Step 4: Incubate

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Incubate the yogurt at 110-115 degrees F for the next 6-8 hours, up to 12 hours for a tarter flavor. I've found that my heating pad inside a cooler maintains this temp perfectly. However, most heating pads will have an automatic shut-off, so you'll have to babysit it a bit. Pack any dead air space in your cooler with wadded up towels for better insulation. My long probe thermometer is resting right against the side of one of the jars.

You could also try setting them in the oven, if you can set the heat that low. If you're just itching to spend lots of money, you could buy a commercial yogurt maker, which I believe maintains a constant temp as your jars incubate in a water bath. I prefer my free setup, using common household items.

That's it! Refrigerate the yogurt and it should keep for at least a month or two. You'll notice that the curd separates out from the whey after it sits awhile, so give it a stir and you're good to go. This makes a great base yogurt to blend with fruit, granola, etc. It's also good over cereal in the morning, or whipped up as kind of a yogurt drink.

Finally, you can pour the finished yogurt into a strainer lined with cheesecloth and let it hang for several hours to make a "yogurt cheese" that is much like cream cheese.  You can make the plain version of this yogurt and then add any sort of flavorings to the finished cheese for a fancy spread. 
Let me know what you think!

I made some! I used the Trader Joe's plain french cream line yogurt to inoculate. Basically put one pot inside of another pot filled halfway with water and heated the (store bought) milk to 180 (candy/fryer thermometer) for a few minutes and stirred in a couple TBS of some brown and white sugar. Put that inner pot in a half sink of water which cooled it to 110F in a few minutes, stirred in my yogurt. Let that sit in the pilot lighted oven for 7hours at 102F.

The yogurt came out soooo good! My only problem is that I ironically got distracted by destructables for a few minutes and i think my milk scalded and a bit of skin formed on my milk and the edge of the pot. I think this caused some tiny lumps in my yogurt, either that or not stirring the inoculator in well enough.

Any idea how to prevent that next time? Otherwise my yogurt is (about to be WAS) sooo good! Thanks for your instructable!
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I was definitely just gonna wing it on this one. Now all I need to do is pick my favorite yogurt to culture the milk. A couple questions tho.

Is it necessary to boil the milk, as a fresh jug should be pasteurized/homogenized already?

How important is sanitation when you're introducing a hardy and highly concentrated bacteria Lacto. acidophilus, into the mixture?

morgano (author)  omgitzstegman5 years ago
Well, you're right that milk from the store will be pasteurized already, so you could probably skip that step and just warm it up to incubation temps. I like to be as sanitary as possible, just to be safe. We often start with milk straight from the bulk tank of a dairy farmer, in which case it needs to be pasteurized. As far as the INCUBATION temp goes, I've found that our oven will stay right around 100 degrees with just the light on and the door closed, which is about perfect.
reelthing6 years ago
If you have a gas oven, the pilot light gives off enough heat to work perfectly. If not, I have a friend who wraps a towel around container and places it on her hot water heater. She says that works as well.
sheilarae6 years ago
I like your complete, concise, easy to understand directions and your photos are great! I'd love to have a demonstration of this whole process, but with your excellent instructions, I feel comfortable enough to try it by myself!