alone or as polymer fillers, comparing them with conversional plastics films used in the food packaging sector.
A book on Sustainable Food packaging could not be complete without Part IV dedicated to “Natural Principles in Active and Intelligent Food Packaging for Enhanced Protection and Indication of Food Spoilage or Pollutant Presence,” since sustainability is closely related to the extension of the shelf life of food and the prevention of food waste. Wasting food is economically nonviable, not ethical, and drains the already very limited natural resources. Chapter 12 “Sustainable Antimicrobial Packaging Technologies,” by Yildirim Selçuk and Bettina Röcker, presents advancements in the use of bioactive substances combined within biopolymers from renewable resources as protective food packaging with antimicrobial action against foodborne pathogens and spoilage microorganisms. The authors introduce the concept of active packaging, its different categories, and specific actions, with a dedicated section on the antimicrobial active packaging, its classes, research advances, and regulations. Then, they analyze separately the most studied natural antimicrobial agents, i.e. essential oils and phenolic compounds; organic acids, their salts and anhydrides; bacteriocins and enzymes; and the antimicrobial polymer chitosan, with references of their use as active additives in packaging of food systems. The authors conclude their chapter with the strategies needed for a successful and rapid introduction of active sustainable antibacterial packaging in the food packaging industry. Chapter 13 “Active Antioxidant Additives in Sustainable Food Packaging,” by Thi Nga Tran, deals also with active packaging but in this case with antioxidant activity. The author starts with an introduction to the urgent need of a significant reduction of food losses and wastes, and how protection from oxidation, using packaging systems of biopolymers combined with natural antioxidant substances, could help. The chapter continues with a detailed analysis of the various antioxidant molecules extracted by plants, their combination with biopolymers into active food packaging, and the properties of the obtained packaging systems, including, of course, their antioxidant activity. A particular mention is made to the possibility of using raw dried plants powders, even from agricultural by‐products, as antioxidant fillers into biopolymers for the development of active sustainable food packaging, avoiding the extraction costs. Part IV of the book ends with Chapter 14 “Natural and Biocompatible Optical Indicators for Food Spoilage Detection,” by Maria E. Genovese et al., which presents another very interesting approach in food waste prevention. The authors describe packaging materials with incorporated natural or biocompatible molecules that change their molecular structure, and thus their optical properties, in the presence of food spoilage. Consequently, when a specific food spoilage by‐product is present, the active packaging changes one or more optical properties (i.e. color, spectral absorption, fluorescence) enabling a real‐time and direct naked eye spoilage detection. The authors introduce the factors determining food spoilage, and analyze thoroughly the conventional methods, as well as the most recent portable technologies for on‐site and on‐package detection of the spoilage, together with the functioning principles of these technologies. Then, the authors focus on the description of the various functional components used for the optical and colorimetric spoilage indication usually embedded in a polymeric, most of times natural renewable, support, as well as the specific spoilage by‐product they can detect. A particular emphasis is given on the sensing potential of natural dyes and pigments extracted from plants, i.e. curcumin and anthocyanins, as well as their synthetic counterparts, due to their eco‐friendly nature.
The book closes with Part V “Technological Developments in the Engineering of Biocomposite Materials for Food Packaging Applications,” where Chapter 15 “Biopolymers in Multilayer Films for Long Lasting Protective Food Packaging: A Review,” by Ilker S. Bayer, presents the possibilities that technology provides to take advantage of the various biopolymers and composites combining them in unique solutions for food packaging. Apart from melt extrusion, injection molding, blow molding, and thermoforming, all techniques used broadly in the plastic industry and mentioned in the various chapters of this book, Chapter 15 describes the ways of making multilayer films that can combine the unique properties of the various biopolymer layers into one material. The chapter reviews both multilayer laminates of biopolymers with conventional oil‐derived polymers and all sustainable laminates, based on proteins, polysaccharides, or biopolyesters. The author concludes that multilayer laminates of carefully chosen biopolymers and biocomposites could be the ideal materials for food packaging since they combine sustainability with optimized desired properties due to their unique construction.
