I started with skim milk that I got at BJ’s for $2.60 per gallon. I got out the crock pot, and it would comfortably hold 3 quarts (3 liters). After I poured in the milk, I turned the crock pot on high and left it alone.
Four hours later the milk was at 195 degrees F (90 degrees C). There wasn’t any scorching on the bottom or film on the top and I had not stirred it one bit.
I took the pot off the base, stuck it in the sink and filled the sink with ice water. I was going out with friends, so I went and took a shower and got dressed. When I got done the milk was at 100 degrees F (38 C). I took a cup of store-bought yogurt with active cultures, mixed it with a cup of milk from the pot to dilute it and poured the active cultures into the pot. With the lid on the pot, I put it in a warm (120 degree F) oven with the light on and turned the oven off.
The next morning I had yogurt. The whey had separated off nicely as you can see in this photo:
The whey is the clearish liquid. The white mass underneath the whey is the yogurt.
In the next photo you can see that I was able to separate nearly a quart of whey using a spoon. No straining was required at all to get this much whey out:
But I wanted to go all the way. I couldn’t find any cheesecloth. I thought about using a clean T-shirt, but ended up instead using a paper towel (a paper coffee filter would have probably been better) placed in the colander. I only let it sit for 10 minutes, and by then it was like sour cream, maybe even a little thicker.
And wow was it yogurty – very tangy. Leigh and I ate it plain, she ate it with fruit, I made Tandoori chicken with it, the kids ate it with chocolate chips, and so on.
The 3 quarts of milk cost about $2. The yogurt I used as the starter culture cost about $1 (but if I make it again I could use my yogurt as the starter). It yielded about a quart of whey and two quarts of yogurt. So the stuff I made was $1.50 per quart for non-fat Greek yogurt. And you can see how incredibly easy it was to make. It blows the store-bought price away.