fermentation

Scientists revive old Bulgarian recipe to make yogurt with ants

Fermenting milk to make yogurt, cheeses, or kefir is an ancient practice, and different cultures have their own traditional methods, often preserved in oral histories. The forests of Bulgaria and Turkey have an abundance of red wood ants, for instance, so a time-honored Bulgarian yogurt-making practice involves dropping a few live ants (or crushed-up ant eggs) into the milk to jump-start fermentation. Scientists have now figured out why the ants are so effective in making edible yogurt, according to a paper published in the journal iScience. The authors even collaborated with chefs to create modern recipes using ant yogurt.

“Today’s yogurts are typically made with just two bacterial strains,” said co-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.”

If you want to study traditional culinary methods, it helps to go where those traditions emerged, since the locals likely still retain memories and oral histories of said culinary methods—in this case, Nova Mahala, Bulgaria, where co-author Sevgi Mutlu Sirakova’s family still lives. To recreate the region’s ant yogurt, the team followed instructions from Sirakova’s uncle. They used fresh raw cow milk, warmed until scalding, “such that it could ‘bite your pinkie finger,'” per the authors. Four live red wood ants were then collected from a local colony and added to the milk.

The authors secured the milk with cheesecloth and wrapped the glass container in fabric for insulation before burying it inside the ant colony, covering the container completely with the mound material. “The nest itself is known to produce heat and thus act as an incubator for yogurt fermentation,” they wrote. They retrieved the container 26 hours later to taste it and check the pH, stirring it to observe the coagulation. The milk had definitely begun to thicken and sour, producing the early stage of yogurt. Tasters described it as “slightly tangy, herbaceous,” with notes of “grass-fed fat.”

Rice could be key to brewing better non-alcoholic beer

beer, chemistry, fermentation, Science / Beth Washington / July 3, 2025

small glass of light colored beer with a nice foam head — Rice enhances flavor profiles for nonalcoholic beer, reduces fermentation time, and may contribute to flavor stability. Credit: Paden Johnson/CC BY-NC-SA

He and his team—including Christian Schubert, a visiting postdoc from the Research Institute for Raw Materials and Beverage Analysis in Berlin—brewed their own non-alcoholic beers, ranging from those made with 100 percent barley malt to ones made with 100 percent rice. They conducted a volatile chemical analysis to identify specific compounds present in the beers and assembled two sensory panels of tasters (one in the US, one in Europe) to assess aromas, flavors, and mouthfeel.

The panelists determined the rice-brewed beers had less worty flavors, and the chemical analysis revealed why: lower levels of aldehyde compounds. Instead, other sensory attributes emerged, most notably vanilla or buttery notes. “If a brewer wanted a more neutral character, they could use nonaromatic rice,” the authors wrote. Along with brewing beers with 50 percent barley/50 percent rice, this would produce non-alcoholic beers likely to appeal more broadly to consumers.

The panelists also noted that higher rice content resulted in beers with a fatty/creamy mouthfeel—likely because higher rice content was correlated with increased levels of larger alcohol molecules, which are known to contribute to a pleasant mouthfeel. But it didn’t raise the alcohol content above the legal threshold for a nonalcoholic beer.

There were cultural preferences, however. The US panelists didn’t mind worty flavors as much as the European tasters did, which might explain why the former chose beers brewed with 70 percent barley/30 percent rice as the optimal mix. Their European counterparts preferred the opposite ratio (30 percent barley/70 percent rice). The explanation “may lie in the sensory expectations shaped by each region’s brewing traditions,” the authors wrote. Fermentation also occurred more quickly as the rice content increased because of higher levels of glucose and fructose.

The second study focused on testing 74 different rice cultivars to determine their extract yields, an important variable when it comes to an efficient brewing process, since higher yields mean brewers can use less grain, thereby cutting costs. This revealed that cultivars with lower amylose content cracked more easily to release sugars during the mashing process, producing the highest yields. And certain varieties also had lower gelatinization temperatures for greater ease of processing.

International Journal of Food Science, 2025. DOI: 10.1080/10942912.2025.2520907 (About DOIs)

Journal of the American Society of Brewing Chemists, 2025. DOI: 10.1080/03610470.2025.2499768

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