Experiments on the degradation of different plastic materials. Top left is a common LDPE plastic film. Top center and right are the researchers' amylose-based bioplastic and a plastic made from corn starch, respectively. At the bottom are three different bags made from conventional bioplastics. A) shows the start of the experiment. B) shows the degradation after 8 days, C) the degradation after 11 days, D) 21 days E) 41 days and F) shows the degradation after 54 days. (Courtesy of Camilla Skovbjerg)
Researchers invent 100% biodegradable 'barley plastic' suitable for food packaging
Enormous islands of plastic float in our oceans and microscopic particles of it are in our bodies. The durability, malleability and low cost of plastics has made them ubiquitous, from packaging to clothing to aircraft parts. But plastics have a downside. Plastics contaminate nature and can be difficult to recycle.
Now, researchers at the University of Copenhagen’s Department of Plant and Environmental Sciences have invented a new material made from modified starch that can completely decompose in nature – and do so within only two months. The material is made using natural plant material from crops and could be used for food packaging, among many other things.
"We have an enormous problem with our plastic waste that recycling seems incapable of solving. Therefore, we’ve developed a new type of bioplastic that is stronger and can better withstand water than current bioplastics. At the same time, our material is one hundred percent biodegradable and can be converted into compost by microorganisms if it ends up somewhere other than a bin," says Professor Andreas Blennow of the Department of Plant and Environmental Sciences.
Only about nine percent of plastic is recycled globally, with the rest being either incinerated or winding up in nature or dumped into enormous plastic landfills.
Bioplastics already exist, but the name is misleading, Blennow says. While today’s bioplastics are made of bio-derived materials, only a limited part of them is actually degradable, and often only under special conditions in industrial composting plants.
"I don't find the name suitable because the most common types of bioplastics don't break down that easily if tossed into nature. The process can take many years, and some of it continues to pollute as microplastic. Specialized facilities are needed to break down bioplastics. And even then, a very limited part of them can be recycled, with the rest ending up as waste," says the researcher.
Starch from barley and sugar industry waste
The new material is a so-called biocomposite and composed of several different substances that decompose naturally. Its main ingredients, amylose and cellulose, are common across the plant kingdom. Amylose is extracted from many crops, including corn, potatoes, wheat and barley.
Together with researchers from Aarhus University, the research team founded a spinoff company in which they developed a barley variety that produces pure amylose in its kernels. This new variety is important because pure amylose is far less likely to turn into a paste when it interacts with water compared to regular starch.
Cellulose is a carbohydrate found in all plants. The cellulose used by the researchers is a so-called nanocellulose made from local sugar industry waste. These nanocellulose fibers, which are one thousand times smaller than the fibers of linen and cotton, are what contribute to the material’s mechanical strength.
The new biomaterial is produced by either dissolving the raw materials in water and mixing them together or by heating them under pressure. By doing so, small 'pellets' or chips are created that can then be processed and compressed into a desired form.
So far, the researchers have only produced prototypes in the laboratory. But according to Professor Blennow, getting production started in Denmark and many other places in the world would be relatively easy.
"The entire production chain of amylose-rich starch already exists. Indeed, millions of tons of pure potato and corn starch are produced every year and used by the food industry and elsewhere. Therefore, easy access to the majority of our ingredients is guaranteed for the large-scale production of this material," he says.
Prototypes for food packaging
Blennow and his fellow researchers are now processing a patent application that, once it has been approved, could pave the way for production of the new biocomposite material.
The researcher is already collaborating with two Danish packaging companies to develop prototypes for food packaging, among other things. Though it is difficult to say when this biofriendly barley-based plastic will reach the shelves, the researcher predicts that the new material may become a reality in the foreseeable future.
“It's quite close to the point where we can really start producing prototypes in collaboration with our research team and companies. I think it's realistic that different prototypes in soft and hard packaging, such as trays, bottles and bags, will be developed within one to five years," Blennow said.