Athanassia Athanassiou
Genova, Italy
29 September 2020
References
1 Jambeck, J.R., Geyer, R., Wilcox, C. et al. (2015). Plastic waste inputs from land into the ocean.
Science
: 768–771.
2 Data for the year 2018 From ING Economics Department and
https://www.statista.com/statistics/282732/global-production-of-plastics-since-1950
.
Part IReview on Biopolymers for Food Protection
1Emerging Trends in Biopolymers for Food Packaging
Sergio Torres‐Giner, Kelly J. Figueroa‐Lopez, Beatriz Melendez‐Rodriguez, Cristina Prieto, Maria Pardo‐Figuerez, and Jose M. Lagaron
Novel Materials and Nanotechnology Group, Food Safety and Preservation Department, Institute of Agrochemistry and Food Technology (IATA), Spanish Council for Scientific Research (CSIC), Calle Catedrático Agustín Escardino Benlloch 7, 46980, Paterna, Spain
1.1 Introduction to Polymers in Packaging
According to the Food and Agriculture Organization of the United Nations (FAO), approximately one‐third of all food produced globally is lost or wasted [1]. Food waste is produced throughout the whole food value chain, from the household to manufacturing, distribution, retail, and food service activities. Taking into consideration the limited natural resources available, it is more effective to reduce food waste than to increase food production. For this reason, several efforts have been put for the development of more effective food packaging strategies [2, 3]. Packaging items have become essential to protect food from different environmental conditions. Depending on the type of food, the packaging article can be customized to prevent or inhibit microbial growth, avoid food decomposition by removing the entrance of light, oxygen, and moisture, or even to prevent spoilage from small insects. Additionally, novel packaging items can be monitored to give information about the quality of the packaged food, ultimately diminishing food waste during distribution and transport [4].
Common materials utilized for food packaging include glass, paper, metal, and plastic. The latter are nowadays more frequently used since they have a large availability at a relatively low cost and can display good characteristics for packaging items, such as mechanical strength, barrier properties, and transparency [4, 5]. The most commonly used petrochemical materials for packaging applications can be divided into various families:
Polyolefins and substitutes of olefins, such as
low‐density polyethylene
(
LDPE
) and
linear low‐density polyethylene
(
LLDPE
),
polypropylene
(
PP
),
polystyrene
(
PS
),
oriented polystyrene
(
OPS
),
polyvinyl alcohol
(
PVOH
),
polyvinyl chloride
(
PVC
), and
polyvinylidene chloride
(
PVDC
). Polyolefins are frequently used in reusable bags, paper cups, and stand‐up pouches, while substitutes of olefins such as PVC are popularly used in cling films and in some prepackaged meals.
Copolymers of ethylene, such as
ethylene‐vinyl acetate
(
EVA
) and
ethylene‐vinyl alcohol
(
EVOH
), are typically used to make lid films for trays and barrier interlayers.
Polyesters, such as
polyethylene terephthalate
(
PET
) and other aliphatic and aromatic polyesters, are mainly used to make water bottles.
Polyamide
s (
PA
s) are commonly employed in films or trays for food products that are very sensitive to oxygen.
Most of these materials are made by condensation or addition polymerization of monomers of hydrocarbon or hydrocarbon‐like raw materials, which means that due to their fossil‐based nature and high chemical stability, they are not biodegradable and will accumulate in landfills over the years, causing a negative impact on the environment. Although several recycling strategies are currently being carried out, packaging materials are often contaminated with leftover food, making recycling economically inconvenient and thus unviable. In 2010, primary plastic production was 270 million tons, yet plastic waste was 275 million tons since plastics produced in previous years entered the waste stream, where the sector of packaging was the highest producer of plastics, that is, 146 million in 2015. This has led to an increase in the number of campaigns requesting the removal of single‐use plastics, with the European parliament aiming to ban single‐use plastic cutlery, cotton buds, straws, and stirrers by 2021. Such environmental awareness and implementation of stringent environmental regulations are leading to research for alternatives to food packaging materials and, thus, efforts are being directed, at both academic and industrial levels, at the use of bioplastics in a variety of consumer products.
