Yogurt isn't difficult to make, but you do need something that will keep the culture at 115 degrees for 10 hours. I have an Instant Pot, which is a pressure cooker that happens to also have a yogurt setting, but Amazon sells yogurt makers as well.
What you need to make yogurt:
- A yogurt culture (you can use a few tablespoons of yogurt you already have, or buy one)
- Something to keep the milk at the right temperature
And that's it!
My Instant Pot also pasteurizes the milk by heating it to 180. I THINK some people make yogurt with raw milk, but I'm not sure. Since the milk cultures at a temperature in the *danger zone* that pathogenic bacteria like and grow well in as well, it's pretty important to kill off any bad bacteria before you make yogurt. Not only will they become more dangerous since they'll proliferate in the warmth, but they will also compete with the good bacteria that you want to be populating your culture, so I don't think your yogurt will come out too well if you don't kill the bad bacteria first.
I start with 2 quarts of milk. That makes about a quart of strained yogurt, which lasts a week or so for a family of 4 eating it almost every day. I dump the milk into the Instant Pot, put the lid on, press "yogurt," then "adjust" to set it to boil the milk, and it starts automatically. When this step is done, the Instant Pot will beep.
After the milk is boiled, I put it in an ice bath to cool it quickly down to 115 degrees, which is the temperature you want for the milk to culture.
I set a probe thermometer in it so I can monitor the temperature, and stir it to get it to cool faster. This process happens pretty fast, so have your yogurt culture ready before you start.
Once it cools down to 115, I dump in a few spoonfuls of yogurt and whisk it in.
When I was researching how to make yogurt, the websites I read suggested putting the yogurt in a bowl and ladling in a scoop of warm milk, then mixing that into the bigger pot. I'm not sure why they do this step. I've done it that way and just putting yogurt straight into the pot once it reaches 115 degrees, and I haven't noticed a difference at all.
After you mix in the yogurt, dry off the pot (since it's wet from the water bath), and put it back into the Instant Pot machine.
The Instant Pot automatically starts at 8 hours for yogurt. I've done 8, 9, and 10 hours. The longer you let the culture set, the more sour/tart it will be. I like a more tart yogurt, so I usually let it go 9 hours. For the instant pot, you just press the "+" button two times until it gets to 9:00. After a few seconds, it starts automatically.
When the yogurt cycle finishes, it will read "YoGrt" on the display.
At this point, you can pour it into a container for regular yogurt, or strain it for Greek yogurt. I prefer thicker yogurt, so I strain it overnight. I pour the yogurt into a colander lined with a double layer of cheesecloth, set it in a bowl, cover it with a plate, and let it sit overnight to strain. In the morning, I transfer the strained yogurt into a container and add a little of the whey back in, since straining it that long makes it VERY thick and it's a little hard to stir into things at that thickness. Adding a spoonful or two of the whey back makes it a nice consistency for eating with granola or in smoothies.
And that's it! There are a lot of variations to making yogurt, such as culturing for less or more time. I'll have to try a few different things to perfect it, but so far, it's really good!