The Skinny on... Yogurt

At the supermarket, we all know where the yogurt is, but do we know what it is? It’s supposed to be good for us, but what’s the best way to get all that nutrition into our diets?

By definition
Briefly put, yogurt is a fermented milk product that most likely originated in Asia — although the first written records put it in Turkey around 1070 A.D. Today, it is made from any milk: cow, goat, sheep, yak, mare, water buffalo or camel, to name the most popular worldwide.

What’s important, what’s not?
Look for yogurts with active, live cultures — in other words, “good” or “friendly” bacterial colonies that haven’t been killed off by pasteurization. These beneficial cultures are sometimes called “probiotics.” They may aid human digestion, help our immune systems and can be used for stomach problems like diarrhea, but more research is needed in this area. Avoid yogurts with added starches, gelatins or tapioca. Yogurt should be naturally thickened from the fermentation process.

How is it made?
Almost all modern yogurt is made with a bacteria starter from another yogurt batch. Like sourdough, it’s a process that has roots far in the past as starters keep getting cultivated from batch to batch. The bacteria eat the naturally-occurring sugar — that is, the lactose. They then produce lactic acid which clots the milk protein to give yogurt its creamy texture. Yogurt’s ensuing acidity keeps bad bacteria at bay. Yogurt can often be kept for up to two months, sealed, in a cold refrigerator.

What’s bifidus?
There are two important bacteria used to make yogurt: streptococcus thermophilus and lactobacillus bulgaricus. In the U.S., yogurt must contain both to be called “yogurt.”

Other bacteria are often added for better taste, texture or health. These include lactobacillus acidophilus and bifidus (which promotes digestive health) and lactobacillus casei (which can enhance the immune system).

What is Greek yogurt?
Basically, it’s strained yogurt, much thicker than most other varieties and usually made from sheep’s milk. The yogurt has been passed through a cheesecloth, linen cloth or other fabric, removing much of the liquid — that is, the whey. To make your own: line a colander with cheesecloth or paper towels. Add the yogurt, then set it over a bowl in the sink for a couple hours. Discard the liquid in the bowl; the resulting yogurt will be higher in protein and lower in lactose.