© Denzil Green
Yoghurt is milk to which a bacteria (“Lactobacillus bulgaricus”) has been added, which thickens the milk, helps to extend its shelf life, and gives it a tangy taste. The bacteria feeds on the lactose sugars in the milk, changing them into lactic acid, which in turn curdles the milk proteins which thickens it into Yoghurt.
There are many varieties. The variety range starts with the milks it can be made from: buffalo, goat, sheep, soy, yak, camel and of course, cow milk, which is what almost all of our commercial Yoghurt is made from. From there, they can be whole milk, low-fat or skim, and active cultures or dead cultures. Yoghurt made from goat’s milk has a sharper taste than that made from cow’s milk.
The active cultures are sold with the bacteria still live in them, for the health benefits to our stomachs. The ones with dead cultures, though are course they are never labelled like that, are heat-treated to destroy the cultures on purpose, which extends the shelf-life of the product.
Sometimes, a tub of whole milk Yoghurt may have a thicker, creamier layer on top. To reduce the fat content of the Yoghurt, you can skim this off with a spoon — and then eat it, as it is delicious.
The thing to remember about dairy is that the higher the fat content, the more heat you can subject it to. It’s lower fat things — like Yoghurt, which at the most will have 4% butterfat, and usually 3.5% — that will curdle, as opposed to say, double-cream, which can have 50% butterfat. But I like the idea of cooking with Yoghurt, precisely because it is lower fat, and because of the zing it can add to a dish. Here are some tips:
- Bring Yoghurt to room temperature before using;
- Whenever possible, add Yoghurt at the end of cooking, such as when you are making a soup. But if it’s a curry sauce you are doing, oftentimes the Yoghurt is best added the beginning so that all the flavours marry. In which case, stabilize the Yoghurt first with the flour method (below).
- Mix in a bit of flour. Any flour will do; in India, chickpea flour is used because it also adds flavour. The flour will keep the Yoghurt from curdling even if it should boil. Stir the flour into a bit of water first, then introduce into the Yoghurt;
- If you are substituting Yoghurt for a much thicker cream, or if your Yoghurt just seems too runny, and you want to make your Yoghurt thicker, stir a little powdered milk into it;
- When using Yoghurt instead of milk or cream in making pastry or cakes, for every cup of Yoghurt add a teaspoon of baking powder;
- In recipes that call for mayonnaise, try using half mayonnaise and half Yoghurt;
- If you are concerned about keeping the active bacteria alive during cooking, the temperature mustn’t go above 45 Celsius. If it goes above that; well, just think of all the other health benefits you are still enjoying anyway.
When making your own Yoghurt, the shorter the setting time, the sweeter the Yoghurt will be: the longer it is, the tarter the Yoghurt will taste.
Sour cream; any form of fresh cream; crème fraîche; puréed cottage cheese; buttermilk
Yoghurt with active cultures can aid digestion, help restore healthy bacteria levels in the stomach (especially important after a period of being on antibiotics) and because the lactose in it has been converted, can usually be eaten by people who have trouble with milk (but don’t count on this: depending on the brand, anywhere from 20% all the way up to 80% of the lactose can remain).
It is a good source of protein, calcium, riboflavin, phosphorus and vitamin B12
Beyond that, some of the heath benefits touted for Yoghurt are:
- Low in fat;
- Restores beneficial bacteria to the stomach (if active culture Yoghurt);
- More digestible than milk;
- Fights acne (when consumed, not applied);
- Cures bad breath (other sources believe Yoghurt causes it).
On some Yoghurt tubs, you may see the phrase “contains clockwise rotating lactic acid”. One type of lactic acid rotates clockwise, the other counter-clockwise. The clockwise is more easily digested.
3/4 cup of Yoghurt = 6 ounces fluid /175 ml and by weight = 6 oz / 170g
1 cup of Yoghurt = 8 ounces fluid = 8 ounces weight / 225g
1 200g tub = 7 ounces weight
(note: Yoghurt tub weights given on the containers in oz are usually oz by weight, rather than liquid oz).
Keep Yoghurt refrigerated in a sealed plastic container (all things being equal, the tub it came in.)
