Our family loves yogurt -- we eat it everyday for lunch, we mix it into our homemade North Woods Dressing, sometimes I even bake with it. We go through six to eight quarts of yogurt a week! This would be a huge dent into my weekly food budget. I didn't want to have to ration yogurt since it is such a great healthy food, so I did some reading and some experimenting and learned how to make my own homemade yogurt -- WITH NO SPECIAL EQUIPMENT! This process takes a while (about 24 hours) but very little of it is hands-on time, most is just wait time, so once you get the hang of it it becomes almost second nature. I do it weekly with two little ones running around.
This method is loosely adapted from Katie's method that she shares at Kitchen Stewardship, but I'm not nearly as detail oriented as she is, and I culture my yogurt in a different spot.
Here is your motivation to try this:
1 quart of Dannon all natural plain yogurt = $3 x 6 quarts a week = $18/week for yogurt
1 1/2 gallons whole milk = $4.50 + 6 x $0.0625 (starter) = $4.88/week for yogurt
I think I'll take the $13/week savings!
Quart sized canning jars (wide mouth are easier to wash)
Lids for the jars (used canning ones work, I prefer the plastic lids)
Medium or large stock pot (depending on how much yogurt you want to make)
Oven with a light
Candy thermometer (helpful but not necessary)
Note About Supplies: I use regular pasteurized, homogenized whole milk that is from hormone free cows. I can get this milk at the local gas station for $6 for two gallons. I'd love to be only buying raw milk but for $6-$8 per gallon around here, it just isn't in my budget. Besides, once the milk is heated it isn't raw anymore! For my culture I buy Dannon all natural plain yogurt. I can get it from my local grocery store and the only ingredients are "grade A cultured milk". I buy a quart and freeze it in two ice cube trays (48 cubes), then use one cube per quart when I make yogurt. You can use your current yogurt to culture the next batch but it will eventually stop working -- I found that in three to four cycles my yogurt starts to get "runny".
Fill the quart-sized jars with milk; leave about one inch head space.
Place a clean dish rag in the bottom of your stock pot (this helps prevent the jars from breaking when you heat them).
Place your jars in your stock pot and fill your stock pot with tap water until about three-fourths of the way up your jars.
Step 2:Heat the stock pot filled with water and the jars of milk over medium to medium high heat until the milk reached 175-180 degrees. Be careful not to heat the water up too fast (high heat) -- the jars will break! Use your candy thermometer or just watch for small bubbles around the edges and a "skin" to form on the top of the milk. The reason you are heating the milk is to kill any unwanted bacteria that has contaminated your milk and to "break apart" the milk proteins so the yogurt will be "store-bought" yogurt consistency and not "runny" or "string-y". This takes about a half hour on my stove but you don't have to watch it closely, even if you forget about it and the milk ends up boiling, it still works! (I've done this!)
Step 3:Once the milk has reached 175-180 degrees, turn of the heat and CAREFULLY remove the jars from the stock pot. I use oven mitts with rubber grips on them.
Allow the milk to cool until it reaches 110 degrees. You can speed this process up a bit by placing the jars in cold water -- be careful because a drastic temperature change will cause the jars to break! I just let them sit on my counter until they cool. This takes about an hour at my house.
Place a cube (or tablespoonful) or starter into each jar. Stir gently. Place lids on the jars and close until just finger tight.
Step 6:Place the jars back into the stock pot, still filled with water (it should still be warm). Cover the pot, or not, I do both, and place the whole thing into your oven with the light on. I've never actually measured the temperature of my oven during this stage but it stays warm enough to keep the water warm and the yogurt cultures well. You want the milk to be around 100-110 degrees to culture well. You can let your yogurt culture for 8-24 hours. I usually try to get it ready in the morning, put it in the oven around noon and leave it until the next morning. Some people say that the yogurt will get more "sour" the longer it cultures, I have not noticed a difference. I've also read that the longer you leave it to culture, the more lactose is "used up" so that it is tolerated better by those who are lactose intolerant.
Remove your stock pot from the oven and your jars of yogurt from the stock pot. Place the yogurt in the fridge. It will continue to thicken as it cools.