blog post I was tempted to try making some ourselves.
I started out heating up the milk to 180 degrees. I think this is to kill off any bad bacteria before you grow all the good bacteria.
The instructions called for letting it cool down to 115 degrees. I figured I had some time so I walked the dogs, threw in a load of laundry, and mixed up some corn bread muffins and got them baking.
Once the thermometer reached 115 I mixed in the starter yogurt the instructions called for (three tablespoons of plain yogurt with live cultures in it) and filled up my mason jars. NOTE: the results were uneven, some jars were pure yogurt and others were more like drinkable yogurt. In my next batch I added more starter yogurt (half a pint's worth) and whipped it around the pot with my immersion blender for even distribution. This worked much better.
I filled up a Styrofoam cooler with 115 degree water and loaded them in.
I wrapped the cooler with two towels and left it alone (the second time, the first time I kept opening it up and checking to see if it was still warm/anything was happening - this may have contributed to the runny result). I checked it once after four hours and it was down to 109 degrees. I added some scalding water to bring the temp up a bit (mixing it around quickly so as to not to kill the bacteria we were trying to grow).
I checked it after 8 hours and it was like magic! What was once milk is now yogurt:
I immediately saved some for the next batch (hid it in the back of the fridge). One more step for Greek yogurt though. I lined a colander with cheese cloth and put it over a pyrex measuring cup. I stuck it in the fridge over night. In the morning there was Greek yogurt left in the colander and whey in the pyrex (I put three quarts of regular yogurt and got about 1.5 quarts for a 50% loss rate). I saved the whey for treats for the paws (they all love it).
We've been sweetening it with strawberry syrup I canned last summer, honey or maple syrup. I can see lots of variety coming our way: honey, maple, strawberry, blueberry, even mulberry. The possibilities are limited only by our dwindling supply of home canned preserves.