The sight of bright, white expanded polystyrene is far less common in today’s food supply chains. But how do this cushioning material and the renewable alternatives score on performance and sustainability? Paul Gander finds out.
If the UK food and drink industry needed a reminder of the pressure it is under to reassess the materials it uses in its packaging, it got it with the confirmation in last month’s Budget that a new tax on plastics containing below 30% recycled material will kick in from April 2022.
Producers offering the most widely-used polymers, notably polyethylene terephthalate (PET), are already commonly bettering the Government’s threshold of 30% post-consumer recyclate (PCR) in bottles and other packaging. Those falling short, or incorporating no PCR at all, will be subject to a tax of £200 per tonne.
Plastics which could struggle to achieve this percentage include expanded polystyrene (EPS), once a popular packaging material, but today, far less so.
Expansion and contraction
There are plenty of reasons why EPS was once ubiquitous, as German-based producer BASF explains. “EPS consists of approximately 98% air, and possesses outstanding insulation and shock-absorbing characteristics,” Klaus Ries, VP business management for styrenics, tells Food and Farming Technology (F&FT). “And don’t forget, it’s still best-in-class in terms of its price/performance ratio.”
Importantly, the hydrophobic properties of EPS are also significant where, for example, product is packed with ice. All these benefits make it a reliable packaging medium for anything from fridges to fresh fish. It still plays an important role in construction, too.
But as packaging, the environmental reputation of EPS has suffered over recent years. It is bulky and highly visible, fragments easily and in many countries and supply chains has not been consistently collected or recycled. While it is sometimes used as transit packaging within a closed loop, it is far less common today in point-of-sale packaging.
Given its high air content, there has even been a spirited attempt by manufacturers to rebrand EPS as ‘Airpop’. But in markets including the UK, this type of gimmick is unlikely to derail what is now a long-term shift to substituting other materials.
MycoComposite – mushroom to measure
One such alternative is Mushroom Packaging or MycoComposite, first developed by US-based Ecovative Design in 2007. This is produced by loading a mould with a substrate combining mushroom mycelium (root mass) with hemp biomass. After six days, the expanded MycoComposite is removed from the mould and dried in a kiln.
“Mushroom Packaging is cost-competitive with incumbent foam products, including fabricated polyethylene and ethylene vinyl acetate,” Ecovative co-founder and director of business development Gavin McIntyre tells F&FT. He includes EPS in this ‘cost-competitive’ category, but only in volumes under 500,000 units a year.
McIntyre claims that resin prices for EPS are “comparable to our full stack of ingredients”. “We also have methods of reducing our cost further, which is challenging for a plastics foam,” he adds.
Meanwhile, with the upstate New York business now focusing many of its efforts on the potentially high-margin meat-substitute market, it has licensed production of Mushroom Packaging to a number of manufacturing partners in the US and beyond.
One of these licensees, the UK-based Magical Mushroom Company, has just officially opened, adding to its initial 5,000-square-foot operation with a new 30,000-square-foot site.
Paul Gilligan is chief operating officer of the UK company, which is owned by Symbiotec. His business has already produced cushioning for products in glass bottles and jars, and he says fish boxes are another option for the future. His immediate focus is on non-food sectors.
“Mushroom Packaging is not certified for direct food contact,” cautions McIntyre at Ecovative, adding that there is no reason why other companies could not seek that approval.
Biodegradability is a key advantage, says Gilligan. “It will biodegrade in 45 days, even if you put it in soil,” he explains.
When ‘wool rhymes with ‘cool
Another renewable and biodegradable material now being used more widely for insulation in food supply chains is sheep’s wool. Established just over a decade ago, UK company Woolcool supplies pouch-style film inserts filled with wool for food and pharmaceutical customers.
“The product can certainly be reused,” MD Josie Morris tells F&FT, pointing out that a return-and-reuse model is utilised by many (but not all) online delivery companies, such as fresh produce supplier Abel & Cole.
Where this is not the case, inserts can be collected and returned to Woolcool. “But if people don’t want to send them back, the wool is 100% compostable,” says Morris, adding that the company puts no additives with the natural fibres.
“This ‘technology’ borrowed from the sheep often allows us to reduce the weight and size of the box,” she says. “Combining this with ice packs has allowed a lot of our customers to eliminate the use of temperature-controlled vehicles.”
Not all Woolcool’s customers use a home-delivery model. “We work with a few wholesale meat and fish companies which deliver direct to restaurants or retailers,” says Morris.
Formats can be tailored to specific needs. For example, she says, in an exclusive system being developed for one customer, the wool is being made more rigid than is normally the case – giving it a cushioning as well as an insulating role.
Corrugated and pulp
Fibre of a different kind is processed at Glasgow-based Cullen, which produces both corrugated board protective packaging and moulded pulp.
“EPS is excellent as cushioning,” company spokesman Mike Pelosi admits. “But not so good for the environment. In a cushioning role, moulded pulp is an incredibly protective material, and you can build in extra protection where required.”
Similarly, corrugated can provide temperature control for fresh products. “We worked with leading UK retailer Waitrose to ensure that their supplier can ship fresh fish to them in a double-walled corrugated box packed with ice,” says Pelosi. A coating applied to the board provides a moisture barrier, but does not interfere with recyclability, the company claims.
The two fibre-based materials can be combined in packages for shipping and e-commerce. For home-delivery wine in glass bottles, Cullen’s Clinker product twins three moulded pulp inserts with a corrugated box. Ridges can be built into the mould to provide extra crush protection, Pelosi points out.
Another retailer is using ovenable pulp trays from Cullen for muffins, baked, delivered and – if required – displayed in the same tray. Other types of tray are popular for fruit, for example. “Moulded pulp can compete very well on price, but it does depend on order quantities,” he says.
Behind the scenes, EPS, too, is fighting back to reassert its green credentials. BASF quotes a study by Conversio which puts Europe-wide recycling of EPS packaging waste at 33% in 2017, while in Germany the figure is said to be 42% (2018).
Supply chains which use large volumes of EPS, such as fresh fish, will often have their own collection and recycling networks – as is the case with Billingsgate Fish Market in London, for example.
But while BASF calls mechanical recycling of EPS in Europe “state-of-the-art”, this is not a closed-loop system. Instead, even where EPS can be segregated from other plastics, the recyclate tends to be used in areas such as insulation for the construction industry.
Currently, BASF is putting significant resources into developing its own ‘chemical recycling’ technology. This uses pyrolysis and purification to break mixed plastics down into their component chemicals. These can then be recombined to produce different ‘virgin’-quality polymers.
The challenges in reaching the UK Government’s 30% PCR target remain, though. For now, chemically-recycled plastics do not come under the official definition of ‘recycled’ content. As for mechanically-recycled EPS, well, that does not find its way back into packaging at all, and certainly not food-grade packaging.