Timeframe: 8 to 24 hours
Yogurt uses a thermophilic bacteria culture that needs a warm environment to come to life.
- 1 half pint active kefir or active yogurt culture
- 1 gallon whole milk
- mason jars
- silicone spatula or wooden spoon
- 1 gallon pot or double boiler
- optional: infrared thermometer or candy thermometer
- Preheat the oven on warm (170°F) and place the starter culture out to acclimate to room temperature; turn off oven once it preheats.
- Heat the milk till bubbles begin to form (180°F with thermometer). Stir frequently. Heating in a double boiler prevents scalding on the bottom of the pot.
- Cool milk to 110°F, or the point where it feels hot, but it is not hard to keep your (clean!) finger in it. You can speed the cooling by placing the pot of milk in a larger pot of cold water.
- Mix about 4 tbsp warm milk with 4 tbsp starter culture into each jar. Estimating is fine.
- Fill jars with remaining milk, cap loosely with metal lids, and place in oven.
- Check the yogurt after 8 hours. If it hasn’t thickened, preheat oven briefly till warmth is restored. It’s important not to cook the yogurt, the culture cannot survive beyond 130°F! Leave it another 4-8 hours.
- Refrigerate and enjoy. Reserve a half pint for use as the next starter culture.
Follow steps for Kefir Cheese.
Boiling milk causes its proteins to coagulate (imagine a ball of tangled yarn), which gives yogurt its thick consistency.
If you prefer yogurt in a more fluid form, simply use 110°F as the top temperature when heating the milk.
How to Clean Milk Scalded to a Pot
If scalded residue adheres to your pot after heating milk for yogurt, try one of these easy techniques for cleaning.
- Pour equal parts vinegar and water to cover the bottom surface of the pot and let rest overnight, then scrub clean with a sponge.
- Or, bring a small amount of water to a boil and add baking soda. Turn the heat down and let boil for several minutes, ensuring the bubbles don't overflow. Drain, rinse, and scrub clean with a sponge.