Student researchers create tasty cookies from plastic waste

Aja Poloju / Southern Illinois University Carbondale

COOKIES could be made tastier using flavourings derived from plastic waste and biomass, a group of young scientists has said following a research project in Illinois, US. 

In a poster presentation at an American Chemical Society conference in Chicago earlier this week, the group of undergraduate and graduate researchers working at Southern Illinois University (SIU) said that they had successfully created vanilla-flavoured cookies in a process using yeast to convert plastic and agricultural waste into edible ingredients.

The work follows a 2024 paper in which SIU scientists reported a microbe-based method to make a basic cookie from waste PET bottles, corn plant stalks and other biomass. The feedstock is initially reacted with water and oxygen at a high temperature and pressure in a process called oxidative hydrothermal dissolution in order to break the waste down into water-soluble carbon molecules that can be processed by microbes. These molecules are then fed to a variety of programmed yeasts, which convert them into proteins, fats and acids, before being combined with starch and fibre and 3D printed into a cookie.

The initial study was partly funded by Nasa’s Deep Space Food Challenge, launched to develop suitable foods for longer space missions. While the final cookies were safe to eat, they had wanted to develop more “attractive, consumer-friendly” snacks, graduate student researcher Sandhya Jayasekara said. Her team, which also included a recent high school graduate, an undergraduate researcher and a PhD student, explored how various strains of yeast could yield different ingredients, producing vanilla flavouring from baker’s yeast and a vitamin A precursor from another strain. 

Global food demand is expected to rise by up to 56% by 2050, according to a 2021 paper in Nature Food, while up to 30% of the world’s population could be at risk of hunger. “The way to address that, I believe, is by using microbes,” said Lahiru Jayakody, an associate professor at SIU who was involved in both studies. 

Meanwhile, the student group said in its conference abstract that the work represents a “promising solution to address both food shortage and plastic pollution simultaneously”. According to the latest survey by plastic recycling trade group RECOUP, in the UK alone 594,000 t of plastic bottles were placed on the market in 2023, just 65% of which were collected for recycling despite the inherent recyclability of PET. Contamination in the waste stream can also mean that 14-37% of collected plastic can be rejected before recycling. 

The cookie research is similar to a study last year in which plastic bottles were converted into paracetamol. Stephen Wallace, a professor of biological sciences at the University of Edinburgh who led the paracetamol study but was not involved in the SIU research, said: “PET plastic is ultimately a rich source of carbon, and biology gives us an extraordinary toolkit for converting that carbon into entirely different and potentially more valuable products. For this study, there are important questions around safety, scalability and public acceptance, but as a concept it is an exciting demonstration of what biological upcycling could achieve.”