Every Yogurt in the World Contains a Bacterium Named for Bulgaria
Even Greek yogurt lists bulgaricus on the label, a legacy of a 1905 discovery by a Bulgarian scientist.
The Sporkful · Live: The Great Yogurt FeudEvery cup of yogurt in the world, even Greek yogurt, is made with Lactobacillus bulgaricus, a bacterium named for Bulgaria.
To make yogurt of any kind, you need two microbes working together: Streptococcus thermophilus plus Lactobacillus bulgaricus. Together they feed on milk sugar and release lactic acid, which gives yogurt its sour taste and makes milk proteins clump into that thick, soft texture. Add them to warm milk, wait up to 24 hours, and you have yogurt. Different styles just change the ratio. Greek, Icelandic, French, and Lebanese yogurts all contain both.
The Bulgarian name dates to 1905, when Stamen Grigorov, a Bulgarian scientist, carried yogurt from his home village to the Pasteur Institute and became the first person to see its key bacterium. It was named for his country, though the microbe grows naturally around the world and yogurt was probably first made in Central Asia and the Middle East.
As Atanas Valev, a Bulgarian immigrant who makes Tremona yogurt in America, puts it: "It's even on the Greek yogurt. It says bulgaricus, not Greekus."
Questions people ask
If all yogurt uses the same bacteria, why is some yogurt called Greek?
Greek generally refers to straining, not to the cultures. Strained yogurt has much of its liquid whey removed, which makes it thicker and higher in protein per serving. The starting bacteria are still the same two required for all yogurt.
Can I make yogurt at home with just milk and these bacteria?
In principle, yes. With live starter containing both required bacteria, warm milk, and a warm spot to ferment for up to 24 hours, milk will thicken and sour into yogurt. In practice, keeping temperatures steady and starters clean is what keeps the texture and flavor consistent.
Does Bulgarian yogurt taste different if it uses the same bacteria as other yogurts?
Yes. Makers adjust the ratio of the two bacteria, plus fat level and straining, to change flavor and texture. Bulgarian-style yogurt generally uses a higher proportion of Lactobacillus bulgaricus.