1.2 Classification of Biopolymers
The above‐described environmental issues, together with the scarcity of oil sources, are the main drivers behind the interest for the development of new materials for food packaging applications. Although bioplastics only account for 1% of the approximately 350 million tons of plastics produced annually, being mostly applied as packaging materials [6, 7], including high‐performance thermoplastic materials and foams, they represent an important part of the Bioeconomy and will undoubtedly shape the future of the plastic industry [8]. As a result, the use of biopolymers in packaging has increased considerably over the past few years due to their sustainable feedstock, biodegradability, and similar processing characteristics as existing thermoplastics [9].
Biopolymers comprise of a whole family of materials with different properties and applications. They include polymers with a “bio‐based” origin and “biodegradable” polymers or polymers featuring both properties. Bio‐based polymers refer to any kind of polymer that is produced from renewable resources, which include both naturally occurring polymers and synthetic polymers produced by means of monomers obtained from biological sources [10]. Naturally occurring polymers are biomacromolecules, that is, molecules of large molecular weights (MW) produced in nature by living organisms and plants. Biodegradable polymers are defined as those polymer materials whose physical and chemical properties undergo deterioration and completely degrade, when exposed to the enzymatic action of microorganisms, to carbon dioxide (aerobic process), methane (anaerobic process), water (aerobic and anaerobic processes), inorganic compounds, and biomass [11]. Bio‐based polymers can be biodegradable but not all biodegradable polymers are bio‐based. Additionally, some synthetic biodegradable polymers could be in a near future partially or fully developed from bio‐based monomers. Bio‐based polymers offer the advantage of conservation of fossil resources by using biomass that regenerates (annually) and the unique potential of carbon neutrality whereas biodegradability is an add‐on property of certain types of polymers that offers additional means of recovery at the end of a product's life [12, 13].
Figure 1.1 Classification of biopolymers widely used in packaging.
Figure 1.1 summarizes the classification of biopolymers grouped according to their origin and biodegradability characteristics. On the top right of the figure, bio‐based and biodegradable polymers are gathered. Nature produces over 170 billion metric tons per year of biomass, yet only 3–4% of this material is being used by humans for food and nonfood purposes [14]. Biomass derived carbohydrates are the most abundant renewable resources available, representing approximately 75% of this biomass, which are currently regarded as the basis for the green chemistry of the future. Most of these biopolymers are mainly made from carbohydrate‐rich plants such as corn or sugarcane, that is, the so‐called food crops, which are also currently referred to as the “first generation feedstock” of bioplastics. This currently represents the most efficient feedstock for the production of bioplastics, as it requires the least amount of land to grow and produce the highest yields. Biomass derived polyesters such as polylactide (PLA) and thermoplastic starch (TPS) are among the most promising biodegradable polymers and they contribute to up to 65% of the family of this type of biopolymers.
The same durability properties that have made traditional petroleum derived plastics ideal for many applications, such as those found in packaging, are leading to terrible waste‐disposal problems as these materials are resistant to microbial degradation and plastics accumulate in the environment. For this reason, some biodegradable polymers, yet based on petrochemical polymers, have been developed in the last few years. The most frequently studied polymers are included in the bottom‐right group, which are aliphatic or aliphatic–aromatic polyesters since neat aromatic polyesters based on terephthalic acid are generally insensitive to hydrolytic degradation and to enzymatic or microbial attack due to their high stability. Indeed, the biodegradation rate increases rapidly when the concentration of terephthalic acid becomes lower than 55 mol%. These petrochemical biodegradable polymers can find several uses in both flexible and rigid packaging applications.
Bio‐based but not biodegradable polymers, which are shown at the top‐left of the figure, currently offer important contributions by reducing the dependence on fossil fuels and through the related positive environmental impact, that is, reduced carbon dioxide emissions. New approaches go toward the complete or partial substitution of conventional plastics by renewable resources such as biomass [15]. Conventional polymers from feedstock routes are being explored for well‐known applications, including the packaging industry [16]. These are generally based on monomers derived from agricultural and food‐based resources such as corn, potatoes, and other carbohydrate feedstock. The new branch of these “green polymers” reflects the “biorefinery” concept [17]. The monomers to produce these bio‐based polymers can be obtained from natural resources, for example catalytic dehydration of bioethanol obtained by microbial fermentation. Although these biopolymers are not biodegradable, they have the same processing and performance as conventional polymers made from natural gas or oil feedstocks. Such developments have recently led to the new paradigm for sustainable food packaging: “Bio‐based but not biodegradable” [18]. This is further evidenced by the recent development of fully bio‐based polyethylene terephthalate (bio‐PET), where the ethylene glycol and the terephthalic acid are both derived from plant‐based sugars and agricultural residues.
The discussion about the use of biomass for industrial purposes is still often linked to the question about whether the conversion of potential food and feed into materials is ethically justifiable. Although the surface required to grow sufficient feedstock for current bioplastics production is only about 0.01% of the global agricultural area of a total of 5 billion hectares (bioplastics), the bioplastics industry is also researching the use of nonfood crops and agricultural residues, the so‐called “second generation feedstock,” with a view to its further use. Innovative technologies are focusing on nonedible by‐products as the source for bioplastics, which includes large amounts of cellulosic by‐products and wastes such as straw, corn stover, or bagasse. This leaves significant potential for using biotechnological processes to create platform chemicals for industrial purposes, among them the production of bioplastics. Therefore, the trend for the development of next generation of bioplastics is currently led by the emergence of conventional polymers made from renewable and nonfood sources.
1.3 Food Packaging Materials Based on Biopolymers
The development of different kinds of packaging materials from biopolymers has seen an increase in the last few years [19]. The use of biopolymers in food packaging can provide physical protection during storage and transportation, and create proper physicochemical conditions for maintaining quality and safety and for extending the shelf life of food [20]. All subsections in Section 1.3 summarize the most important trends in biopolymers for food packaging applications.
1.3.1 Polylactide
The commercialization of PLA began in 1990 though it was known since 1845. PLA is mostly obtained from bacterial fermentation of carbohydrates that can come from renewable resources such as corn or sugar. Fermentation turns the sugar into lactic acid, which is the building block for PLA, but most industrial applications make use of its dimer lactide. NatureWorks LLC (previously Cargill Dow LLC) and, more recently, Corbion (former Purac Bioplastics) are the major suppliers of PLA with a production capacity of over 100 ktons per year, in which this biopolymer is produced in a continuous efficient synthetic process via ring‐opening polymerization (ROP) of the lactide dimer [21]. There are two optical forms: L‐lactide, the natural isomer, and D‐lactide, the synthetic one [22]. The production of the different isomers depends on the microbial strain used during the fermentation process. The polymer crystallinity and the properties of PLA can significantly vary depending on the ratio and stereochemical nature of the monomer [23].
Nowadays, PLA is one of the most researched and commercialized biopolymers and it is seen as a potential substitute for conventional polymers as packaging materials since it is bio‐based and compostable [24]. It has similar properties to traditional polymers such as PET, PS, and polycarbonate (PC) [25]. The most relevant characteristics of this biopolymer are high rigidity, good transparency, heat sealability, printability, and melt processability. Also, it can be processed on large‐scale production lines such as injection molding, blow molding, thermoforming, and extrusion [26]. It is classified as generally recognized as safe (GRAS) by the United States Food and Drug Administration (FDA) and is safe for all food packaging applications [27]. However, it also has limiting properties for its use in packaging applications. For example, its low glass transition temperature (Tg) limits its utilization above 55 °C and it also shows low toughness and ductility [28]. Nevertheless, these narrow circumstances can be improved by varying the ratio of L/D isomers, modifying its stereochemistry, or mixing with other polymers and fillers to improve the mechanical and thermomechanical properties [29].
