The recipe calls for whole milk, but you can use skim or 2%. It is a good idea to start with whole when you are learning because it will set a bit better. Once you got the process down, you can try lower fat milks. This recipe should be started in the early evening (5-6 PM) or done on a weekend because of the timing.
1/2 gallon of whole milk, pasteurized (NOT ultra-pasteurized)
yogurt starter (I used 7 oz of Fage, but next time I will use my homemade yogurt)
1) Pour the milk into a very clean crock pot. Set to low and leave for 2 1/2 hours so the milk reaches 180 degrees. Most crock pots will bring the milk close to this temperature, but you might want to use a thermometer to check. If is not at 180, leave it for 15-30 minutes. If it nowhere close to 180, turn the crock pot up to high and check in 30 minutes.
Why: By bringing the milk up to 180 degrees you kill the bad bacteria that you do not want in your yogurt that can effect the taste and the texture of the final product.
2) When the milk is at 180 degrees, unplug the crock pot, leave it covered and come back in three hours. At this point it should be at about 120 degrees. If not, let it cool more.
Why: By letting the milk cool to 120 degrees, you bring the milk to a temperature where the live cultures can thrive and do their "thing" that turns the milk into yogurt. If it is too high, the live cultures will die. If it is too cool, the cultures will not turn the milk into yogurt.
3) Scoop out a couple cups of milk and whisk the starter yogurt in and pour back into the crock pot. Wrap the crock pot in a towel and let it sit for at least 8 hours. I put my crock pot wrapped in towel in my oven (turned off). If you are doing this in the early evening after this step you can go to sleep.
Why: You want the milk to stay in a temperature range where the live cultures can do their thing. The longer your milk stays in this range, the better the yogurt will taste. This is why I put it in my oven. I figured if any heat escaped, at least it would be in a small enclosed space.
4) After 8 hours (and even a bit longer if you want tangier flavor), you should have yogurt. It might be a bit runnier than you are used to (store bought yogurt typically contains thickeners), but you can strain it in cheese cloth or with coffee filters. The more you strain it, the thicker it will be.
5) Add whatever sweetener you want--sugar, vanilla, honey, fresh fruit, or frozen fruit.
Enjoy! It should last 7-10 days in the fridge. I store it in Mason jars. Making your own yogurt will save you a lot of money. I typically by Chobani singles which are $1.35 each. The yogurt I made today cost under $3.00 and I got at least 48 ounces. Next time it will cost less since I can use my own yogurt as a starter. You also avoid all of the weird things in store bought yogurt and you can control how much sugar or sweetener is in it.
The Straining Process