Stanford lab turns food waste into cheese using fungal fermentation

A laboratory at Stanford University in California has developed a cheese-like product made entirely from food waste, as part of a broader wave of innovation in which scientists and companies around the world are harnessing fermentation to extract value from discarded ingredients.

Bioengineer Vayu Hill-Maini, who runs the Stanford lab, has been conducting fermentation experiments using fungi — and the results have surprised even him.

"One of the most amazing things that we found recently is that we could take waste and add a few other ingredients in a fungal fermentation and create this delicious cheese that is like a Pecorino or Parmigiano," he says.

What fermentation actually is

Fermentation is a biological process in which organisms convert carbohydrates — such as starch or sugar — into substances like alcohol, without the use of oxygen. It is most commonly associated with baking and brewing, where yeast breaks down sugar into ethanol and carbon dioxide. However, the range of materials capable of fuelling fermentation — known in biology as substrates — is far broader than flour or barley alone.

Armed with the latest biotechnology tools, a growing number of companies are taking food industry by-products that would otherwise be discarded or sold at negligible value and using fermentation to convert them into something useful.

Cocoa shells and flavour mining

UK-based Fermtech is among those leading the charge, transforming cocoa shells — a by-product ordinarily thrown away — into a cocoa powder substitute through fermentation.

"If you were to sniff a bag of cocoa shells, you would be really struck by the intense chocolatey nature of it," says Andy Clayton, Fermtech's chief executive.

Clayton argues it is a missed opportunity to compost or burn food industry by-products rather than deploying microorganisms to break down the harder elements of the plant, making them biologically available to humans whilst preserving their flavours.

"We're kind of like flavour miners," he says.

What to do with three-quarters of a pea

Peas offer another compelling example. Protein accounts for roughly a quarter of a pea's composition, and pea protein has grown considerably in popularity as a plant-based protein source. But what becomes of the remaining three-quarters?

For Spain's MOA Foodtech, that residual material represents "a perfect substrate for fermentation," according to the company's chief executive, Bosco Emparanza. MOA collects data on environmental conditions and available substrates, sequences the genomes of food-industry-appropriate microorganisms, and has used that data to train an artificial intelligence system capable of identifying the optimal combinations of substrates and microorganisms for maximum yield.

Emparanza is struck by how dramatically AI has accelerated the process.

"When we started the company, we were able to develop one bioprocess in two weeks," he says. "Nowadays, the platform can develop 300 bioprocesses per hour."

Using that technology, MOA Foodtech identified the most effective microorganisms for processing the leftover starch and fibre generated by the pea protein industry — material that would typically be sold cheaply for animal feed or simply discarded. The company is now working to return those by-products to the human food chain.

Molasses into premium pet food

Germany's MicroHarvest has developed a confidential process that accelerates fermentation, using by-products of the sugar industry — such as molasses, which is not commonly consumed in Germany — as its substrate.

Rather than allowing sugar producers to redirect this material to farmers as cattle feed, MicroHarvest is collaborating with sugar makers and pet food manufacturers to convert these side streams into premium pet food.

Chief executive and co-founder Katelijne Bekers describes the resulting cat snack, Vegcat, as having an umami flavour profile without the bitterness that can characterise some plant-based proteins.

Singapore's waste-not philosophy

Singapore-based Mottainai Food Tech draws its name and its ethos from the Japanese concept of mottainai — a lament for waste that roughly equates to the English expression "waste not, want not." The company is focused on unconventional and underappreciated ingredients that are both nutritious and widely available across Asia.

Its flagship product is Jiro Meat, a meat substitute derived from okara — the soy pulp left over after the production of tofu and soymilk that is typically discarded. The company has also recently launched a plant-based tuna project, experimenting with various microorganisms to suppress unwanted flavours and amplify desirable ones such as umami and sweetness.

"In five years' time, we hope to be able to have a wide range of ingredients" drawing on the company's fermentation platform, says co-founder Daryl Pek.

Precision fermentation at Stanford

Back at Stanford, Hill-Maini's lab is pushing into the frontier of precision fermentation — a process that involves genetically engineering microorganisms such as moulds to produce a specific material during fermentation. This approach allows scientists to fine-tune not only the flavour and aroma of a food, but also its digestibility.

Hill-Maini notes that some waste products are particularly rich in cellulose, which the human digestive system cannot process. Fungi, however, are capable of breaking down cellulose and converting it into protein as they grow.

"They become kind of a bioconversion machine where they can remove some of those complicated molecules that the human gut cannot digest and convert them into more digestible substances," he explains.

To ensure that laboratory discoveries translate into genuinely appealing food products, the team has embedded a chef in residence and maintains a research and development culinary innovation kitchen.

The Pecorino-like cheese was produced using a Neurospora mould, though the precise waste substrate used remains confidential pending the publication of a research paper. Hill-Maini is nonetheless enthusiastic about what has been achieved.

"You can grate it, it's salty, it has a nice texture, it can be added to pasta. And it's just really cool to see… the fermentation can help it become delicious," he says.