Food waste can be used to make biodegradable plastic

Americans throw away staggering amounts of food waste. The U.S. Department of Agriculture estimates that 30 to 40 percent of the nation’s food supply never gets eaten. Much of it winds up in landfills, where it rots and releases methane and carbon dioxide.

At the same time, the world is drowning in plastic. Bottles, bags, and film break apart into microplastics that seep into water, soil, and eventually – us.

Now, imagine diverting even a slice of that wasted food and using it to make biodegradable plastic that won’t linger for centuries. In a new study, a research team at Binghamton University (SUNY) demonstrates that this future is within reach.

A new purpose for waste

The project was led by graduate researcher Tianzheng Liu, working with Professor Sha Jin and a team in the Thomas J. Watson College of Engineering and Applied Science.

Jin’s interest in food waste sharpened in 2022 after she received a New York State grant to explore new uses for discarded food.

“We can utilize food waste as a resource to convert into so many industrial products, and biodegradable polymer is just one of them,” she said.

“We’re aiming not only to valorize food waste but also to reduce manufacturing cost of this eco-friendly polymer. There are also different options, like generating biofuels and biochemicals.”

Plastic from food and bugs

Making biodegradable plastics today is often expensive. Producers typically start with refined sugar feedstocks and grow microbes in pure cultures – steps that add cost and limit scale.

The Binghamton team took a different approach. The researchers fermented food waste to produce lactic acid (a carbon source) and added ammonium sulfate for nitrogen.

The resulting broth was fed to Cupriavidus necator, a bacterium known for stockpiling carbon as polyhydroxyalkanoate (PHA).

The cells build PHA as internal storage granules. Researchers can recover roughly 90 percent of what the microbes produce and form it into films, packaging, or molded items that biodegrade under the right conditions.

From stem cells to sludge

Liu came to the project with a stem cell background, so pivoting to industrial microbiology meant a steep learning curve. “The bioconversion of food waste into organic acids was a relatively easy one,” he said.

“Cultivation of the plastic-producing bacteria was hard, because at the beginning I didn’t have experience with bacteria fermentation for producing biopolymer. At every move, I felt like something was not what I expected.”

Those frustrations led to tweaks in nutrient balance, fermentation timing, and downstream recovery that now form the backbone of the team’s published method.

Dining halls join the mission

Binghamton University Dining Services and food contractor Sodexo supplied the waste stream that fed the experiments.

“I talked to the sustainable officer at the university and learned that SUNY doesn’t allow landfill food waste – that’s the policy,” she said. “Each campus is expected to solve the problem. At Binghamton, the dining halls give wasted food to farmers to feed their livestock.”

“I thought maybe we could try to directly convert that food waste into biodegradable plastic. There was little information from research publications about the feasibility of this idea, so we felt like maybe that was the gap we could work on.”

Food waste proves dependable

Industrial recycling projects live or die on logistics. The team tested whether they needed to process the collected food scraps right away.

The results showed that the material can sit for at least a week without harming the bioconversion, giving haulers and processors some breathing room.

“We discovered that the process is very robust, as long as we have different types of food mixed in at the same ratio,” Jin said. “We control the temperature and the pH during fermentation, and those conditions encourage organic acid-producing bacteria to grow.”

Fermenting food produces solids as well as acids. Rather than discard the leftover paste, Jin’s group is developing it into an organic fertilizer that could replace some synthetic blends.

Closing that loop would squeeze yet more value from campus scraps while cutting chemical inputs on fields.

Lunch today, package tomorrow

The lab results are promising, but the real impact depends on scale. Jin’s next goal is to ramp up the process and confirm that yields, costs, and product quality hold steady in larger reactors and more variable waste streams.

For that, the group will seek additional grants or an industry partner ready to turn cafeteria leftovers into packaging that composts instead of persisting.

Food waste and plastic waste are two massive problems. This work hints that, with the right microbes and engineering, yesterday’s lunch could become tomorrow’s earth‑friendly packaging.

The study is published in the journal Bioresource Technology.

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