Recipe: Greek-Style Yogurt
From The America's Test Kitchen DIY Cookbook
Friday, March 22, 2013
Makes 2 cups
Make today, enjoy tomorrow
4 cups 2 percent pasteurized (not ultra-pasteurized or UHT) low-fat milk
1/4 cup nonfat dry milk powder
1/4 cup plain 2 percent Greek yogurt
1. Adjust oven rack to middle position. Place fine-mesh strainer over large glass bowl, then set bowl in larger bowl filled with ice water. Heat milk in large saucepan over medium-low heat (do not stir while heating), until milk registers 185 degrees. Remove pot from heat, gently stir in milk powder, and let cool to 160 degrees, 7 to 10 minutes. Strain milk through prepared strainer and let cool, gently stirring occasionally, until milk registers 110 to 112 degrees; remove from ice bath.
2. In small bowl, gently stir 1/2 cup warm milk into yogurt until smooth. Stir yogurt mixture back into milk. Cover tightly with plastic wrap and poke several holes in plastic. Place bowl in oven and turn on oven light, creating a warm environment of 100 to 110 degrees. Let yogurt sit undisturbed until thickened and set, 5 to 7 hours. Transfer to refrigerator until completely chilled, about 3 hours.
3. Set clean fine-mesh strainer over large measuring cup and line with double layer of coffee filters. Transfer yogurt to prepared strainer, cover with plastic, and refrigerate until about 2 cups of liquid have drained into measuring cup, 7 to 8 hours. Transfer strained yogurt to jar with tight fitting lid, discarding drained liquid. Yogurt can be refrigerated for up to 1 week.
To Make Lactose-Free Greek-Style Yogurt: Dry milk powder helps thicken this yogurt, but it contains so much lactose the cultures can’t consume it all. Omit the dry milk powder for a lactose-free version. The draining step may take as few as 4 to 5 hours.
Why this recipe works: My devotion to all forms of dairy began at an early age, a given since I grew up in Vermont. Today, making yogurt is a favorite ritual for me. There are good reasons to make your own. It’s easy, and quality pints don’t run cheap. But perhaps most important, many brands take shortcuts, like using gelatin, pectin, or inulin (a flavorless dietary fiber) to make a thicker product, which saves money and time but degrades flavor. Instead of worrying about additives, off-textures, or sour flavors, just make your own. Use the best-quality homogenized, pasteurized milk and “starter” yogurt (with live active cultures) that you can find.
—Jennifer Lalime, Test Cook, Books
Pour it in, heat it up: I always start with the best-quality milk I can find. I use low-fat milk, but you can use whole or skim. Heat the milk in a saucepan to 185 degrees. Resist the urge to stir since stirring will lead to small lumps in the final yogurt. At 185, the milk's proteins reconfigure and create a creamy, viscous texture once cultured (which will happen in a few steps), rather than separating into curds and whey. Off the heat, gently stir in dry milk powder, which will help thicken the yogurt. I find that the yogurt sets more reliably if I let the milk cool for about 10 minutes, or until it reaches 160 degrees.
Quick cool: Once the milk has cooled to 160, you can speed up the process a bit. The milk needs to be between 110 and 112 degrees to create a friendly environment for the culture and to prevent curdling. To reach this temperature quickly, strain the mixture into a bowl set over an ice bath. Not many yogurt recipes call for straining, but I find it wise since it removes any stray lumps from the bottom of the pot or clumps of dry milk that didn't dissolve. When the milk is cooled to about 112 degrees, it will feel warm, but not hot, to the touch (similar to water when proofing yeast).
Get your starter: Making yogurt from milk requires adding a starter with live cultures. Freeze-dried starters such as Yógourmet work, but the flavor is too tangy for me. I buy a small container of yogurt (make sure it contains live active cultures) as a starter. To make it easier to incorporate, I thin it first by stirring a little of the cooled milk into the yogurt until smooth. Then add the starter to the bowl with the milk and stir to combine. Cover the bowl with plastic wrap and pierce several holes in the top to allow the yogurt to breathe.
Find a warm place: The bacteria prosper around 100 to 110 degrees. Any lower and the culturing will take days; any higher and the milk will curdle. I tested keeping the bowl in the oven with the light on, or, if your oven goes low enough, set it to 100 degrees. It will take five to seven hours to transform into yogurt; start checking it at the five-hour mark. (Yogurt doesn't like to be disturbed, so try not to jiggle the bowl too much.) When it's ready, the yogurt will appear thickened, creamy, and set. Sometimes there is a little liquid in the bowl. It's simply separated whey, which you can stir back in.
Go Greek: Since I like a thicker texture and richer flavor, I strain my yogurt to mimic Greek-style. But first, let it cool completely in the fridge (it will firm up a bit). Then set a fine-mesh strainer over a large liquid measuring cup or bowl and line it with a couple of coffee filters or a double layer of cheesecloth. After pouring the yogurt into the strainer, cover it with plastic wrap and refrigerate until 2 cups of whey drain from the yogurt, which will take seven to eight hours. For thinner yogurt shorten the time or just skip draining altogether.
Breakfast is served: After the seven or eight hours of straining, you'll have about 2 cups of delightfully rich and creamy yogurt. (If you used skim milk and nonfat yogurt, your final yogurt will be a little bit thinner but you can always drain it longer.) Honey is my go-to sweetener for yogurt, with raw sugar coming in a close second. Top the yogurt with a handful of fresh berries, and I'm ready to start my day.