yogurt

I cannot imagine anything that could replace the magic of yogurt, which transcends cultures and lands. Tea, maybe?

- Hamdi Ulukaya

Intro

Yogurt (yoğurt, Turkish) is a type of fermented milk product (other types include kefir, cultured buttermilk, sour cream, crème fraîche). It is made by adding bacteria/cultures to milk, which causes the sugars (lactose) to ferment, producing lactic acid (lending to the characteristic tang of yogurts) as well as preserving the milk because the low Ph of cultured milk inhibits the growth of other bacteria that might cause spoiling. This also resulted in a product that could be consumed by people who are intolerant to normal milk.

Legend has it that a Turkish nomad on the southern slopes of Mount Elbrus of the Caucauses, on a very hot day, found his pitcher of milk had become what came to be known as yoğurut.

Making yogurt in a nutshell, industrial style: Raw milk is separated by centrifuging and filtering (milk fat globules and solid impurities are separated out from the rest which is in turn separated into skim milk and cream. The cumulative volume of cream that is separated out is measured continuously during this process, so the valve pressure of the skim milk-cream separation chambers can be adjusted accordingly. The whole milk is pasteurized at 55-65°C. While the temperature is still warm, milk homogenization begins (homogenization is optimal at 60°C) and forces the milk through narrow gaps under pressure to break up large flat clumps. Once homogenized, cultures are added, usually in frozen form. All yogurt cultures contain lactobacillus delbrueckii as a base but the various additional strains of yogurt cultures available influence the flavor an texture of the yogurt (they produce different sugars and influence the viscosity). Tetrapak also has an informative page on yogurt production.

Yogurt composition and how they contribute to final taste

• lactic acid: sourness

• acetaldehyde: green apple

• acetic acid: vinegary

• diacetyl: buttery

Types of yogurt

What is known as "Greek" yogurt in the U.S. and parts of Europe is actually strained yogurt, but in Greece, not all yogurts are strained. The difference between Greek yogurt, Turkish yogurt or yogurt from many Balkan countries? Debatable -- and in each of these regions, there are also different types of yogurts. In the end, what we associate with "Greek" yogurt is more a reflection of how products are marketed where we are.

• set

  • production characteristic: yogurt once packaged in cups are left to set without being further disturbed

• stirred (a.k.a. Swiss-style, French, prestirred, preblended)

  • production characteristic:

    • incubated and cooled before adding flavors/packaging; stirred/broken up before packaging

    • culture strains that lend well to this type are L. bulgaricus and S. thermophilus because they add viscosity

• strained

  • Skyr

    • New on the market is Icelandic yogurt, Skyr, which is strained 4 times and hence the thickest of yogurt types and highest in protein.

• drinkable

  • production characteristic: like stirred yogurt but broken into a liquid before cooled or repasteurized

• extra creamy

  • production characteristic: yogurt with higher cream content and often produced with stabilizers

• frozen

  • frozen yogurt is actually mostly milk solids with typically 10-15% yogurt

  • production characteristic: not just yogurt that is frozen because yogurt does not maintain the air bubble structure, yogurt to be frozen needs more sugars and stabilizers

• whipped

  • production characteristic: higher sugars and stabilizers required to maintain air bubble structure from the air whipped in

Yogurt vs. Sour cream vs. Crème fraîche vs. fromage frais

Making yogurt and sour cream uses the same industrial equipment (see the Handbook of Food and Beverage Fermentation Technology).

Differences among them are fat content (sour cream: ~20%, crème fraîche: ~30%, yogurt ~3.5%-12%), fermentation type, and level of acidity. Crème fraîche was originally unpasteurized cream that naturally thickens at room temperature. In the US, it is made with pasteurized cream so cultures are added to help it thicken.

Regional differences

France

Finding tangy yogurt in France is a quest, given the

Germany

With the sizeable Turkish community in Germany, it is not at all difficult to find great yogurt in my books!

My taste testing

What makes great yogurt for eating for me is its tang, unadulterated not-starchy consistency (no stabilizers or thickeners), and not too cream. I prefer yogurt that separates with time than taste or feel the texture of any of the stabilizers (e.g. starch, guar gum, xanthan gum, gelatin, carrageenan, maltodextrin).