The researchers conducted fieldwork in Bulgaria, a region with historical oral traditions of ant yogurt making. They then recreated the ancient technique of making yogurt with ants, creating probably the first scientific documentation of the process

Ant yogurt

Fermented milk is one of the most impactful foods in human history. For millennia, people across the globe have been transforming milk into a variety of fermented products such as cheese, kefir, and yogurt. This fermentation process allows milk to be preserved, making it a stable source of nutrition in diverse climates and conditions. But what drives this transformation is the presence of microbes.

The microbes make the yogurt

The bacteria and enzymes that work together to ferment milk are the true creators of yogurt. Microorganisms such as Lactobacillus species and Streptococcus thermophilus interact with milk sugars to produce lactic acid, which gives yogurt its signature tangy flavor and thick, creamy texture. These microbial processes are responsible for both the preservation and the distinctive taste of fermented dairy products.

The most common way to do it is to simply combine warm milk with the right bacteria. This bacteria, called a starter culture, makes the milk curdle and creates yogurt. In the 20th century, yogurt-making became standardized, with specific strains of bacteria being isolated and used to produce yogurt on a commercial scale. Yet, this industrialization came at the cost of microbial diversity.

Traditional yogurt-making methods, such as those that rely on the local environment (and even insects) were largely forgotten or replaced by streamlined, factory-based processes. For thousands of years before these processes, however, people passed down different methods of making yogurt, depending on their climate, culture, and the ingredients available.

One such forgotten method comes from Turkey and Bulgaria, where some nomadic people were known to use ants to start the yogurt fermentation process. This practice may seem strange by modern standards, but ethnographic evidence suggests that ants — specifically red wood ants (Formica rufa) — were crushed and added to milk when yogurt starters were unavailable. These ants and their associated microbes were believed to trigger the fermentation process, turning milk into yogurt.

This technique was passed down as an oral tradition across generations but has been largely forgotten. That’s why a team led by Veronica M. Sinotte of the University of Copenhagen, Denmark, decided to recreate the technique.

How researchers made ant yogurt

The researchers collected live red wood ants from colonies in Bulgaria, as identified by local community members. The team added four live ants to a jar of warmed raw milk. The milk was hot enough to foster fermentation but not to kill the beneficial microbes carried by the ants. After adding the ants, a cheesecloth was placed over the jar to cover it. This allows air circulation while preventing contamination.

Researchers then buried the milk jar inside the ant colony, covering it completely with the mound material. 26 hours later they retrieved the jar. Finally, they assessed the yogurt’s flavour and pH, and stirred it to observe coagulation.

After a day of fermentation, the milk showed signs of acidification. The pH had dropped to around 5 — lower than fresh milk but not as acidic as fully fermented commercial yogurt. The milk had also coagulated, with the formation of curds at the bottom of the jar. The researchers described the flavor of the yogurt as having a slight tang with herbaceous and grassy notes. This was most likely due to the microbial and chemical contributions from the ants.

The researchers also conducted more controlled experiments in a laboratory setting, using ants collected from colonies in Denmark to ensure repeatability. They created three variations of the yogurt:

• Live Ant Yogurt: This was made using live ants crushed into the milk.
• Frozen Ant Yogurt: Ants were first frozen, then added to the milk.
• Dehydrated Ant Yogurt: Ants were dehydrated before being added to the milk.

The “ant yogurt” produced in the study shared some key characteristics with traditional yogurt, but it was not identical to the yogurt most of us are familiar with.

The science behind ant yogurt

The purpose of the study wasn’t just to test the old tradition, it was also to understand how the ants — and the microbes they carry — contribute to milk fermentation. The key concept here is the idea of the “ant holobiont.” A holobiont refers to a host organism and the community of microbes that live in and on it. In the case of the red wood ants, their holobiont includes bacteria, acids, and enzymes that may be crucial to the yogurt-making process.

These ants carry a variety of lactic and acetic acid bacteria, similar to those found in conventional yogurt cultures, which confirms that this is a valid way to make yogurt. Further analysis revealed that the ant-derived yogurt contained not only lactic acid bacteria but also acetic acid bacteria, both of which contribute to the sourness and preservation of the product.

This newfound understanding of ant yogurt has also sparked interest in the world of haute cuisine. Renowned Danish restaurant Alchemist, a Michelin-star restaurant known for its innovative and science-driven culinary experiments, has embraced the idea of ant yogurt. The chefs at Alchemist developed three unique dishes based on this concept: an “ant-wich” ice cream sandwich, a mascarpone-like cheese, and a clarified milk cocktail.

From ancient food to modern science

The rediscovery of ant yogurt has larger implications beyond its culinary novelty. As food scientists continue to explore the potential of using insects in food fermentation, they are uncovering valuable ecological niches where bacteria and other microorganisms thrive. Insects could serve as sustainable sources of enzymes and bacteria applicable to a wide range of fermented products.

One of the significant advantages of using the ant holobiont for yogurt fermentation is the biodiversity it introduces. Industrial yogurt production tends to rely on a limited number of bacterial strains. This can restrict the range of flavors and textures in the final product. By turning to nature and traditional practices, researchers can tap into a much broader microbial diversity, leading to new flavors and potential health benefits.

As promising as the science of ant yogurt may be, it also comes with challenges. Before ants can be used widely in food products, further research and regulatory approvals are necessary to ensure food safety and consumer protection.

The study was published in bioxiv.