Why traditional ‘ant yogurt’ has scientists salivating

Take away the fruit and honey flavourings, and most yogurts in your local grocery store aisle will taste strikingly similar – because modern yogurt production relies on just a handful of lactic acid bacteria.

But this was not always the case – traditional yogurt-making styles around the world have used a wide variety of microbial sources—objects, environments and even creatures—as fermentation starters.

One surprising inoculum has captured the attention of food microbiologists: the humble red wood ant (Formica spp.), a group of closely related species found across Europe and Asia. Roughly the size of a Tic Tac mint, these ants have long been used to turn milk into yogurt in the Balkans and Turkey—and were rediscovered by happenstance in haute cuisine kitchens in Copenhagen.

Researchers followed the practice from anthills to laboratories to pin down the origin of the ants’ transformative powers, identifying both bacteria and properties of the ants’ own bodies.

“The traditions and cultural threads of our food are important to how we eat now – and how we might eat in the future,” explains lead author of the study Veronica Marie Sinotte, a microbial ecologist and Assistant Professor at the Department of Food Science, University of Copenhagen, Denmark. She believes the richness of the natural world and under-explored traditional practices are important in and of themselves, but also could shed light on ways to improve our food system – making food even tastier, sustainable, and equitable.

When haute cuisine rediscovered the wood ant

At Alchemist – a two-Michelin-star restaurant in Copenhagen where a place at the table starts at DKK 5,400, or about EUR 750 – shock and awe are de rigueur. The six-hour dining experience comprises 50 “impressions”, mini-courses designed to challenge diners’ conception of food.

One of the elements favoured by chef provocateurs at Alchemist and other envelope-pushing restaurants in Copenhagen is the red wood ant, which is of culinary interest because the acids in its body give off a citrusy flavour and, of course, for its shock value to Western diners.

But then the ants accidentally came into contact with some milk, triggering a surprising coagulation. The transformation even surprised Diego Prado Vazquez, head of research and development at Alchemist – the ants seemed to act as a microbial starter turning the milk into yogurt.

That chance finding prompted Vazquez to reach out to Sinotte—who had spent years studying the microbiology of ants—at the Novo Nordisk Foundation Microbial Foods Conference in 2022. The collaboration soon expanded to include food microbiologist Leonie Jahn from Denmark’s Technical University (DTU) and ecologist Rob Dunn, and ultimately led the team to Sevgi Mutlu Sirakova, an ethnographer and doctoral candidate at the University of Munich (LMU), documenting traditional fermentation practices in Bulgaria and Turkey, including the making of ant yogurt.

From anthill to laboratory

In 2023, Mutlu Sirakova invited the group on a field trip to her ancestral home, a remote mountain village in Turkish-speaking Bulgaria. Mutlu Sirakova then guided the trip as both an expert in traditional practices and a translator, allowing the team to engage directly with the knowledge of the local community.

“We met a herder in his 80s or 90s who used to make ant yogurt when he took his cows and goats up into the mountains,” Sinotte recalls. “He would milk the cows and goats, put the milk in a barrel and bury it in the ant colony, which acted as an incubator. The temperature there remains remarkably consistent, staying warm overnight – especially in the mountains – and inevitably acts as an inoculum.”

Based on old memories and recipes, like that from the herder, the research team’s attempts to recreate the recipe produced a rich, thick yogurt with a texture similar to panna cotta – and raised a simple question: how was this possible?

“To understand why it worked, we analysed the ants’ holobiont – the ant itself together with all the microbes it carries on and inside its body,” Sinotte explains.

She discovered that what gets transferred to the yogurt is a combination of bacteria and the ant’s own chemical defences.

Sinotte found the ants were covered with bacteria that convert dairy sugars into lactic acid. Generally, in making yogurt, as this acidity rises, milk proteins called caseins stick together into a soft gel that gives yogurt its thick, spoonable texture.

“Some of the microbes behind modern yogurt may have entered human food culture not through design, but through insects,” Sinotte says.

How ants turn milk into yogurt

Adding Fructilactobacillus alone to a vat of milk would not reproduce traditional Bulgarian ant yogurt, because the ant itself actively shapes the fermentation process. Red wood ants deploy formic acid as a chemical defence, and this compound both influences microbial activity and contributes the citrusy tang that gives ant yogurt its distinctive flavour.

Two of the acid-producing species Sinotte found on the ants are familiar to food scientists. The first is Lactobacillus delbrueckii subsp. bulgaricus, which, as the name implies, was first isolated in 1905 in Bulgaria – after which it was popularised as one of the bacterial species used in industrial-scale yogurt production around the world. Sinotte and colleagues only found this in one case, and thus cannot definitively say that ants are the source of the bacteria found in the yogurt in your local grocery store aisle.

However, the second bacterium they found, which was very common in ants and present in all of the yogurt samples they tested, was Fructilactobacillus sanfranciscensis, known for its role in sourdough bread starters. That came as a total surprise, Sinotte says. “Are ants a potential origin of sourdough bread microbes?”

Invisible biodiversity

If a single ant species may have seeded yogurt and sourdough traditions, the question becomes how many other foundational food technologies emerged from encounters with biodiversity we no longer notice.

“To enjoy our foods is also to recognise our broader connections to other species and traditional food practices” Sinotte says. “Conservation and seeing this interconnectedness is really key.”

“Can we get tastier breads from different ant species or populations?” Sinotte asks.

However, Sinotte cautions not to try this at home: without a cultural history of making ant yogurt, raiding ant hills risks legal trouble and harmful hitchhikers.

“Ants can carry liver fluke – a parasite that can infect mammalian livers and make us humans pretty sick,” she explains.

Instead, we should leave it to the professionals. The team at Alchemist created several dishes to celebrate the red wood ant – the ‘ant-wich,’ composed of ice cream made from sheep milk and live ants; a goat milk and dehydrated ant mascarpone; and a milk wash cocktail featuring ants in place of citrus.