A cookie made from plastic sounds like a joke, but researchers at Southern Illinois University Carbondale say it could become food.
The team has developed cookies called µBites, pronounced “microbites”, as part of work that started in NASA’s Deep Space Food Challenge. They presented the research at a symposium organised by the American Chemical Society in Chicago on Monday.
“Converting (biodegradable) food-grade plastic into food is feasible,” Lahiru Jayakody, microbiologist at SIU, told ScienceAlert.
He said the µBites system is “a tunable and portable device that integrates all necessary components.”
“These units could be deployed in submarines or disaster relief vehicles to produce on-demand, on-site food,” he said.
“The process is particularly suited for using carbon waste in extreme environments such as deserts, the Arctic, or the Antarctic to make food, and yes, potentially one day on Mars or the lunar surface.”
The process starts with oxidative hydrothermal dissolution, developed at SIU. It uses oxygen and water under intense heat and high pressure to break materials down into their carbon building blocks.
The team used that process on polyethylene terephthalate, or PET, plastic, along with agricultural waste including corn stalks and leaves, to produce a liquid feedstock.
That liquid is then fed to cultured yeast, which converts it into “nutritious food slurries”.
Researchers then engineered different strains of yeast to turn feedstocks into ingredients including proteins, lipids, vitamins, aromas, colourings and flavourings.
One strain was engineered to produce vanillin for vanilla scent and flavour. Another was designed to make beta-carotene, the orange pigment found in carrots that the body converts into vitamin A.
Those ingredients are combined into a raw dough, loaded into a 3D food printer and piped out layer by layer in a consistent shape. The cookie is then cooked in a microwave to harden it.
No-one has been allowed to try one yet because safety tests are still underway. Blind sensory tests suggested the cookies smelled nice and had a pleasing texture to the touch.
“We have comprehensively analyzed the food products we created in the lab, as well as through accredited third-party laboratories, to ensure µBites cookies are free from toxic chemicals, heavy metals, allergens, and food pathogens,” Jayakody told ScienceAlert.
“We are conducting simulated digestive studies and other necessary analyses in preparation for human trials.”
In its current form, the system takes a day or two and converts more than 50 percent of the carbon from waste materials into food products, according to the team.
“With future iterations and R&D efforts, we could recirculate the unconverted carbon to achieve nearly 100 percent conversion,” Jayakody said.
“The system is designed to achieve a zero-waste concept; however, approximately 10 percent of the carbon material may be released as waste gas or remain unconverted throughout the process.”
The process currently involves 33 steps, but the equipment can be self-contained and portable enough for use where space and resources are limited. The team says a major hurdle is getting it to work in microgravity.
Jayakody said the idea is not limited to cookies.
“We made cookies as a proof of concept, but the food ingredients can also be used to produce other food items that require protein, aroma, and vitamins, such as milk alternatives and meat alternatives,” he said.
“Additionally, we are exploring the use of µBites in feed manufacturing.”
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