Many packaged foods, such as dairy products, bakery goods, coffee, snacks and juice, need to be protected from contact with air to maintain freshness and quality. The sealing layer in laminated packaging is usually made from plastic or aluminium foil, materials that serve their purpose well but do not readily break down after disposal. Also, plastics are manufactured from increasingly expensive, non-renewable petroleum.
A research project at the Institute for Polymer Technology at Chalmers University of Technology in Gothenburg, Sweden, found that the naturally occurring polysaccharide carbohydrate xylan provides an excellent oxygen barrier, and that it can be applied as a thin film on a variety of materials, including paper and cardboard.
In response to consumer and regulatory demands for waste reduction—and to rising raw material prices—the packaging industry is keenly interested in alternatives. Xylophane AB believes it can carve out a profitable niche with its eponymous barrier product.
An unexploited resource
Xylans are among the most common carbohydrates found in the plant world, but until now they have had virtually no industrial applications. A generic name used to describe a wide variety of highly complex polysaccharides, xylans are almost as ubiquitous as cellulose in plant-cell walls
Xylophane bioplastic is made from agricultural residual products such as bran and seed shells from grains. The product provides a barrier not only against oxygen but also protects against fats and smells, making it especially interesting for storage of spices, coffee and tea.
One of the attractive characteristics of Xylophane is that it can be manufactured in a very thin film, which can be applied as a protective layer on the inside of paper or cardboard packaging. And because Xylophane is water-soluble, it can be fixed to the substrate material without using organic solvents. In a process known as dispersion coating, powdered Xylophane is is dissolved in water and distributed on the substrate with rollers, rods or blades. The layer is then dried with heated air or infrared light.
Demand for environmentally adapted packaging
Most stakeholders in the packaging industry are well aware that reduced environmental impact is a high priority. But replacing traditional practices is both complicated and costly. For example, juice packages can include a plastic liquid barrier, cardboard, plastic glue, an oxygen barrier, another glue layer and another liquid barrier—a total of six layers.
Any new packaging that hopes to compete must be reasonably priced, and preferably will not require any changes to the packaging process. At the same time, it has to be able to withstand transportation and storage, and it must not leave any chemical residue on the contents.
Xylophane AB is cooperating with several partner companies to develop and adapt its barrier material for various applications. Xylophane is currently produced only on a small scale for customer testing, and an important next step will be to scale the process for mass production.
Research on bioplastics
Xylophane AB is not alone in the pursuit of commercially viable bioplastics; indeed, laboratories around the world are conducting research on environmentally adapted packaging materials. The main obstacles are generally higher prices than conventional materials and problems meeting technical requirements. For the time being, the bioplastic with the most success in large-scale production is polylactic acid, or PLA, which is based on starches derived from corn and sugar cane.
Article published in June 2009