Regular yogurt beside thick Greek yogurt with a spoon standing upright

What is Greek Yogurt? A Clear Answer

ByCraig Brockie Last updated

What is Greek yogurt?

What is Greek yogurt? It is yogurt that has had part of its liquid whey strained off after fermentation, leaving a thicker food with roughly twice the protein of regular plain yogurt. Cloth bags are traditional; dairies also use centrifuges or membranes. Some “Greek-style” yogurts get their thickness from added milk protein or stabilizers instead.

Greek yogurt vs. regular yogurt: what straining changes

It starts as ordinary yogurt

Greek yogurt begins as regular yogurt: pasteurized milk fermented by Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus until it sets at a pH of 4.6 or lower. Straining then drains away acid whey, a thin liquid of water, milk sugar and minerals, while most of the protein stays in the yogurt. In industry, each kilogram of Greek yogurt leaves 2 to 3 kg of acid whey behind (the same ratio holds in pounds). The methods are compared in How Is Greek Yogurt Made? Explained.

Water, protein and texture

USDA figures for plain whole-milk yogurt show what changes, per 100 g:

Per 100 gRegular plain, whole milkGreek plain, whole milk
Water87.9 g81.3 g
Protein3.47 g9.0 g
Fat3.25 g5.0 g
Total sugars4.66 g4.00 g
Calcium121 mg100 mg

The nonfat pair differs more on sugar: nonfat Greek yogurt has 10.2 g of protein and 3.24 g of total sugars per 100 g, against 5.73 g and 7.68 g in regular nonfat. Calcium falls (110 mg against 199 mg) because calcium bound to milk protein dissolves as yogurt acidifies and leaves with the whey. Serving sizes and fat levels are covered in Greek Yogurt Protein: What You Need to Know.

The result is a thick, spoonable yogurt. When FDA updated the yogurt standard in 2021, it noted that thicker Greek-style yogurt had become as popular as regular yogurt.

Greek, Greek-style and strained: what the name means

In the US, the name has no legal definition. The federal yogurt standard, 21 CFR 131.200, never mentions Greek or strained yogurt, and it allows “other safe and suitable milk-derived ingredients” to raise milk solids, as well as stabilizers. FDA’s 2021 rule said those ingredients let makers reach a desired protein content in Greek-style yogurt before culturing. So a US tub labeled Greek or Greek-style may be strained, fortified with milk protein, thickened with stabilizers such as pectin, gelatin or starch, or made with a mix of these.

Other places are stricter. In Greece the product is known as strained yogurt, traditionally drained in a cloth called a tsantila, and Greek legislation requires at least 5.6% protein from cow’s or goat’s milk (8% from sheep’s milk). In 2014 the UK Court of Appeal ruled that only yogurt made in Greece by traditional methods, without additives, could be sold there as “Greek yoghurt.” The international Codex Alimentarius standard groups these foods as concentrated fermented milks, with protein raised to at least 5.6% before or after fermentation, against a 2.7% minimum for yogurt.

Why the difference matters when you buy, cook or make it

Strained and fortified Greek yogurts can look alike in the tub, so the label does the work:

Greek yogurt with grated cucumber and dill for tzatziki

In the kitchen, thickness is the point. Washington State University Extension says strained yogurt can replace cream cheese, mayonnaise and sour cream in dips, sauces and spreads. For the health research, see Is Greek Yogurt Good for You?

You can also make it. Strain plain yogurt, covered, in the refrigerator at 40°F (4°C) or below; University of Illinois Extension suggests 2 to 4 hours for Greek-style yogurt. Ultimate Health Solutions, the company that publishes this site, recommends checking every hour and expecting roughly half the starting volume. Homemade Greek Yogurt: What You Need to Know covers yield, cost and storage.

Related terms

  • Greek-style yogurt: a label term for thick yogurt that may be strained, fortified with milk protein or thickened; it has no US legal definition.
  • Skyr: a traditional Icelandic food made from skimmed milk. Technically a fresh cheese traditionally made with rennet, it is now made with starter cultures, mainly the two yogurt bacteria, and its whey is removed by centrifuge or ultrafiltration, giving 10 to 15% protein.
  • Labneh: a concentrated yogurt eaten across the Middle East and the Balkans, traditionally strained in a cloth bag and sometimes salted; it typically has 23 to 25% total solids.
  • Yogurt cheese: yogurt strained until spreadable, 8 to 24 hours at home; WSU Extension treats it as another name for labneh.
  • Quark: a soft fresh cheese made by souring skim milk with mesophilic cheese cultures at about 90°F (32°C) rather than yogurt cultures, now usually concentrated by ultrafiltration or centrifuge.
  • Acid whey: the tart liquid drained off, mostly water with about 3.5% lactose and little protein.
  • Plain yogurt: unflavored, unstrained yogurt, the starting point for Greek; see Plain Yogurt: What You Need to Know.

More on Greek yogurt

Sources

Craig Brockie is the founder of Ultimate Health Solutions, the company behind Ultimate Gut, and the author of Ultimate Health, The Ultimate Gut Health Guide and The Unlimited Probiotics Guide. After injuries and chronic health problems in his twenties that conventional care didn’t resolve, he began researching health on his own and has studied natural health for 30 years. He is not a medical professional, and his articles are general information, not medical advice.

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