"Today's yogurts are typically made with just two bacterial strains," says senior author Leonie Jahn from the Technical University of Denmark. "If you look at traditional yogurt, you have much bigger biodiversity, varying based on location, households, and season. That brings more flavors, textures, and personality."

Red wood ants (Formica species) can be found crawling through the forests of the Balkans and Turkey, where this yogurt-making technique was once popular. To better understand how to use these ants to make yogurt, the researchers visited co-author and anthropologist Sevgi Mutlu Sirakova's family village in Bulgaria, where her relatives and other locals remember the tradition.

"We dropped four whole ants into a jar of warm milk by the instruction of Sevgi's uncle and community members," recalls lead author Veronica Sinotte of the University of Copenhagen, Denmark. The jar was then tucked into an ant mound to ferment overnight. By the next day, the milk had started to thicken and sour. "That's an early stage of yogurt, and it tasted that way as well."

The researchers, who tested the yogurt during their trip, described it as slightly tangy, herbaceous, and having flavors of grass-fed fat.

Back in Denmark, the team dissected the science behind the ant yogurt. They found that the ants carry lactic and acetic acid bacteria. Acids produced by these bacteria help coagulate the dairy. One type of these bacteria was similar to that found in commercial sourdough.