Monash University researchers are turning sugars from discarded food into natural plastic films that could one day replace petroleum-based packaging.
Can naivety be a blessing in disguise? When Edward Attenborough moved from Tasmania to Melbourne to pursue a degree in science and chemical engineering, making an impact was at the forefront of his mind.
“In my naïve mind, all I could think about was finding ways to fix climate change,” he said.
Now a PhD candidate in the Department of Chemical and Biological Engineering, Attenborough joined Food & Beverage Industry News to share research that could change the future of food waste and packaging.
The problem
Global plastic production exceeds 400 million tonnes each year. Conventional plastics, such as polyethylene and polypropylene, are known for their durability and cost-effectiveness; however, their environmental impact has become increasingly difficult to ignore.
Combatting this, the industry has seen improvements in innovation for recyclable options and other sustainable initiatives. While the effort is commendable and shows a sustainable direction, it doesn’t encompass solutions across all plastics.
“The biggest problem we have at the moment is that while hard plastics can be recycled quite cost efficiently, soft plastics can’t,” said Attenborough.
In Australia, soft plastics are rarely recycled, with most ending up in landfill or being incinerated. Thin films break down into microplastics under exposure to sunlight and weather, further contributing to pollution in waterways and soil.
“There are also bioplastics, known for their biodegradable qualities,” he added. “However, they are industrially biodegraded.”
Bioplastics made from polylactic acid (PLA) have not provided a complete solution. Although these materials can biodegrade, they require controlled industrial composting conditions with specific temperature and humidity levels. In natural environments such as oceans, they can persist for years, failing to achieve their intended environmental benefit.
Attenborough and senior lecturer Dr Leonie van ‘t Hag addressed this issue, looking into what he described as the “next generation of plastics” – bioplastics. The two led a study that provides a framework for designing bioplastics for temperature-sensitive packaging, medical films and other products.
The project focuses on developing biodegradable and compostable materials that can degrade naturally in the environment.
What the study showed
The research builds on previous scientific work into microbial plastics, also known as bacterial polymers. The microbial polymers under investigation belong to a class known as polyhydroxyalkanoates (PHAs). These are produced naturally by bacteria and possess the ability to degrade completely in soil, home compost, and marine environments.
The research teams put two soil-dwelling bacteria – Cupriavidus necator and Pseudomonas putida – on a carefully balanced diet of sugars with the right blend of salts, nutrients and trace elements to produce biopolymers.
“When humans eat too much, we put on weight,” said Attenborough. “The microbes make these biopolymers in the cell when they consume too many fats or sugars.”
By storing the energy as biopolymers within their cells from the fats and sugars, the Monash team has been able to encourage the cells to produce larger quantities of polymer that can be extracted and processed into thin plastic films.
Image: OlegDoroshin/stock.adobe.com
Usually only one micron in size, this study showed that it is possible to grow the bacteria up to 30 microns, 30 times larger than their usual form. These biopolymers stored in the bacteria can be removed and transformed into thin films similar in thickness to cling wrap or pallet film.
“What’s exciting is that these films are home compostable and fully marine biodegradable,” he said.
With a focus on thin films, the team investigated how adjusting the chain length of these polymers affected the properties of the film. By blending polymers with different chain lengths, the researchers explored how these variations influenced flexibility, melting temperature and crystallinity.
By comparing the stiff plastic made by C. necator with the softer, more flexible version from P. putida, the study demonstrates how blending the two can tune film properties like crystallinity and melting point, while maintaining strength and flexibility.
Where food waste comes in
The research shows that PHAs can be produced from simple sugars such as glucose and fructose, which can be derived from waste bread, potatoes, fruit or vegetables. Attenborough calls them “simple” sugars.
“You can get these sugars from waste products that have a lot of starch, like bread or potato,” he said.
Enzymes can convert and strip the starch down into glucose units. This process could turn agricultural and food manufacturing waste into a valuable resource, aligning with circular economy principles. In regions such as Victoria, where agricultural processing generates large amounts of fruit and vegetable by-products, the potential for sourcing these sugars is strong.
Perfection takes time
While exciting, the research is still in progress.
“As of now, we’re still investigating the barrier properties of the materials,” Attenborough said.
According to him, several technical challenges remain. Thin plastics currently used for fruit and vegetables are effective due to good barrier properties where water cannot permeate through. The bioplastics mirror this property due to being hydrophobic, but their flexibility with oxygen transfer is still limited.
For products such as fresh meat or produce, maintaining low oxygen permeability is essential to extend shelf life. Conventional food packaging often uses multilayer plastic structures, with up to five different layers engineered to optimise these properties. However, these complex layers are also what make them nearly impossible to recycle.
While recyclability is important, the sustainable alternative must perform at similar or better levels to fully replace the original. In this case, another limitation appeared.
“We found that the plastic wasn’t very stretchy,” said Attenborough.
Cling and pallet films have 100 to 200 per cent stretch elongation at break. With the bioplastic films, the maximum elongation was 10 per cent. Improving flexibility without compromising biodegradability will be a critical focus for future research.
However, the Monash team is persistent. As this research builds on 50 years of scientific study, Attenborough said it is a collaborative process that brings the industry closer to a goal.
“We’re all just iterating and building,” he said. “That’s how great research is made.”
These limitations are only for thinner applications. Promising examples of thicker applications are already in use. Companies in the United States have successfully created bottles made entirely from PHA that compost under standard conditions. Others have used PHA coatings in coffee cups, replacing the traditional polyethylene liner that prevents recycling.
The researchers plan to investigate plasticising techniques and polymer blending to enhance flexibility and barrier control moving forward.
A compostable cycle
In the next five to ten years, the research team aims to scale production and further refine the material for specific packaging needs.
“My goal would be to see a lot of single-use packaging materials move to a compostable cycle,” said Attenborough.
Soft plastics remain a priority because they are difficult and costly to recycle and often end up in landfill or the environment. According to him, soft plastics do not yet have a proper or economically viable recycling system in place.
Paper-based packaging with plastic liners is another target area. These products are often marketed as sustainable due to their paper content, but the plastic film lining prevents them from being composted or recycled effectively. Replacing such liners with PHA could make them compostable and eliminate the misleading perception of sustainability that currently surrounds paper-plastic hybrids.
“It’s not just about replacing material with something that composts,” Attenborough said. “It’s about trying to limit landfilling and production of microplastics.”
Attenborough sees this technology as a critical step towards a circular packaging economy. He believes that manufacturers and consumers alike should consider not only the function of packaging materials but also their end-of-life pathway. Current recycling technologies can only reprocess plastics a limited number of times, and contamination from food residues often reduces their quality.
The Monash team’s vision is to create packaging materials designed with their disposal in mind, ensuring that when they reach the end of their life, they can safely return to the environment. By reducing microplastic formation through food waste, microbial plastics could help move the food and beverage sector closer to a truly circular model.
“We must properly consider the end of life and how it’s going to break down as we cannot infinitely recycle petroleum plastics,” said Attenborough. “We hope to work towards this future with single-use thin film bioplastics.”