How to make non-fat Greek yogurt in an instapot
This recipe is handy for Pesach, when you don’t want to have to use the typical kosher l’pesach yogurt full of guar gum, pectin, modified food starch and other low quality ingredients. You can make this directly in the metal instapot lining pot, or you can choose to use containers placed inside the instapot lining on a rack. I have come to prefer the latter. I use quart mason jars, and can get 3 into a pot at once on the rack and still close the lid. I know this looks like a wall of text, but it really takes more effort to explain than to do.
Ingredients
- 2 quarts nonfat milk
- 3 tablespoons of commercial yogurt to use as starter
- A note on starter: You can generally “backslop” only once or twice before the yogurt bacteria weaken. By this I mean that if you create a batch of yogurt, you can only use that yogurt as a starter for another batch once before the quality goes down. Commercially made yogurt bacteria strains are not designed to propagate themselves indefinitely. Beyond that, the yogurt may not set or taste off. There are dried heirloom starter cultures you can purchase online that are intended for indefinite use, but I do not have any experience on using those, so cannot advise. That said, I have read that if you like your yogurt sour, you want to source Bulgarian yogurt starters.
Method
I have rewritten this recipe to reflect the limitations of the instapot and how to get around them.
Here’s the ideal: You bring the milk up to 180° F (82° C) for ten minutes or so. This is not just because pasteurization helps keep you safe from things like listeria, tuberculosis and E. coli… the smoothness of the end result also depends on denaturing the milk proteins at this temperature, and it needs to be held at the temperature and no higher for optimal results. Then, the milk needs to cool to between 105° F - 115° F (42° C - 49° C) and held at that temperature with your starter culture mixed in for a good 10 - 24 hours which is the optimal temperature for growing your yogurt culture.
The problem: The instapot measures temperature by taking the temp of the bottom of the pot. This does not necessarily accurately reflect the temperature of liquids inside, especially if there is protein in the liquid that might burn. It is easy to under-do the denaturation process at 180° F (82° C), and it is also easy to scald the milk accidentally. There are a few ways to counteract these problems.
First method: using the instapot for everything. It is far less likely that you will burn the bottom of the milk if the milk is placed inside mason jars resting on the wire rack that came with the instapot. I find that I can get as many as three separate one quart mason jars into my instapot resting on the rack. Doing it this way requires that you pour water into the instapot such that it comes up at least an inch or so above the bottom of the mason jars, otherwise, there is nothing to heat the liquid in the jars. You are essentially using the instapot like a double boiler. You will need to monitor the temperature, and honestly, it’s just easier to put the whole thing on sauté setting for awhile and let that water boil, stirring the milk in the jars on occasion to even out the temperature. Make certain the water level does not get too low. Using the instapot in this way means that you are very unlikely to scald the milk… I find that I can’t get the temp much above 180°F (82° C) at all. After it hits 180° F (82° C) set a timer for 10 minutes and turn off the heat afterwards. It’s a good idea to make sure you’re maintaining temperature. Let the temperature in the jar(s) cool to the target temperature range (105° F - 115° F or 42° C - 49° C), remove a few spoonfuls of the milk to a separate container and stir your starter into this until it is consistent and loose, and then parcel out that mixture into the jar(s). Set the instapot on the yogurt setting for a minimum of 10 hours and a max of 24 and let the jar(s) do their thing with the lid on the instapot. Chill and strain if you wish the yogurt to be thicker.
Second method: stovetop/instapot combo. This method takes less prep time, and allows you to make the yogurt directly in the instapot. I think if you are looking to make a really large quantity, this is the way to go. You are going to let the stovetop do what it’s good at (heating liquids quickly), and the instapot do what it’s good at (maintaining a low temperature over time), and you are not constrained by the volume of jars you can get into the pot.
Put the milk in a pot on the stove, and heat to 180° F (82° C), stirring often to make sure that the bottom does not scorch. Maintain 180° F (82° C) for 10 minutes, and pull off the heat. Pour the heated milk into the instapot… either directly or you can do the jars-on-the-rack approach, as well. Wait until the milk has hit the target temperature range (105° F - 115° F or 42° C - 49° C), remove a few spoonfuls of the milk to a separate container until it is consistent and loose, and stir your starter into this, and then stir that mixture into the rest of the milk in the instapot. Set the instapot on the yogurt setting for a minimum of 10 hours and a max of 24 and let the jar(s) do their thing with the lid on the instapot.
Chill.
The difference between European style and Greek style yogurt is that Greek yogurt has the whey strained out of it. I use a dedicated fine nylon mesh strainer for this purpose, but supposedly you can use 3 - 4 layers of cheesecloth to do this as well. I find that 3 - 4 hours of straining in the refrigerator is ample to produce a very thick yogurt. The whey can be used to add protein content to soups and stews, but it will impart a tart flavor.
I don’t need to make gallons at a time, so for me the all-instapot quart jar method works very well, is a little more fail-safe, and has less clean up.
Keep refrigerated, and use within ten days.