Turning coffee grounds into coffee cups

Coffee grounds could be used to create biodegradable plastic coffee cups thanks to new research from Macquarie University.

The process converts the spent coffee grounds into a lactic acid which is then turned into a plastic, however the method is still being refined by researcher Dominik Kopp.

Related stories:

Because 50 per cent of coffee grounds are made up of sugars, they can be converted into bio-based chemicals.

The method was inspired by a metabolic pathway that is thought to exist in an evolutionary ancient organism, which lived in hot and extremely acidic environments.

“Australians consume six billion cups of coffee every year, and the coffee grounds used to make these coffees are used only once and then discarded,” says Mr Kopp.

“In Sydney alone, over 920 cafes and coffee shops produced nearly 3,000 tonnes of waste coffee grounds every year.

“Ninety-three per cent of this waste ends up in landfill, where it produces greenhouse gases that contribute to global warming.”

Mr Kopp sources the coffee grounds from one of the shops on Macquarie’s campus and took them back to the lab.

“We assembled a synthetic pathway to convert the most abundant sugar in the coffee grounds, mannose, into lactic acid,” he says.

“Lactic acid can be used in the production of biodegradable plastics, offering a more sustainable and environmentally-friendly alternative to fossil fuel-derived plastics.

“You could use such plastics to make anything from plastic coffee cups to yoghurt containers to compost bags to sutures in medicine.”

His next step will be to further refine the conversion pathway and improve the yield of lactic acid.

“I think my project is one of many interesting approaches on how to use synthetic biology in a responsible manner for the development of a more sustainable and greener industry that doesn’t rely on crude oil,” says Dominik.

“The simple idea that we are converting waste into a valuable and sustainable product is extremely exciting!”