In the field of food packaging, PLA is ideal for fresh products and those that do not require protection against oxygen, but also it can be used in food trays, bottles, candy wraps, and cups [30]. Accordingly, its high permeation to water makes it suitable for some packaging applications such as extension of the life period of fresh fruit and bread. Some coatings are used as a kind of barrier layer to reduce permeability of this biopolymer [31, 32]. Figure 1.2 shows some commercial packaging articles made of PLA to contain food products.
Figure 1.2 Commercial food packaging articles made of polylactide (PLA): (a) Coffee capsules. (b) Yogurt cups.
Source: Courtesy of Danone (Paris, France).
1.3.2 Polyhydroxyalkanoates
Polyhydroxyalkanoates (PHAs) currently represent one of the most important alternatives to fossil derived polymers in the frame of the Circular Economy [33], showing the highest potential to replace polyolefins in packaging applications due to their biocompatibility and physical properties [34]. PHAs are a family of biopolyesters synthesized by a wide range of microorganisms as carbon storage material. Although they have suitable characteristics such as biodegradability, thermoplasticity, and similar mechanical strength and water resistance to other polymers such as PP and PS [35], their production is expensive due to the high costs of the fermentation and downstream processes. The use of industrial by‐products and waste or mixed microbial cultures (MMCs) represents a viable option to reduce the production costs of PHAs [36].
Among PHAs, the most widely studied and first bacterial member of this family identified was poly(3‐hydroxybutyrate) (PHB). This isotactic homopolyester is biodegradable not only in composting conditions but also in other environments such as marine water and it presents similar thermal and mechanical properties with some petrochemical polymers. However, its use is limited due to its poor impact‐strength resistance and a narrow processing temperature window [37]. To improve these shortcomings, its copolymers such as poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3HB‐co‐4HB)] have been explored. Particularly, PHBV is a good candidate since it has a much lower crystallinity and melting temperature, decreased stiffness and brittleness, and higher ductility. The Tg of these PHA copolymers varies from −40 to 5 °C, and the melting temperature (Tm) also range from 50 to 180 °C, depending on their chemical composition [38].
Figure 1.3 Biodegradable food tray made of poly(3‐hydroxybutyrate) (PHB) obtained by injection molding.
Biomer (Krailling, Germany) and Tianan Biologic Materials (Ningbo, China) are the main producers of microbial PHB and PHBV, respectively. PHAs can be processed by common methods such as extrusion, injection molding, thermoforming, film blowing, and so on [39]. These materials are suitable for very different areas of food and cosmetic packaging, for instance blow‐molded bottles, milk cartons, cosmetic containers, feminine hygiene products, adhesives, paper coatings, waxes, paints, and so on [40]. Figure 1.3 depicts, as an example, a tray made of PHA. Moreover, the use of nanofillers or active substances, such as antimicrobial and/or antioxidant substances, incorporated into a PHA‐based packaging material can change the packed food condition extending the shelf life and improving the protection and/or sensory properties, adding an extra value to the final product [41, 42].
1.3.3 Poly(butylene adipate‐co‐terephthalate)
Poly(butylene adipate‐co‐terephtalate) (PBAT) is a biodegradable aliphatic–aromatic copolymer, synthetized by the reactions of the monomer 1,4‐butanediol, adipic acid, and terephthalic acid. It is biocompatible and biodegradable, being degraded in a few weeks by lipases from Pseudomonas cepacia and Candida cylindracea [43]. Also, it is highly amorphous, it has high ductility and thermomechanical properties comparable with LDPE, and is compostable [44, 45]. Despite these suitable characteristics, PBAT shows a high permeability to water, that is, a poor water barrier property, and fails to achieve the mechanical strength required for some applications [46]. Different approaches have been considered to overcome these disadvantages, such as surface modifications, use of polymer blends, and reinforcement by fillers [47]. For instance, blends of PBAT with PLA can result in a biodegradable article with balanced mechanical properties, though the use of a chain extender or a cross‐linking agent to enhance the interfacial adhesion is usually necessary [48]. Also, the use of nanocomposites based on PBAT and layered silicates have yielded materials with improved mechanical properties [49].
