I pour milk into a pot and put the pot into another pot, a bigger pot, a pot full of water. I boil the water. This double-boils the milk.
While I’m waiting, I add some powdered milk to the milk to give it more body. If I’m using a quart of milk, I use enough powdered milk to make another quart of milk. That way I have double-milk yogurt when I’m done.
After the water gets a good boil going, I take the pot of hot double-milk, and place it in my sink, which is nearly full of cold water. I stir the double-milk till the steam stops rising. Then I grab my trusty little thermometer and check the temp.
Somewhere around 110′ F is good. Once that is reached, I take the pot out of the water. I add a couple of heaping spoons of yogurt to the milk and stir. Then I pour the whole mess into my yogurt maker and wait about 6 hours.
Some people just wrap the pot of inoculated milk with a heating pad to keep it warm. Some folks slide the thing into the oven and leave the light on for it. Yogurt is created by a couple of different bacteria. One likes to live around 111′ F, the other around 114′ F. I don’t trust a heating pad or my oven to maintain the right temperature. I live in a drafty world. You want to keep the little yogurt fellers happy after all, or they won’t do their job to keep you happy.
Once upon the time I used a yogurt maker that came with several different ceramic cups with plastic lids. I topped them each up with inoculated double-milk, and put them in their little warming coves of the yogurt maker. The cups were handy, if brittle. Just the right size for one serving. But somehow it wasn’t as handy as bulk yogs. So I use this Yogourmet Electric Yogurt Maker. In fact I’ve got 2 of them so I can make a gallon and 1/4 at a time.
The first time, you get your yogurt starter from some store-bought yogurt. I tend to stay away from Dannon or other national brands and look for something more local. But if it says “active cultures” that should pretty much guarantee that it’ll work for you. After that first time, you save back a little of your own yogurt to make the next batch.
Some folks say that over time their yogurt gets too sour, so they get fresh starter frequently. I only go to the store for fresh starter when I’ve made a bad mistake. For instance, do NOT try using buttermilk to make the yogurt. Originally buttermilk was made the same way yogurt is. Nowadays it’s more likely that they just add some kind of acid to regular milk, and some thickeners. Anyway, the acidity keeps the yogurt cultures from growing. You end up with warm buttermilk. Mmmm. Hey, let’s go buy some new yogurt starter!
One time I was in the middle of vacuuming by the time the water started to boil. Being busy and indisposed and all, I let the boiling go on for a long time. The yogs came out interesting: like marshmallow creme without the sticky. Or like in John Carpenter’s The Thing, when they stick the hot poker into the sample of blood. Kinda creepy. Hey, let’s go buy some new yogurt starter!
You get the idea.
This is where the freeze-dried fruit comes in handy. Just stir some into the yogurt, give it a minute to re-hydrate, and you’ve got fruit flavored sour stuff!