So I made yogurt for the second time today, and I'm sad that it didn't work out. The first time I used a quart of whole, regular (non-organic) milk from Wegmans because I couldn't find organic in that size. This time I used Homestead Creamery milk from Whole Foods. I bought it because it comes in a glass bottle which really appealed to me. Even though the milk is labeled "pasteurized" (vs. "ultra-pasteurized"), I found through subsequent research that they heat their milk to higher than required temperatures (170 deg vs 145 deg). I'm thinking that's why my yogurt didn't turn out this time. It makes me mad because it was a waste of expensive milk. Anyways, I will try again in a few weeks with a different brand.
The first time I made this, I didn't plan properly, and I let the yogurt sit for 12.5 hours (instead of 8). It turned out fine. I saved about 1/4 c from my first batch and froze it to use in my next batch. I read here that freezing does not destroy the cultures.
Here's a way to make yogurt without the crockpot. I think I'll give it a try next time. This crockpot recipe turned out great the first time, but I haven't been able to replicate that success for some reason.
1 qt (4 c) milk (not ultra-pasteurized!)
2-3 T plain yogurt with live active cultures
1) Put milk in the crockpot and heat on low for 2.5 hours.
2) Turn crockpot off, wrap the crockpot in a few towels and let sit for 3 hours.
3) Ladle 1-2 scoops of milk from the crockpot into a bowl and whisk in the yogurt.
4) Stir the mixture back into the milk in the crockpot.
5) Wrap the crockpot in towels and let sit for 8 hours.
6) For greek-style yogurt, strain the finished yogurt through cheese cloth.