I've heard rumblings of interest lately in the process of making yogurt at home, and as it is actually a fairly easy and economical and delicious endeavor, I thought I'd type up my recipe and throw it out there for whoever wants to give it a try. I make my yogurt in quart jars, and often make and incubate two or three quarts together at a time, which lasts our family about a week. We eat a lot of yogurt, with granola or fruit for breakfast, and with Indian food, and as an alternative to sour cream or mayonnaise in other recipes. You can drain the finished yogurt in cheesecloth for a few hours to get Greek yogurt, or for several hours to make home-made cream cheese. I'm pretty sure that the recipe is scalable, and also open to tweaking, so be fearless and experiment! If your yogurt doesn't set the first time you try, don't fret and don't throw it out, you can use it for baking (coffee cake, muffins) just fine. And always save a few tablespoonfuls of your last batch to use as starter for your next.
YOGURT:
makes 1 quart
Materials:
4C Pyrex glass measuring cup
An accurate thermometer - and if you have a digital one with alerts then you don't have to babysit the cooling process!
Clean quart jar(s) - and it hasn't seemed to make a difference if they're sterilized or not
A clean plastic picnic cooler with a tight fitting lid, large enough to hold your jar(s)
Ingredients:
4 C milk - you really can use any type and any fat here! We use 2% milk from the grocery store; use whatever milk you would normally want to drink. Higher fat gives creamier yogurt, obviously.
1/4 C powdered milk - optional - some folks think it makes a slightly thicker yogurt and it does add protein.)
1 Tbsp. yogurt starter - if it is your first batch, make sure you buy commercial yogurt that contains 'live and active cultures.' I'm pretty sure that most brands do, but check the label to be sure!)
Method:
The most important thing with yogurt-making is temperature. The bacteria we want to put to work are only active at a specific range of temperatures, so make sure your thermometer is accurate!
Working one quart at a time, stir milk and powdered milk together in your glass measuring cup and microwave on high for ~6-9 minutes till milk reaches ~170-180 degrees. Ever microwave is different, so closely monitor this step till you know your own microwave oven. Alternately, heat milk in a saucepan on the stove top till it reaches ~170-180 degrees. Heating the milk is supposed to result in a smoother, more consistent yogurt.
Now take your hot milk and let it cool back down to 120 degrees. I do this by placing the measuring cup (or saucepan) in a cool water bath in my sink. If you have a digital thermometer, set it to alert when the temperature drops below 120 degrees; if you don't, check frequently so that the milk doesn't cool too much. The bacteria are only active between about 110-120 degrees.
While the milk is cooling, scoop 1 Tbsp. of your starter yogurt into your quart jar. Fill your cooler about a third full with 120 degree water (again, check your temperature carefully, and be prepared to adjust the water level once you get your jars in - they should be fully immersed, but their lids should not be under water) and put the cooler lid back on.
Once the milk has just dropped below 120 degrees, pour a little into the jar and stir it to mix in the yogurt starter. Then pour in the rest of the milk and give it a good stir. Screw your lid on tight and place the jar into the cooler to incubate, remembering to cover the cooler again so the water inside stays as close to 120 degrees as is possible.
Repeat method for additional quarts, placing each into the cooler as soon as they are jarred. Try not to jostle the jars that are already incubating, though!
After about 6-10 hours, overnight, or up to 18 hours or so, take the jars out of your cooler and place them in the fridge to cool and set. They should be fairly 'yogurty' at this point, but they will firm up a bit more as they cool. Once cooled you can drain the yogurt in cheese cloth to get a thicker product. (You can also mix in honey, jam, or other flavors or sweeteners. I've heard you can do this after incubating but before cooling, but I haven't tried it yet - plain yogurt is just so delicious already! So experiment!) Also, I've heard that the longer you incubate the yogurt the firmer and tarter it becomes, but I would suggest you let it go for at least 6 hours, if not more like 8, to make sure it sets up well. We've 'forgotten' our yogurt for up to 15-18 hours, and it was still very good, so I think there is room to experiment there, too.
Cool for a few hours to let the yogurt set, then enjoy!
Other links:
http://graham.main.nc.us/~bhammel/tscd/misc/yoghurt.html
http://en.wikipedia.org/wiki/Yogurt
And if you're really feeling adventurous:
http://thestonesoup.com/blog/2012/03/yoghurt/
