Héctor Rivero and Jezabel Santomé, packaging researchers at AIMPLAS
In recent years, the food packaging sector has undergone major changes thanks to the promotion of new strategies that have swapped the current waste management model for a circular model. This change has been followed by most governments worldwide. For example, the European Parliament approved the Circular Economy Action Plan in February 2021 to move towards a carbon-neutral, environmentally sustainable, toxic-free and fully circular economy by 2050.
In line with this circular economy model, the EU has set an objective to reduce plastic waste. Given that approximately 40% of the world’s plastic is used in packaging production, the packaging sector has naturally been involved in the changes introduced by sustainable new growth strategies. The target set by the EU stipulates that all packaging must be recyclable by 2030 and that the use of reusable packaging must increase. Moreover, a European law has been approved to ban the use of single-use packaging. The list of affected products is included in the SUP Directive and its transposition into Spanish draft of the Law on Waste and Contaminated Soils, which refers to food and drink packaging and also establishes a tax on non-reusable plastic packaging.
While it is important to promote measures to reduce plastic consumption, it is also necessary to highlight the fundamental role played by plastic packaging in society. Plastic allows us to tackle food waste and ensure food safety. It is essential for preserving food and protecting it from a number of deterioration factors, such as oxygen and water vapour. These factors cause food to lose its organoleptic properties and reduce its shelf life. In addition, plastic packaging is subject to the most stringent national and international legislation and controls, which makes it the most regulated and, therefore, the safest material for food contact and consumption. However, most food packaging is made of different polymeric materials that form multi-layered structures. This gives the material high barrier properties and extends the product’s shelf life. However, the end-of-life management of plastic products can sometimes present a challenge. Product recyclability is made more complex by the different types of materials used to manufacture materials.
EU strategy encourages the use of recyclable, reusable and compostable packaging and, to that end, different packaging types that have good barrier properties and are in line with circular economy strategies are being developed. Such packaging types include recyclable single-material packaging, multi-layered recyclable packaging and compostable packaging.
Today, there are solutions for the different packaging types on the market. However, until now, in some cases packaging product has not presented all the characteristics required by certain foods. One of the main shortcomings of new packaging materials is that they do not have the required oxygen barrier properties; more importantly, they do not have barriers against water vapour. As a result, extensive work is being carried out to create a food packaging solution that has high barrier properties but does not compromise on compostability or recyclability. In all of these packaging alternatives, whether recyclable or compostable, three strategies are possible: synthesis of new polymers with improved barrier properties, physical modification of polymers by adding fillers or polymeric coatings with high barriers to gas.
The use of bioplastics in the development of new packaging is a rising trend that uses polymers such as polyethylene furanoate or PEF. PEF is made from renewable raw materials and has good barrier and thermal properties. According to their chemical structure and properties, this biobased polymer is currently being presented as a future alternative to PET. Another option is polyhydroxyalkanoates or PHAs. These polyesters are biosynthesised by bacterial fermentation. Within the packaging sector, they are notable for their good barrier properties compared to other biodegradable polyesters, in addition to their high biodegradation capacity in different environments, including in soil and aquatic environments. Moreover, fillers can be incorporated into the polymeric substrate to strengthen the barrier properties of plastic materials. This methodology can be carried out during either the melt extrusion process or synthesis of the base polymer itself. According to this, different studies with cellulose nanoparticles and clay have revealed improved polymeric barrier properties when this strategy has been used. The results differed depending on the size and geometry of the particles incorporated.
Barrier coatings have become an increasingly popular alternative in the packaging industry. Extensive work is being carried out to obtain barrier solutions based on coatings that offer good barrier properties with very thin layers. Coating application technologies are well known in the packaging sector, as most coatings have been formulated for conventional printing technologies like flexographic and rotogravure printing. Moreover, since only very thin layers of these coatings are applied, the coating forms only a small part of the actual structure and does not affect the material’s compostability or recyclability. In some cases, coatings can even contribute to recyclability; for example, PVOH (polyvinyl alcohol) is a polymer with excellent oxygen barrier properties, as well as mechanical and film-forming properties. It is water soluble, so the PVOH is removed in the recycling plant when the material is submerged in hot water and stirred during the first wash. When the PVOH is washed off with water, the material becomes recyclable.
Another coating or surface treatment that is considered a viable solution for new compostable polymers, which have poor gas barrier properties, are metallic or metal-based coatings such as aluminium and silicon oxides. Currently, many of the companies that work with compostable plastics are working in this area to improve their properties.
AIMPLAS, the Plastics Technology Centre aims to offer businesses alternatives to current solutions on the market by working on numerous projects to develop recyclable or compostable packaging solutions with high water vapour and oxygen barrier properties. An example of such a project is ENVASE 4.0 (PACKAGING 4.0),financed by the Valencian Institute for Business Competitiveness (IVACE). The ENVASE 4.0 project aims to develop barrier packaging for food products by using bioplastics and recyclable, multi-layered structures, as well as active antimicrobial and antioxidant ingredients to extend the shelf life of products and promote sustainability. Furthermore, the GUACAPACK project, financed by the Valencian Innovation Agency, aims to develop an innovative biodegradable packaging system based on PLA. The project uses a starch-based coating extracted from avocado waste to provide oxygen barrier properties. Antioxidants are also extracted from the avocado waste that are then used.
In this project, AIMPLAS has carried out a life-cycle assessment (LCA) to evaluate the environmental impact of the new packaging compared to conventional packaging. AIMPLAS can also evaluate the compostability of the packaging at the end of its useful life, as AIMPLAS has TÜV Austria-approved laboratories that can award products with the compostability ecolabels “OK compost INDUSTRIAL” and “OK compost HOME”. Moreover, AIMPLAS has also been recognised by RecyClass as a certification body authorised to carry out audits and verify the recyclability of packaging.