I mentioned that I make my own yogurt last week and people seemed really keen on learning how to do so themselves! I took pictures while I was doing it this last week so I could put together a quick tutorial. I did this as an experiment to start, but it does end up being a bit cheaper than storebought, creates less waste, and I genuinely think it tastes better as well.
1. Pour milk into a pot. This can be any type; I've heard it even works with non dairy milks, although I haven't tried it myself.
2. Heat the milk up until it gets over 180 degrees farenheit.
3. Take the milk off the heat. If you got absorbed in a book like me and didn't stir the milk whole you were heating it up, use a spoon to scrape out all the burnt milk bits. You're going to want to cool your milk down to the magic temperature of 115, but you need to start steps 4-6 when the thermometer hits around 125 so you have time before it cools down completely.
4. Put some "starter" yogurt into a bowl. This can also be any type of yogurt. I use both nonfat milk and yogurt and have never had a problem. You could theoretically do this with just a tablespoon or two of starter, but I tend to glob a fair amount in just to be safe.
5. Ladle some of the warm milk into your starter bowl and mix until you have a nice milky yogurty mixture.
6. Pour the entire milky mix into the main pot and stir it in. You should be right around 115 or slightly above at this point. Time to move fast!
7. Cover the milk pot.
8. Fill your microwave or (fully cool) oven with a towel.
9. Place the pot in the towel and cover it completely to keep it at the magic temperature throughout the night.
That's it! In the morning I'll have yogurt. You can go ahead and eat it right then, but I generally strain out the liquid whey so I can have a thicker Greek yogurt, so it's more of a two day process for me.
10. To strain the yogurt, I pour it into a sieve over a bowl with coffee filters layered into it. If you have the large commercial size coffee filters, those would work too, but the small ones are so cheap and easy to find that I just use those instead. I've read that the yogurt is so acidic that you could leave it out on the counter to strain without it going bad, but I play on the safe side and keep it in the refrigerator.
11. I usually put this all together before work and separate it out later when I get home. I store the whey in a cleaned out plastic milk carton and I keep the yogurt in a mason jar to avoid any contamination. You can supposedly do a lot of things with the whey, such as make ricotta, but most of my experiments haven't really worked out. It's something I'm still working on.