From milk cartons and soup packets to fast-food burger boxes, coated paper and cardboard is one of the most widely used materials for food and beverage containers in the world today. Around seven million tonnes of it is manufactured globally each year, much of it ending up in landfills after use. While the paper and cardboard layers degrade rapidly, the petrochemical-based polyethylene coatings, which account for around 20% of the packaging weight, take decades to break down.
European researchers have developed an innovative solution that not only ensures the packaging is easily recyclable and biodegradable, but can also be produced in a sustainable way. Working in the EU-funded BIO-BOARD project, they have developed biomaterials to replace polyethylene coatings made from little-used or unused by-products of the food processing industry, such as whey from cheese-making and potato juice from starch production.
“BIO-BOARD responds to increasing demand from food packaging producers for biomaterials that can substitute synthetic coatings without compromising packaging properties for liquid and dry goods,” explains Elodie Bugnicourt, the project coordinator at IRIS in Spain. “Using extracts from whey and potato fruit juice we have developed materials that meet those requirements and evaluated their use in coated packaging production processes.”
The raw materials for producing the protein-based coatings are abundant. Of the 50 million tonnes of whey produced annually in Europe, up to 50% is currently discarded, along with 65 000 tonnes of dried fruit juice protein and 140 000 tonnes of dried potato pulp. The difficulty is turning those plentiful and sustainable resources into a usable biomaterial that can match the physical properties of fossil fuel-based plastics.
The BIO-BOARD researchers tested different compositions and selected the most promising to make bio-based coatings, evaluating the materials in terms of barrier properties, adhesion, flexibility and their suitability to store solid and liquid food. In a pilot production run, they tested different extrusion techniques to apply the coatings to paper and cardboard, and also investigated other potential packaging production processes, such as injection coating and multi-layering the materials. The goal was to develop a way to apply the coatings in an efficient and cost-effective manner.
“We have made enormous progress since BIO-BOARD began but several key challenges remain, including reducing the thickness and increasing the processability of the biomaterial coatings to meet modern packaging requirements, and developing production processes that are as quick and cost-effective as using synthetic materials,” Bugnicourt says.
Several of the project partners already have experience of addressing similar challenges, having contributed to the highly successful Wheylayer project that developed whey protein-coated plastic films to replace expensive polymers in food packaging and improve recyclability. Also funded by the EU, Wheylayer is on its way to commercial implementation, and served as an inspiration for BIO-BOARD.
Though further research will be required to bring biomaterial-coated paper and cardboard food packaging into commercial production, the market for such a product is potentially huge. It could also have applications in other industries with some adaptation, Bugnicourt notes. Even with current technological limitations, the global bioplastics market is growing at 20 to 30% per year, driven by consumer demand for environmentally friendly products and the volatile price of fossil fuels.
For packaging producers and the agro-food industry, a sustainable alternative to petrochemical-based packaging should, in the long term, lower costs and increase competitiveness, while helping to reduce waste and protect the environment for the benefit of all. The project is due to end in October 2015.