No more PET peeves?
Recycled polyethylene terephthalate (rPET) is a sustainable packaging alternative to support the circular economy using recycled materials and minimising waste. The team behind the Leaf No Waste project at Teagasc Ashtown is currently investigating and trialling the use of novel rPET for fresh produce packaging using an automatic thermoformer and tray sealer.
Tigist T Shonte demonstrates the rPET packaging system at Teagasc Food Research Centre.
The choice of packaging material plays an important role in maintaining quality, extending shelf life and ensuring consumer health and safety of fresh produce. Polyethylene terephthalate (PET) as a packaging material has consistently increased worldwide due to its excellent transparency, light weight, gas and water barrier properties, impact strength, and UV resistance. PET can be made from both fossil- and bio-based sources.
The heat-sealable properties of PET also facilitate technological advances for use in barrier solutions, hot-fill and thermoforming applications in a wide range of foods.
The global PET packaging market is projected to grow from $39.23 billion (€35.5 billion) in 2022 to $55.46 billion (€50.25 billion) by 2029, at a combined annual growth rate of 5.1% in the forecast period 2022- 2029. Bottled water and carbonated soft drinks are the dominant markets for PET packaging.
Aiming for increased circularity
PET plastics are widely produced and used, and more than half of them are disposed of without being recycled. Global and EU waste management rates showed that, in 2016, only 16% of polymers in flow were collected for recycling while 40% were sent to landfill and 25% were incinerated.
European countries have increased efforts to improve recycling rates. To meet EU Packaging Regulations (SI 322/2020), Ireland must now hit recycling targets of 65% of all packaging by 2025 and 70% by 2030.
Up to 80% of rPET food trays contain raw materials of recycled PET, reducing the polymer, oil raw material and energy used to manufacture a virgin PET tray, thereby promoting a circular economy and minimising plastic waste. Due to reduced material usage and high recycled content, the carbon footprint of rPET tray offerings are in excess of 85% lower than virgin mono PP food trays.
Virgin PET plastics can only be recycled for a limited number of times before becoming too degraded to be used again. This is because of a sharp reduction in the properties of the material due to deterioration of the thermooxidative and thermo-mechanical degradation of the chains, as well as hydrolytic scission.
A fresh approach to fresh produce
rPET and PET mono film have a number of key features that make them suitable for fresh produce packaging. They are lightweight with a high level of rigidity and an excellent barrier performance, suitable for Modified Atmosphere Packaging (MAP) to extend shelf life, and offer glass-like clarity for clear presentation of products ideally suited to fresh produce packaging (e.g. fruits and vegetables, poultry). Mono PET film is designed with 30% post-consumer recyclable materials, which greatly reduces carbon footprint as it produces the lowest greenhouse gas emissions, water usage and total energy usage of all plastics in manufacturing (including bio-based plastics).
PET film is a strong, shred-resistant and lighter film with a thickness starting from 20 microns. PET film is a coextruded polyester film with a layer of amorphous heat-sealable polyester film on one surface and plain polyester on the other, ideal for chilled applications where strong, permanent seals with good ‘seal-through contamination’ properties are required. It can be heatsealed to itself or to rPET trays.
The Leaf No Waste project packaging team at Teagasc Ashtown is currently investigating and trialling the use of PET for fresh produce packaging using an automatic thermoformer packaging system based in the National Prepared Consumer Food Centre. The lightweight novel rPET plastic punnets are fully recyclable compared to PP (polypropylene), which is the most used material in Irish packaging. The use of thermoformed packaging materials can cut down on the warehousing cost of the trays currently used by the industry. PET monomaterials, if successfully used, can eliminate the use of Poly Vinyl Chloride (PVC) in fresh produce packaging.
The team is also assessing how these novel packaging formats impact product shelf life, while also looking at potential reductions in plastic use for packaged products and the overall cost implications of transitioning to these packaging formats.
Ireland must recycle 70% of all packaging by 2030 to meet EU Packaging Regulations.
ACKNOWLEDGEMENTS
With thanks to the Science Foundation Ireland Food Waste Challenge for funding and to National Prepared Consumer Food Centre, Teagasc Food Research Centre, Ashtown for hosting.
CONTRIBUTORS
Tigist T. Shonte, Postdoctoral Researcher, Leaf No Waste project, Teagasc Food Research Centre, Ashtown, Dublin.
Shivani Pathania, Research Officer Food Industry Development Department, Teagasc Food Research Centre, Ashtown, Dublin.
Photography by: John McElroy.