Food for thought after plaudits for berry good creation

University of Queensland researchers have developed with industry a biodegradable plastic fermented from bacteria and strengthened with Australian wood fibres.

Luigi Vandi and Vince Mathel have successfully tested their biocomposite as a strawberry punnet that breaks down in soil, freshwater, the ocean, and in compost. Picture: Aubrey Jonsson

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University of Queensland researchers have developed a biodegradable plastic fermented from bacteria and strengthened with wood fibres, which could replace the 580 million plastic punnets used for strawberries each year.

The bioplastic developed by PhD candidate Vincent Mathel and Dr Luigi Vandi from the School of Mechanical and Mining Engineering is a commercially-viable alternative to petrol-based plastics, and has already been manufactured into strawberry punnets that successfully biodegrade in soil, fresh water, ocean water and compost.

The pair spent three years perfecting the product at UQ’s Centre for Advanced Materials Processing and Manufacturing with industry collaborators.

Biotech Uluu and local injection moulding firm SDI Plastics then helped to manufacture the 200 strawberry punnets, through “cost-effective, conventional industrial processing techniques, with competitive mechanical properties equivalent to polypropylene and polyethylene,” the proof-of-concept paper published in ‘Composites Part A: Applied Science and Manufacturing’ noted.

Luigi Vandi and Vince Mathel worked with industry over several years to develop the cost-effective bioplastic. Picture: Aubrey Jonsson

Once the punnets were created, Queensland Strawberry Growers Association and LuvaBerry Farm ensured the material met end user requirements.

“Punnets are pretty bad from a sustainability perspective, but they are the only way to effectively ship and sell strawberries without ruining the fruit,” Dr Vandi said.

“We’ve shown we can make a product that could potentially replace the 580 million or so plastic punnets every year.”

Mr Mathel said the material had the same properties as mass-produced packaging while being sustainable and locally produced.

He said the “ultimate goal is to phase out petrol-based plastics”, with hopes the biocomposite could be used for food packaging.

“But bioplastics will play a crucial role as a solution when plastics are unavoidable, especially for short-term applications.”

It was created by blending bacteria-produced biodegradable polyesters, known as polyhydroxyalkanoates (PHAs), and wood fibres from Radiata Pine sawdust. The wood used is abundant, low in cost and improves biodegradation.

“The thing many people don’t realise is that bioplastics are not always bio-based and not always biodegradable – there is a lot of greenwashing,” Dr Vandi said.

“If you are striving for complete sustainability and add natural ingredients to the mix, you can impact the physical qualities of the bioplastic, and its suitability for everyday use. Getting the balance right is very important.”

The team is now working with Phoenix Power Recyclers and its senior environmental scientist Dr Deepak Ipe to collect data on the composting of their packaging once it’s discarded, while looking for financial backing to begin a scaled manufacturing process.