For your yogurt culture, you can use either store-bought plain yogurt with active cultures, a freeze-dried heirloom starter, or yogurt from a previous batch of homemade yogurt.
If you are using freeze-dried heirloom starter for the first time, read the directions that came with it. Instead of adding 2 tablespoons of yogurt, you’ll add the entire packet of freeze-dried starter in step 3.
Smell your gasket before you begin. If it carries a strong aroma of chili or curried lamb, you may want to order an extra gasket, as the yogurt can absorb those smells. Reserve the neutral gasket for making yogurt or other delicate foods.
- 1/2 gallon pasteurized milk (we like organic whole cow’s milk)
- 2 tablespoons yogurt culture (see Recipe Notes)
1 Boil the milk in the Instant Pot: Pour the milk into the Instant Pot’s insert. Lock on the lid. It does not matter if the steam vent is open or closed. Press the “Yogurt” button, then press “Adjust” so the digital readout says “Boil.”
After this, on some Instant Pot models, you'll need to press the "start" button. Eventually it will bring the milk to 180° F (this kills off undesirable microorganisms). It usually takes about 30 minutes.
When it's done, the Instant Pot will beep and its readout will say “Yogt.”
Optional: For thicker yogurt, keep the lid on, press YOGURT, then press ADJUST so the digital readout again says “boil.” Start a timer for 5 minutes; once the time is up, proceed with the recipe below. This cooks the milk a little longer and leads to thicker yogurt.
2 Cool the milk: Right after the Instant Pot beeps, turn it off and lift out the insert of hot milk. Put the thermometer in the milk and wait until it’s 116° F. This can take as long as an hour.
To speed down the cooling, set the insert of hot milk in a bath of ice water and stir the milk; the temperature will drop in about 5 minutes. (If it dips below 110°F, pop the insert back in the cooker, press “Yogurt,” then “Adjust” and monitor the thermometer until it’s back in the right zone. Remove the insert from the cooker.)
Remove the thermometer. There will be a film of coagulated milk on the surface of the milk; carefully lift this off with a spoon and discard (this film won’t ruin your yogurt, but it creates a distracting texture once it’s finished).
3 Temper the starter: Put the starter in a medium bowl and add about 1/2 cup of the warm milk. Whisk until smooth, then pour into the insert of milk and whisk to combine.
4 Incubate the yogurt: Set the insert of milk back in the Instant Pot, lock on the lid (once again, the steam vent may be open or closed), and press YOGURT. If the readout does not say “8:00,” add time using the + button until it does.
The Instant Pot will incubate your yogurt for 8 hours before switching itself off (the display will read “Yogt” once the 8-hour default programming is complete). You can use the +/- button to adjust the incubation time.
Note that, when incubating yogurt, the timer counts up (when pressure cooking with your Instant Pot, the readout counts down). So, when readout says “2:45,” it’s been incubating for 2 hours and 45 minutes.
5 Check your yogurt: Start checking on your yogurt after 4 hours. As the yogurt incubates, you don’t want to jostle the Instant Pot too much—it can keep the yogurt from setting well.
It can take anywhere from under 4 to over 12 hours for your yogurt to set. A lot of it has to do with how active the cultures in your starter are—fresher starter takes a lot less time to incubate. Be patient and don’t lose hope!
Open the lid carefully when you peek; a lot of condensation forms around the gasket and you want to minimize it dripping back onto the yogurt.
The yogurt is set when it jiggles all as one unit if you carefully nudge the insert, and it does not run if you tip the pot a bit. You may see some clear liquid (the whey) floating on the surface and at the edges.
6 Cool the yogurt to room temperature without stirring: Once your yogurt is set, gently lift the insert from the cooker. Pouring it out or stirring at this point can make your yogurt runny, which you don’t want. You can set the insert on a rack to help it cool faster, but don’t pop it right in the fridge, since rapid temperature changes can also thin your yogurt. Once it’s at room temp (about 2 hours), set it in the refrigerator.
7 Chill at least 6 hours. The yogurt might seem lumpy after it's been chilled, but a vigorous whisking will smooth it out. At this point, you may strain it or transfer it to sterile containers (I like quart glass jars).
8 Store the yogurt: The yogurt should be good for up to two weeks. As it sits in your refrigerator, it will get tangier and lose some of its body.
Bonus: How to make yogurt in heatproof jars
To make yogurt in heatproof jars (of any size), put 1 cup of water in the insert and set the steam rack on top. Fill the jars with milk, stopping 1/2 inch from the rim. Set them in on the rack; lock on the lid. Press the “Steam” button and use the “-/+” keys to adjust the time to 1 minute. When the cooker beeps, let the pressure release naturally.
Open the cooker and use canning jar lifters to remove the jars. Stick a thermometer in one and wait for the milk to cool to 116° F. This can take up to an hour. Remove and discard any skin from the top of the milk in the jars.
Divide the appropriate amount of starter among the jars—it’ll depend on how much the jars hold. Return the jars to the cooker, lock on the lid, press the “Yogurt” button, and proceed with Step 4.