I start with a pot and 1L of milk (usually one bag of whole milk), and most of the time I add some milk powder (1/4 cup or more, optional), which results in firmer yogurt. Whisk thoroughly, then heat:
Heat that up to 180ºF and either let it start cooling immediately or hold it at that temperature for a little while, say twenty minutes. Some recipes seem to feel this helps convert the milk proteins to make them suitable for yogurt, although I don't find it makes a huge difference.
Let it cool down to 115ºF. Take a ladle-full out, mix in one of these:
- a package of yogurt bacterial culture
- a few tablespoons of commercial yogurt with active culture
- a few tablespoons of your previous batch of homemade yogurt
I usually start with the bacterial culture, do three or four batches in a row using one batch of yogurt to start the next, and then go back to the commercial culture. Some recipes recommend that you avoid using your own culture too many times in a row in case you end up accidentally culturing something else along the way, something that you don't want to be eating in quantity. I'm not convinced that's totally necessary, but commercial cultures aren't terribly expensive, so I don't mind going this route.
Whisk the mixture thoroughly, then return it to the pot and whisk the mixture into the milk thoroughly, then distribute into jars:
This is a reasonable time to add a little sugar, honey, maple, vanilla, if you like. Don't go overboard, you can always add more sweetener later if you like. Put the jars in the dehydrator at 115ºF for four hours to let the culture do its work:
Check on them, if they don't seem firm enough, or you decide you want a very tangy yogurt, you can let it sit another couple of hours in the dehydrator. It won't be at its firmest yet, and there may be some whey at the top. That's ok:
Cap and chill the cans in the fridge, for a while, perhaps overnight. It'll firm up further, as well as cool down:
At this point it's at it's firmest, and is "set" yogurt. If you want to mix in some additional sweetener here you can. If there's whey, you can pour it off or stir it in. If you mix it at this stage it becomes "stirred" yogurt, which many people prefer:
If you want, you can put your yogurt in a cheesecloth or coffee filter overnight to drain some of the whey out, at which point it will become Greek-style yogurt.
Finally, eat, or feed to your children: