Plastic films are used for packaging a wide range of products, offering protection against humidity and potential contaminants. Over time, however, these films let in air, diminishing the properties of the packed products. And while multilayer films combining several plastics are often used to improve protection, most of this packaging cannot be recycled. The researchers behind the EU-funded WHEYLAYER project found a cheese-based biodegradable alternative to conventional multilayer films.

The project team developed a novel packaging material based on whey, a liquid by-product obtained from the production of cheese. The whey is used as a bio-coating – a biodegradable film - for the plastic, offering additional protection while also being recyclable. Tests ran on the Oxygen Transmission Rate (OTR) of the packaging showed that a layer of whey improved the protection level 30-fold compared to conventional plastic films.

What makes whey such an interesting material for packaging is that it contains 6.5 grams of 'protein' per liter. “Protein molecules are very long and during the drying process they form a structural barrier that is impermeable to oxygen,” says Elodie Bugnicourt, Ecomaterials group leader at IRIS, the research company that coordinated the WHEYLAYER project from Barcelona, Spain.

In packaging applications, the whey product is placed between two layers of plastic – either synthetic or bio-based - thus preserving the flexibility and mechanical strength of the packaging material. As it is much less permeable to oxygen, the whey product provides additional protection against humidity and oxidation, the chemical reaction resulting from the interaction between the wrapped product and air that effectively speeds up ripening and rot.

Europe produces more than 45 million tonnes of whey every year, but 45 percent of it is discarded. Additionally, the plastic based on whey is easily recyclable because the whey product can be “washed” off from the plastic layers by treating it with special enzymes ('protease' and 'alcalase'), the biological catalysts that help it decompose.

For Europe’s packaging industry, such a recyclable product is important because they have to comply with waste legislation. “Many packaging companies are trying to turn to greener solutions, which makes this product attractive,” says Bugnicourt. Also, the reuse of an existing waste product lowers the carbon footprint, she adds.

“We have finished the research and development, and now we have to get the technology successfully onto the market,” says Bugnicourt, who adds that the project consortium has now patented the technology. “There is an early-stage business strategy, and it addresses plans for different sectors and different applications,” she explains. She expects that some of the flexible packaging products could reach the market in the coming years.

The WHEYLAYER project team included 14 industrial and academic partners from Spain, Hungary, Slovenia, Italy, Germany and Ireland, and was coordinated by PIMEC, the SME association of Catalonia that represents over a 100,000 Spanish companies. The project ran from November 2008 to October 2011 and received an EU grant of €2.8 million.

WHEYLAYER 2, a follow-up project, started in August 2012 within the Demonstration Activity programme. WHEYLAYER 2, also funded by the EU, will focus on up-scaling the results obtained in the WHEYLAYER project, to prove their industrialisation potential and lead to their commercialisation. It will target not only packaging producer and food packer SMEs, but also other, larger businesses seeking more sustainable wrapping methods, including pharmaceutical and cosmetic companies.