Turning banana waste into food packaging

On 22 May 2020 — International Day of Biodiversity — the UNSW Sydney celebrated some of its recent research that is inspiring positive change in how we tackle global problems, whether it be managing climate change, bushfires or plastic waste.

One of the research projects celebrated on the day was an ‘a-peeling’ packaging solution made from banana plants, which could be suitable for the food industry.

Associate Professor Jayashree Arcot and Professor Martina Stenzel were searching for ways to convert agricultural waste into something that could value-add to the industry it came from, while potentially solving problems for another. The researchers discovered a novel way to turn banana plantation waste into biodegradable and recyclable packaging material.

“What makes the banana-growing business particularly wasteful compared to other fruit crops is the fact that the plant dies after each harvest. We were particularly interested in the pseudostems — basically the layered, fleshy trunk of the plant which is cut down after each harvest and mostly discarded on the field. Some of it is used for textiles, some as compost, but other than that, it’s a huge waste,” Associate Professor Arcot said.

Arcot and Stenzel researched whether the pseudostems could be used in packaging, paper products, textiles and medical applications, such as wound healing and drug delivery. Using a supply of pseudostem material from banana plants grown at the Royal Botanic Garden, Sydney, researchers began extracting cellulose to test its suitability as a packaging alternative.

“The pseudostem is 90% water, so the solid material ends up reducing down to about 10%. We bring the pseudostem into the lab and chop it into pieces, dry it at very low temperatures in a drying oven and then mill it into a very fine powder,” Associate Professor Arcot said.

The researchers then take this powder and wash it with a very soft chemical treatment. When processed, the material has a consistency similar to baking paper. Depending on the intended thickness, the material could be used in a number of different formats in food packaging.

Researchers have confirmed in tests that the material breaks down organically after putting ‘films’ of the cellulose material in soil for six months. They also tested that it is recyclable and poses no contamination risks for food applications.

For the banana stem to be a realistic alternative to plastic bags and food packaging, the researchers said it would make sense for the banana industry to start the processing of the pseudostems into powder, which they could then sell to packaging suppliers.

At the other end of the supply chain, if packaging manufacturers update their machines to be able to fabricate the nano-cellulose film into bags and other food packaging materials, then banana pseudostems could make 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 cheap we can make it,” Professor Stenzel said.

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