Make Yogurt in a Thermos? Why Not!

Last week for “Stove Sundays” I showed how to make yogurt in a dehydrator. Yes, it can be done. In fact, there are all sorts of makeshift ways to make yogurt at home, some more creative than others. Today, I figured I would expand on the idea and show how to make it in a food thermos, such as this Thermos King 16-ounce Food Jar:

Granted, it’s a smaller one and if I wanted to get more serious about yogurt making in a thermos then I would opt for a larger one for sure, such as this 40-ounce model. No big deal, I really just wanted to experiment with it.

FYI, there are off-grid ideas for making yogurt that do NOT require electricity to incubate the yogurt. For example, this Yogotherm Yogurt Maker is one such option which I found referenced here:

The more I looked at it the more I decided it looked like a fancy thermos. And since I didn’t want to spend $50 on this if I didn’t have to, that’s where this thermos idea came from.

Also, I do want to point out that I wound up doing this experiment twice because the first time I tried it, though it seemed to worked, I was a bit worried about the general outcome… I’ll explain in a moment.

Ingredients

Remember that this food jar doesn’t have much space at all so I choose to halve the ingredients from last time, yielding only about a cup. You can/should adjust the ingredients to make more so that this idea is worth your time. That said, it may be worthwhile to try it once or twice with fewer ingredients to get the hang of it.

Now, here’s what I did (you can read last week’s post for explanations of ingredients):

• 1 cup whole milk (best not to use skim or low fat)
• 1/2 tablespoon PLAIN yogurt culture (make sure it’s fresh)
• 1 candy thermometer
• frozen fruit for flavoring
• sweetener (e.g., honey, agave nectar, maple syrup)

Instructions

Reference last week’s post for discussion on the following steps 2-4, 6, 8 (though they’re not the same numbers).

1. Before doing anything, preheat the thermos by filling with hot water and set aside. It should be plenty ready by the time you pour in the yogurt. Not preheating it will probably make the temperature drop enough to stop the yogurt from multiplying but I haven’t tried it.
2. Scald the milk by bringing it to 180 degrees Fahrenheit.
3. Remove from heat, cool to 110 degrees Fahrenheit.
4. Remove a portion of the milk (say 1/4 cup) into a measuring cup and add yogurt culture. Stir gently. Return mixture to pot of milk. Stir gently again.
5. Drain water from thermos as best you can. (You could dry it out but that might contaminate the thermos.) Pour milk into thermos. Put on cap. While you’re probably ok just to leave it sit out on the counter, I choose to further insulate it by placing it in my “wonderbox” cooler. Is that necessary? Probably not, I’m just being overly cautious.
6. Leave it alone for 4-8 hours to allow the yogurt culture to incubate and multiply.
7. This is the IMPORTANT part: transfer yogurt from the thermos to something else, preferably a clean mason jar. I learned this the hard way when I simply choose to move the thermos to the fridge after incubation the first time I tried it. When I checked on the yogurt the next morning I found that the yogurt was still NOT cold! Though the small bit I tried seemed to taste ok, I wasn’t sure if it was spoiled somehow since the yogurt had effectively “sat out” for well more than 12 hours. Gee, I guess that’s why an insulated thermos is such a useful item. 😉
8. Mix in fruit and/or sweetener to taste.

That’s about it. If you want to see photos of some of the steps you can read last week’s post. Otherwise, everything is the same as in a mason jar except I used a thermos.