Yogurt Cultured Bos taurus milk
Strained overnight through cloth it thickens to the body of a cream sauce.
2 recipes on this site
In the kitchen
Under heat
Its proteins split if it hits direct high heat or acid too fast — stir it into a hot sauce off the heat, or temper it first.
Against air
The surface skins over and can weep liquid if left uncovered; that liquid is whey, not spoilage — stir it back in.
In storage
Sealed in the fridge, it keeps for a couple of weeks past opening if you use a clean spoon each time.
At the shop
Check for a thin layer of liquid on top through the lid if you can — a little is normal, a lot means it’s been sitting.
Which variety, for what
- Regular / plain
- Looser and tangier — better whisked into a dressing or marinade.
- Greek / strained
- Thicker and milder from having whey removed — closer to sour cream in body, and a reasonable substitute for it.
Beyond the kitchen
TWO BACTERIA, BY DEFINITION
Yoghurt is milk fermented by Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. The two work in sequence, each producing compounds the other uses, and in most jurisdictions a product cannot legally be called yoghurt without both.
STRAINING IS THE WHOLE TRICK
Greek, labneh and skyr are all made by draining whey from set yoghurt. It takes roughly three or four litres of milk to make one of strained yoghurt, and the whey removed is a significant industrial by-product in its own right.
A BULGARIAN DISCOVERY
Stamen Grigorov identified the bacillus in Bulgarian yoghurt in 1905 while studying in Geneva, and the organism carries the country's name. Bulgaria regards yoghurt as a matter of national identity and maintains a research institute devoted to it.
IT WILL NOT BOIL
Yoghurt splits when heated because its proteins are already acid-set and coagulate further with heat. Cuisines that cook with it — Turkish, Persian, Indian — stabilise it first with cornflour or egg, and stir in one direction while it comes up to temperature.
A longer history
Fermented milk is almost certainly as old as dairying itself, and probably older than deliberate cheesemaking: milk left in a warm skin container ferments on its own. The practice is documented across Central Asia, the Near East, the Balkans and India for thousands of years, and Indian texts name dahi among ancient foods.
Because fermentation converts much of the lactose, yoghurt was the form in which milk was digestible for populations without lactase persistence — which is why fermented dairy, rather than fresh milk, is traditional across so much of Asia, the Caucasus and the Middle East.
Its industrial history is short and specific. Isaac Carasso began producing it commercially in Barcelona in 1919, naming the company Danone after his son, and initially selling it through pharmacies. Sweetened and fruited versions from the 1930s onward turned it into a mass-market product, and strained Greek-style yoghurt became a major Western category only from the 2000s.