You can freeze full-fat Yoghurts for use in cooking afterward, but freezing active Yoghurts will render your active bacteria quite inactive, as in morto. Defrost slowly, whisk before using as may separate a bit.
The Roman historian, Pliny the elder, may have written about Yoghurt: “the barbarous nations … understand how to thicken milk and form therefrom an acrid kind of milk with a pleasant flavour”. 
The Turks were making it in the 11th century.
The “Lactobacillus bulgaricus” bacteria was identified by a doctor named Stamen Grigorov (1878–1945) in 1905. The “bulgaricus” part of the name does not mean, as some mistakenly assume, that Yoghurt originated in Bulgaria. Instead, it’s a tribute to Grigorov, who was Bulgarian.
Commercial production of Yoghurt was begun in Barcelona in 1919 by Isaac Carasso. He named his business after his son Daniel, calling it “Danone” (meaning “little Daniel.”) The name was later Americanized to Dannon.
In America, Yoghurt bacteria was being sold by mail order capsules as early as 1907:
“These friendly germs can be purchased by mail in capsules — 50 million in a capsule — four dozen capsules in a box sent to any address on receipt of one dollar. They are sold only under the trade name of YOGHURT. An interesting book describing these friendly germs, known to the trade as YOGURT, will be mailed free upon request by the Yogurt Company, 11 College Hall, Battle Creek, Michigan.” — Advertisement: “Friendly Germs for sale by mail.” New York Times. 24 November 1907. Page 27. Column 7.
Advertising for the capsules as a health treatment picked up in the 1920s:
“Wanted — Lady or Gentleman in every town for local information. Good income. No canvassing. Yoghurt Co., Bellingham, Washington.” — Advertisement in “Bode Bugle”. Bode, Iowa. 16 July 1921. Page 7. Column 6.
“Are you underweight? We can build you up with our drugless Fresh building treatement taken in your own home. Our emaciation expert will forward you explicity instructions for your own individual case. Free literature. Yoghurt Sanitarium. Dept F. So. Belllingham, Washington.” — Advertisment in: Oakland Tribune. Oakland, California. 19 November 1922. Page 85.
In 1929, an Armenian couple named Sarkis and Rose Colombosian, living in Andover, Massachusetts, began selling from their home jars of Yoghurt made from an Armenian recipe. They called their dairy “Colombo and Sons Creamery.” 
By the 1940s, Yoghurt had become popular in New York. Clementine Paddleford wrote in 1946, “Twenty years ago the product was introduced as a health food in New York, and slowly but surely it’s catching on here. Now one firm alone is selling 60,000 jars weekly.”  [Ed: the firm she is referring to is Dannon, which had opened a branch in New York in 1942.]
Yoghurt is only now (2004) slowly becoming popular in India.
Literature & Lore
“One of the important makers was the Dannon Company of Paris which, the year the war started, was turning out around 80,000 5 ½-ounce jars of yogurt a day, both fruited and plain. Daniel Carasso, son of the firm’s founder, transferred the business here in 1942. Now the product so carefully made in a modern laboratory factory in Long Island City has created a Manhattan boom in the consumption of this tart milk custard. Possibly the internationalizing influence of the United Nations personnel has had something to do with the rush of business. When the Assembly was still in session the United Nations Cafeteria sold 300 jars of yogurt a day. United Nations or not, yogurt is selling in unheard-of volume in some 2,000 outlets in the metropolitan New York area with a special route coverage through New Jersey and Westchester. Now plain platinum-blonde yogurt will be seen everywhere with its sister, the daring strawberry blonde.” — Paddleford, Clementine (1898 – 1967). Food Flashes Column. Gourmet Magazine. July 1948.
 The Natural History of Pliny, tr. John Bostock and H.T. Riley, London: Bell, 1856-93, Volume 3, p. 84.
 Business Wire Magazine. Colombo Yogurt – First U.S. Yogurt Brand – Celebrates 75 Years. 13 May 2004.
 Paddleford, Clementine (1898 – 1967). Food Flashes Column. Gourmet Magazine. August 1946.
Yonan, Joe. Yogurt: The culture catches on. The Boston Globe, 11 August 2004.