Yogurt

Why This Recipe Works

For tangy, creamy yogurt, we skipped the usual preliminary scalding and cooling steps by starting with ultra-pasteurized milk, which has already been rapidly heated and chilled. This lets bacterial cultures turn it into an especially thick and silky yogurt. We brought the milk to 115 degrees and stirred in store-bought yogurt with live cultures, strains of bacteria that digest the lactose in milk, producing lactic acid. This acid is what gives yogurt its flavor and causes the proteins in milk to gradually form a gel, turning liquid milk into creamy yogurt. To provide those bacteria with a cozy environment to do their work, we placed a covered pot of boiling water in the oven beside the pot of warm water holding the jars of milk. This setup helped the oven maintain a temperature of 100 to 115 degrees for hours. After that, it was just a matter of tasting for tartness and thickness to decide when to pop the jars into the fridge to let the yogurt set.

Ingredients

7½	cups whole, 2 percent low-fat, 1 percent low-fat, or skim milk
½	cup plain yogurt

My Sous Vide Directions

1. Scald the milk in a saucepan (bring to 181°F.) Remove from heat and allow to cool to 115°F.
2. While milk is cooling, prepare sous vide water bath, with 6 quarts of water in the container. Preheat to 110°F.
3. Whisk yogurt into warm milk until thoroughly mixed and distribute mixture evenly between 3 one liter Weck jars, ~3 cups in each container.
4. Place Weck jars into sous vide water bath and cover loosely with glass lids. Cover water bath to prevent evaporation. Let milk incubate for 7 hours. Using clean spoon, taste yogurt for tartness and consistency. If tarter, thicker yogurt is desired, return jars to water bath and incubate for up to 8 more hours.
5. Remove jars from water bath and refrigerate until fully cooled and set, about 8 hours. (Yogurt can be refrigerated for up to 2 weeks.)

Original Directions

1. Bring milk to 115 degrees in saucepan over medium heat, 2 to 5 minutes. (If your milk gets hotter than 115 degrees, let it cool to 115 degrees before proceeding. Higher temperatures can kill some cultures.) Off heat, whisk yogurt into milk until very well combined. Divide mixture evenly between two 1-quart Mason jars (they will be very full; a funnel can be helpful for this step). Add lids, then screw on rings until just finger-tight.
2. Adjust oven rack to lowest position and turn on oven light. Bring 5 quarts water to boil in large covered pot. Place jars in second large pot. Add water until jars are submerged to their necks. (If jars are taller than pot, add water to 1¼ inches from rim of pot.) Remove jars and bring water to 120 degrees over medium heat. Return jars to pot of 120-degree water. Transfer both pots to oven. Incubate yogurt, without opening oven door, for 5 hours.
3. Remove 1 jar from water bath. Using clean spoon, taste yogurt for tartness and consistency. If tarter, thicker yogurt is desired, return jar to water bath and shut oven door. (Bear in mind that yogurt will thicken significantly as it cools but can be loosened up by stirring prior to serving.) Set oven to 350 degrees and heat for 3 minutes (start your timer as soon as you set the dial; oven will not reach 350 degrees). Turn off oven and let incubate for up to 10 more hours, repeating heating step each time oven door is opened. Remove jars from water bath and refrigerate until fully cooled and set, about 8 hours. (Yogurt can be refrigerated for up to 2 weeks.)

How to Customize

Making yogurt that you’ll love begins with choosing a starter yogurt that you enjoy. Any variety (whole milk, Greek, Icelandic, etc.) will do the job, but keep in mind that different brands use different combinations of bacteria, and this accounts for variability in flavors ranging from buttery to cheesy to tangy to mild; textures can be firm, thin, gelatinous, ropy, or custardy. These qualities will transfer to your finished yogurt.

Then there’s the milk. Any type (whole, low-fat, or skim) will work, but the more fat your milk contains, the richer your yogurt will be and the more structure it will have.

And yet, the starter and milk are only the beginning. Here are more ways to create a truly artisanal yogurt to suit your personal tastes.

Tweak the Consistency

RICHER

Sustitute ½ cup ultrapasteurized heavy cream for ½ cup milk.

DENSER

Whisk ¼ cup nonfat dry milk powder into cold milk before heating it.

STRAINED (Greek yogurt)

Place triple layer of cheesecloth over mouth of jar, screw on lid ring, and drain in refrigerator upside down in 2-cup measuring cup overnight.

Add Flavorings

EXTRACTS

Stir ¼ teaspoon extract (we like vanilla or almond) into milk along with starter.

SWEETENERS

Garnish individual servings with white or brown sugar, honey, maple syrup, or fruit jam.

Control Sourness and Thickness

Adjust the incubation time to produce the effect you desire: The longer yogurt ferments, the more lactic acid is produced, and the more sour and thick it becomes. Chilling stops fermentation and allows the gel to set fully (it will loosen when stirred or served).

Source

Cook's Illustrated - March/April 2022