What you will need.
1. A crock pot that has "warm" setting and is large enough to fit your glass jar of yogurt that you will be culturing
2. A glass jar with lid. I use a 1/2 gallon mason jar. But if your making less yogurt you can use a smaller jar. Mason jars work well.
3. Fresh plain yogurt. I use Stoneyfield organic or my own less than a week old yogurt. 1/4-1/2 cup per 2 quarts of milk. You can use powdered culture. I tried this once and did not like the flavor of the culture I used. So, I went back to using Stoneyfield. Moral to the story, Choose a yogurt you like the flavor of plain. Not to tart or bitter. But you can flavor the yogurt for eating.
4. Milk. I use fresh raw goats milk. But you can use store bought pasteurized milk.
5. Warm water
6. Thermometer that will read 100-120 degrees F. (not pictured I forgot to get it out)
I LOVE using my oval crockpot with a timer. It fits 2 half gallon jars of milk/yogurt and I can set the timer on it for a few hours at a time and keep checking the temperature. Without worry of forgetting and it overheating and killing the yogurt bacteria.
I have goats and use 1/2 gallon jars to store my milk in. If I am making yogurt right after I milk my goats I just filter the milk into the jars with 1 cup empty for space to add yogurt and to shake it. If I am making it with cold milk already in the fridge I look for a jar that is filled about right and use that..adding or taking away milk so that it is filled to with in 1 cup of full. I use the lines on the side of the jar for measuring. So, I guess that would be 7 cups of milk per jar.. right? grin.
If making a quart you would fill with in 1/2 cup of full...and so and so forth for other amounts.
I have started with cold milk from the fridge and warm milk from the goats, but I never take the time to heat the milk up to a certain temperature like I've seen most tutorials say. I have great results with out adding this step. Nor do I pasturize my milk first by heating it up to 160-170...totally kills my purpose of owning goats. To have raw milk. I've also seen that others Sterilize their jars. I skip that as well, but your welcome to do either of those things. I prefer to save the time and take the risk.
I now add about a half cup of yogurt to each jar. I think I can use 1/4 cup, but I use 1/2. So you're welcome to play around with that. I just plop some yogurt in with a spoon until it is almost to the shoulder. So I know its less than a cup, but probably a bit more than a half a cup. More yogurt means faster culturing, but not faster by so much that I dare dirty a measuring cup to figure it all out. But as long as you have a 1/4 to a 1/2 cup per half gallon you're good. Shake, shake, shake, and shake some more till its good and mixed in. If your re culturing your own homemade yogurt and it stops working, buy new store bought yogurt. I have been able to use my own yogurt culture at least twice before having to buy more at the store. So, about once a month a buy a thing of yogurt at the store to culture with. I make yogurt weekly so that my culture is fresh enough. But things happen and sometimes it starts to weaken and needs replaced.
Put your jar(s) in the crock pot fill with warm or hot (if your starting with cold milk and yogurt this is fine to do) water to the top of the crock pot. The goal is to bring the milk and yogurt up to 110-115F and keep it there for 8-10 hours ish. I have had yogurt done in 6 hours. Probably started with warm milk and super fresh culture. I have let it go overnight as well.
Note you will NOT use the lid to your crockpot.
Turn your crockpot on warm (not low!) and set it for a 1-3 hours or set another timer to alert you for 3 hours if you have no timer on your crockpot or wish to set the crockpot timer for 12 hours. When your timer goes off check your temperature of your water and shake the jars if you want. Shaking is not necessary, but I am toucher, so I shake. If your temperature is too hot (above 115F) it will kill the yogurt culture. If too cold (below 100F) it won't activate it to multiply and turn your milk into yogurt. Once you get used to your particular crock pot, checking on the yogurt might not be necessary. I still do, because the temperature in your home will make a difference in how hot the crockpot gets.
If the temperature hits 115-120 turn the crockpot off for an hour and check back to it. With my GE crockpot and normal air temps (68-74F) I don't have to worry about checking or turning off the crockpot. When we had 90 and above air temps I had to turn off the crockpot every now and again.
The yogurt needs to culture until it thickens up. It will coat the jar and look about like drinkable yogurt you buy at the store. This will take 8-10 hours. Depending on air temps, if you use cold or warm milk, how much yogurt starter you use, and who knows what else. It will not be as thick as store bought yogurt, they use thickeners such as pectin or tapioca. You can add a thickener when you first put the yogurt starter in the milk, if you wish. I don't. I strain my yogurt to remove some of the whey to thicken it. I'll post a how to on that soon!
(insert picture of done yogurt coming later tonight! When this batch is done.)
I like to strain mine thick like Greek yogurt and add sweetener and vanilla for eating or freezing as frozen yogurt. I use it in place of sour cream when I strain it to the thickness of sour cream. I use it for cream cheese when I strain it to that consistency.
I LOVE comments and questions...so comment and ask away. :)