H2020 REFUCOAT Project: Fully recyclable food packaging with improved gas barrier properties and new functionalities through the use of high-performance coatings

Multi-layer polymer food packaging is the industry standard, enabling multiple necessary functionalities not present in any single layer. However, the multiple bonded layers that act as a barrier against oxygen and moisture are difficult to recycle, and synthetic plastics are not biodegradable, creating a growing problem at end-of-life. Environmental concerns are shared by governments, industries, and consumers, but finding recyclable and/or biodegradable single-layer alternatives that perform as well as conventional packaging has been a challenge.

With funding from the Bio-based Industries Joint Undertaking (Opens in new window), a public-private partnership between the EU and industry, the ambitious REFUCOAT (Opens in new window) brought together 12 multidisciplinary partners along the entire value chain from 5 EU countries to tackle the problem. REFUCOAT advanced the potential of two promising biodegradable biopolymers and also pushed the boundaries of what might be possible, demonstrating the use of bacteria-eating organisms (bacteriophages) in active coatings. Bringing biopackaging to life by harnessing microbes and natural metabolites Many microorganisms are miniature production lines for polyhydroxyalkanoates (PHAs), fully biodegradable bioplastics with tunable properties.

The subject of intensive research, high-molecular-weight PHAs suitable for industrial food packaging applications have until now remained elusive. REFUCOAT successfully harnessed microorganisms to valorize agri-food waste, resulting in biodegradable PHA-based coatings for food packaging. Polyglycolic acid (PGA) is another biodegradable polymer, and its degradation product (and building block or monomer), glycolic acid, is a naturally occurring metabolite. Commonly used as a suture material, its high mechanical strength and excellent gas barrier properties also make PGA attractive for food packaging applications. According to Javier Marzo Muñoz, project manager at AIMPLAS(Opens in a new window) and coordinator of REFUCOAT, and Lorena Rodríguez, head of the packaging department at AIMPLAS and principal investigator of REFUCOAT: "Currently, glycolic acid is produced either by the carbonylation of formaldehyde or by the alkaline hydrolysis of chloroacetic acid using toxic or harmful substrates and/or adverse reaction conditions.

At REFUCOAT, we developed a gold-based catalytic process to convert monoethylene glycol into PGA for greener production of this biodegradable biopolymer. Finally, the team harnessed the bacteria's natural viral enemies to form innovative active barriers that extend product shelf life. Preliminary data demonstrated encouraging inhibition of Salmonella growth with bacteriophages. Further research will support approval by the European Food Safety Authority (Opens in new window). Supporting a sustainable medium-term.

For over half a century, multilayer packaging, including non-renewable resources like aluminum, has prevented perishable products from rapidly perishing. However, it is difficult and expensive to recycle, creating a significant environmental and economic burden. The diverse expertise of the REFUCOAT consortium was uniquely positioned for extensive research into the development of fully recyclable, bio-based, single-layer food packaging. "REFUCOAT developed promising, fully biodegradable bioPGA and PHA polymers for food packaging. Furthermore, the use of bacteriophages as active coatings for food packaging demonstrated clear potential.

In the context of these activities, our partners have achieved intermediate and more sustainable packaging solutions," summarizes Marzo Muñoz. As the team continues to search for bio-based monolayer packaging that meets market requirements, the scientists hope that policies will encourage the greening of the current plastics value chain. REFUCOAT has prepared a Policy Brief (Opens in a new window) with specific recommendations to support this through greater sustainability, improved recycling processes, and increased investment in biomass and bio-based industries.