PBAT films can be prepared using cast film extrusion, blown film extrusion, thermo‐compression, and solvent casting methods [50] and they can be used for agriculture, food packaging, waste and compost bags, among others [51]. PBAT is sold commercially by the trade names of Ecoflex® by BASF (Ludwigshafen, Germany), Easter Bio® from Eastman Chemical (Kingsport, USA), and Origo‐Bi® from Novamont (Novara, Italy). It is allowed for food packaging applications by the FDA [52, 53] and the incorporation of antimicrobial substances for active food packaging has recently shown very promising results to enhance food safety [54].
1.3.4 Polybutylene Succinate
Polybutylene succinate (PBS) is a biodegradable and compostable aliphatic polyester produced by polycondensation of succinic acid and 1,4‐butanediol. PBS was exclusively derived from petroleum‐based monomers, but since more recently the monomers can also be obtained by the bacterial fermentation route to produce fully bio‐based polybutylene succinate (bio‐PBS) [29, 55]. So far succinic acid has been mainly produced by electrochemical synthesis due to the high yield, low cost, high purity of the final product, and very low or no waste formation [56]. However, the production of succinic acid by bacterial fermentation uses renewable resources and consumes less energy compared to chemical process. For this reason, companies such as Corbion (Geleen, the Netherlands) and BASF are working on the scaling up of an economically feasible bio‐based succinate production process, despite the fact that these processes have traditionally suffered from poor productivity and high downstream processing costs. Other examples are the development of a biomass‐derived succinic acid production by Mitsubishi Chemical (Tokyo, Japan) in collaboration with Ajinomoto (Tokyo, Japan) to commercialize bio‐PBS or the development of a commercially feasible fermentation process for the production of succinic acid, 1,4‐butanediol, and the subsequent production of PBS by DSM (Heerlen, the Netherlands) and Roquette (Lestrem, France). Myriant (Quincy, USA) and Bioamber (Plymouth, USA) have also developed a fermentation technology to produce the monomers [57, 58]. Thus, in 2015, the annual production capacity of bio‐based succinic acid reached 200 000 tons [59]. In the case of 1,4‐butanediol, conventional production processes use fossil fuel feedstocks, such as acetylene and formaldehyde. Nevertheless, the bio‐based process to obtain the diol involves the use of glucose from renewable resources to produce succinic acid followed by a chemical reduction to produce butanediol [29]. PBS with excellent mechanical properties and processing capabilities can be then produced from the renewable monomers by transesterification, direct polymerization, and condensation polymerization reactions followed by chain extension and lipase‐catalyzed synthesis.
PBS is a semicrystalline aliphatic polyester with a good melt processability and balanced mechanical properties, closely comparable to those of PP. It is tougher than PLA and it shows similar thermal behavior than LDPE and a melting point lower than that of PLA [29, 60]. Its thermal and mechanical properties highly depend on the crystal structure and the degree of crystallinity [61]. The Tg and Tm are approximately −32 and 115 °C, respectively. In terms of mechanical properties, PBS has a good tensile and impact strength with moderate rigidity and hardness [29]. PBS has a wide processing window, which makes the resin suitable for extrusion, injection molding, thermoforming, fiber spinning, and film blowing. PBS has been employed as film, in foaming, and in food packaging containers [60]. However, the relatively poor mechanical flexibility of PBS limits the applications of 100% PBS‐based products. This issue can be overcome by blending PBS with other biopolymers and fillers to improve the mechanical properties to suit the required application and biodegradation rate [62
