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This article appeared in the June 2024 issue of Resource Recycling. Subscribe now to access all print content.
In late 2023, the US Food and Drug Administration issued “no objection letters” to 14 companies in North America, Asia and Europe to use recycled resin products in food contact packaging. However, to date, there has been no information or promotion on the applications of food-grade recycled polypropylene resins used in food contact packaging.
One of the main reasons for this is that PP is at the beginning of its recycling journey. If you think about the most widely recycled polymers to date, PET and HDPE, their recycling journeys didn’t happen overnight either. I remember when we were first producing food-grade RPET in the UK, there was quite some resistance to using it in food contact packaging and it required extensive testing before it was adopted into standard production. Now this is commonplace.
PP is currently going through the exact same phase.
The slow recycling journey of PP
However, PP accounts for more than 20% of global plastics production, with food packaging being one of its major products: in fact, around 75% of PP rigid packaging in the EU is for food contact, which represents around 10% of total PP demand.
One of the main reasons why recycled food-grade PP resin, even with LNO, is not yet being used in food packaging has to do with hesitation about the safety of this new resin. The hesitation stems from a lack of experience that this food-grade recycled material is safe for use in consumer food contact packaging.
The challenge with RPP is that, until now, it has not been possible to accurately distinguish between PP packaging that has contained non-food products and PP packaging that has contained food. As a result, food-grade recycled PP is currently limited to advanced recycling technology processes based on closed-loop recycling, manual sorting, or mass balance, which are not yet recognized as recycling in the European Union.
Characterization of residual contamination levels of rPP
But progress is coming fast, thanks to NextLooPP’s ongoing science-driven research into creating a circular society for post-consumer food-grade PP.
Achieving this required addressing all the obstacles along the way and thoroughly considering the specific sorting and decontamination requirements of the PP recycling process.
This prompted NextLooPP to conduct a science-based study to determine residual contamination levels in previously uncharacterized post-consumer PP packaging.
Due to a lack of data showing misuse/misselection rates within PP feedstocks, there was no reliable way to define the residue levels that could migrate into food, nor was it possible to know which molecules should be targeted in the decontamination process.
The aim of the NextLooPP study was to identify substances in RPP samples that may have deviated from the expected input stream and pose a problem for the final safety of recycled plastics. A key question was to determine whether the observed substances had the potential to be genotoxic.
This is an important criterion for food safety assessment, since these substances may result from incorrect selection of non-food PP packaging items, not necessarily misuse.
It’s all in the package
Consumer PP packaging is olefin-based, making it less susceptible to consumer misuse. Most PET packaging is tightly sealed and relatively durable, making it an excellent choice for containers when used to store hazardous materials. Similarly, HDPE packaging can also be used in this application, as it is bottle-shaped and airtight. PP food containers, on the other hand, are less likely to be bottle-shaped, and are far more likely to be pots, tubs or trays with limited airtightness, making them less susceptible to consumer misuse.
Characterisation of residues in used packaging, categorised into monopolymer fractions, was undertaken by analysing and testing multiple batches of food and non-food samples to see what molecules were present and if there were any areas of concern.
To achieve this, our team of scientists worked on a batch of 20 tonnes of PP bales sourced from a UK-based materials recovery facility. They used an automated optical sorter to separate the natural, white and coloured colour fractions, then manually sorted each colour fraction into food and non-food products.
The analytical study included 700 tests, representing approximately 17,500 different PP packs, based on 25 significant size flakes per test, which was estimated to represent a 7% cross-section of packs from a batch combination of 260,000 packs.
Following this contamination study, NextLooPP characterized the contamination levels in PP and concluded that they were approximately 10 times lower than would be expected in HDPE milk bottles and 100 times lower than would be expected in PET, which is not surprising given the application that makes PP the packaging material of choice.
Reliability of food-grade rPP resin
Understanding the sorting and decontamination requirements needed to enhance the recycling process will further enhance the effectiveness of NextLooPP, Nextek’s global, multi-participant project soon to launch in the Americas.
This data is essential for recycling food-grade PP packaging into high-value recyclables that can be safely used in new food contact packaging, and we believe the performance standards we have developed will enable organizations to achieve high levels of technical performance and commercial and legal confidence for the food-grade RPP that can be included in food contact packaging.
Leveraging NextLooPP’s expertise and technical backing, the company aims to license NextLooPP technology and enable rapid adoption of resin standards into RPP food-grade packaging produced in the United States.
Finding an effective local solution to the end of life of used food-grade PP packaging is the driving force behind NextLooPP’s 53 participants, who are actively producing and testing a variety of unique grades of high-quality food-grade recycled PP resins produced using Nextek’s patented PPristine decontamination technology.
Proven in commercial testing
Eighteen of NextLooPP’s brand and converter participants have completed 55 commercialization trials using five PPristine resin grades: natural food grade IM, natural food grade, white food grade, mixed color food grade, and non-food grade mixed color INRT, and the results have been impressive. For example, trials using 30% of NextLooPP’s PPristine resin in both extrusion and thermoformed trays achieved product quality comparable to virgin products without changing processing conditions.
Sort Conversion
While the multi-participant project is currently fine-tuning the resin quality criteria that will become standard for food-grade recycled PP, recent trials conducted by NextLooPP in collaboration with Tomra have identified major advances in the automated sorting of food-grade PP packaging.
These sorting trials, carried out in February, combined TOMRA’s near-infrared visual spectroscopy with the company’s latest deep learning technology, GAINnext, to achieve food-grade purity levels of over 95% for packaging applications.
This groundbreaking development is a huge boost for the NextLooPP project: GAINnext can potentially be deployed in all PP packaging sorting facilities, helping to generate valuable food-grade PP PCR streams.
By providing sorted food-grade PP PCR streams, GAINnext will enable even more recycling operations around the world to run the NextLooPP decontamination process.
The finish line is near
After nearly four years of intensive collaboration, NextLooPP participants have now broken the final barrier to producing food-grade recycled PP from post-consumer packaging to manufacture new circular economy products, and the NextLooPP team looks forward to launching the NextLooPP Americas project to achieve similarly impressive results.
Increasing production of recycled food-grade PP resin is a major step towards stimulating growth in this sector and creating a market where sustainable solutions can compete with and replace virgin polymers.
Edward Kosior has worked in the plastics recycling sector for 48 years, 22 as an academic and 26 in recycling and sustainable solutions. He is the founder of consulting organization Nextek Ltd., NextLooPP, a global initiative working on circular recycling of post-consumer polypropylene, and COtooCLEAN, which uses proprietary supercritical CO2 technology to decontaminate, deink and strip soft plastic films to meet food-grade standards.
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