Page 30 - Food & Drink Business Jan-Feb 2020

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An a-peeling waste solution
Researchers from the University of New South Wales have developed a way to turn banana plantation waste into biodegradable and recyclable packaging. Kim Berry writes.
A quest to find an agricultural industry where its waste could be turned into something of value led associate professor Jayashree Arcot and professor Martina Stenzel from the University of New South Wales School of Chemical Engineering to banana plantations.
Arcot says the banana growing industry was a “good contender” because only 12 per cent of the plant is used (the bananas) while the rest is discarded after harvest. Its attractiveness was also increased by its high quality cellulose content and that the plant is an annual.
They were particularly interested in the pseudostems
– the layered, fleshy trunk of the plant – which are cut down after each harvest and mostly discarded on the field. Arcot says: “The pseudostem is ninety per cent water, so the solid material ends up reducing down to about ten per cent.”
The pair researched whether it could be a valuable source of cellulose, which could be used in packaging, paper products, textiles and medical applications for wound healing and drug delivery.
The stem is chopped into pieces, dried at very low temperatures and milled into a very fine powder.
The powder is washed with a chemical treatment to isolate the nano-cellulose, a high value material with a range of applications. Once processed, the material has a consistency similar to baking paper.
Stenzel says one of the applications that was of real interest was single-use food packaging where so much ends up in landfill.”
The material can take a number of different formats in food packaging, depending on the intended thickness.
“Depending on how we pour the material and how thick we make it, we could make the trays that you see for meat and fruit... that is completely non-toxic, biodegradable and recyclable.”
Arcot and Stenzel confirmed in tests that the material breaks down organically after putting ‘films’ of the cellulose material in soil for six months.
The material is also recyclable, with one of the pair’s PhD students proving it can be recycled three times without any change in properties.
“What we’re really wanting at this stage is an industry partner who can look into how this could be upscaled and how cheaply we can make it.”
Tests with food have proven it poses no contamination risks. Stenzel says: “We tested the material with food samples to
see whether there was any leaching into the cells. We didn’t see any of that. I also tested it on mammalian cells, cancer cells, T-cells and it’s all non-toxic to them. So if the T-cells are happy – because they’re usually sensitive to anything that’s toxic – then it’s very benign.”
The team have also looked at cotton and rice growing industries, extracting cellulose from both waste cotton gathered from cotton gins and rice paddy husks.
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“In theory you can get nano- cellulose from every plant, it’s just that some plants are better than others in that they have higher cellulose content,” Stenzel says.
For the banana pseudostem
LEFT: Associate professor Jayashree Arcot, professor Martina Stenzel and research student Kehao Huang.
ABOVE: A sample of the finished product – bioplastic film made from banana pseudostem material.
to be a realistic alternative to plastic bags and food packaging, it would make sense for the banana industry to start processing them into powder, which they could then sell to packaging suppliers, she adds.
“If the banana industry can come on board, and they say to their farmers or growers that there’s a lot of value in using those pseudostems to make into a powder which you could then sell, that’s a much better option for them as well as for us,” Arcot says.
And at the other end of the supply chain, if packaging manufacturers updated their machines to be able to fabricate the nano-cellulose film into bags and other food packaging materials, then banana pseudostems stand a real chance of making food packaging much more sustainable.
“What we’re really wanting at this stage is an industry partner who can look into how this could be upscaled and how cheaply we can make it,” Stenzel says.
Arcot agrees. “I think the packaging companies would be more willing to have a go at this material, if they knew the material was available readily.” ✷
30 | Food&Drink business | January-February 2020 | www.foodanddrinkbusiness.com.au