Homemade Crockpot Yogurt

My friend Marissa, over at We*Meat*Again recently suggested I should post about making yogurt. I've been making yogurt pretty regularly for about 18 months now--when I'm in a good habit of it, I make it once a week, every week. But since moving, I've fallen back out of the habit until recently.

Needless to say, at this point I've probably made 40+ batches of yogurt, just under 2 quarts at a time. And it's always come out well, except once when it turned into buttermilk and this past time, when I oops left my crockpot on too long after adding the starter cultures (procured from the last batch of homemade yogurt--but originally just from "live, active culture" yogurt). By too long, I mean overnight. On low. I came downstairs in the morning and had a brown, gloopy, bubbling mess.

Well shoot. Good thing I inherited the milk I'd used from a friend, I guess. It was going sour anyway, which made it pretty ideal for yogurt-making. It wasn't bad yet, but another 24-36 hours and it would've been. It felt less like a loss that way. And thankfully, since the way I make yogurt is pretty low maintenance, but does take a few days, I have a good supply of too-many-additives yogurt.

Marissa wanted me to create a blog post about making yogurt after she realized everything her yogurt had in it--a commercial brand I'll allow to remain nameless. Corn syrup, gelatin, starch, and food dye, among other things. A mutual friend told her she should make yogurt, like I do, in a crockpot. Other friends mentioned brands that are less processed.

To be fair, after making my own yogurt for the past 18 months, I do realize why food companies use some of these thing. I have yet to figure out a really effective way of getting thick yogurt without straining it (this is how Greek yogurt is made--at least if you're making it at home). Fermentation time is a major part of this process though--if yogurt ferments quickly, then it's less likely to hold its whey. More bacteria generally = a faster fermentation time (but this is also dependent on the number of active bacteria) and potentially more runny yogurt. Fewer bacteria = slower fermentation and a thicker yogurt. I've added things like powdered milk (which thickens it some, but also sometimes leaves clumps if I don't get it dissolved enough), but that only somewhat works. Food starch (often wheat-based if it doesn't specify) and gelatin both allow yogurt to come out the way we, as Americans, expect it to be. Thick. And well, gelatinous.

Each batch of yogurt you make will have a little different flavor, based on time, bacteria, and even the milk! That's one of the things I like about making yogurt (and even just buying yogurt, for that matter).

Other things I like about making yogurt:

• I know exactly what goes into my yogurt.
• It's easy & straightforward to make in a crockpot.
• It can use milk that is about to sour, but it's better to use super-fresh milk. 
• It's about the same cost of buying yogurt where I live now, but everywhere else I've lived it's been significantly cheaper to make yogurt than buy it. Even here, it's still a little cheaper.

Heidi, over at 101 Cookbooks wrote a great post about making yogurt back in 2005 and this was the recipe I started with when I started making yogurt. I've never had my yogurt thicken as quickly as she indicates her yogurt fermented (4-5 hours) and re-reading that post so that I wouldn't repeat too much of her information here, it made me a little jealous. But only a little, because honestly since this is crockpot yogurt, I don't exactly invest a lot of time and effort into yogurt-making. Heidi recommends using a yogurt-maker if you plan to make your own yogurt often. I, however, haven't been able to make myself invest in this. Yet. 

Milking Shorthorn in Iowa

The main thing about making yogurt is to keep it at the right temperature while the culture multiplies. This is about 85 degrees. You can wrap a heavy towel around your unplugged crockpot to help keep it at this temperature in most places, most of the year. When I lived in the (very cold) Midwest, I got in the habit of turning it to "warm" or "low" for a few minutes (where I screwed up this time!) a couple of times during the culturing period during the winter because my apartment was too cold for proper culturing--even with the towel (or, a towel and a jacket, even). The other thing to make sure of is that you heat the milk enough to begin with--various sites will tell you between 170 and 185 degrees. Try to avoid letting it boil (but, if it does, you'll probably wind up with a lightly caramelly flavor in your yogurt), though the milk should look frothy.

After your yogurt has cultured, you can move into a new container and store it in the fridge. The recipe below assumes you have a crockpot that can hold about one-half gallon of milk.

Crockpot Yogurt

3 1/2 cups organic milk

1/2 cup organic yogurt with active cultures (your starter--I've used Stonyfield, Nancy's, Mountain High, and others that are locally available)

Heat your milk in your very clean crockpot on high for 1 hour and 15 minutes. Turn off & unplug the crockpot and leave covered until the milk cools to about 100 degrees. Depending on the time of year and the heat of your house, this will probably take about 2-3 hours.

Meanwhile, bring your starter yogurt to room temperature (this helps it mix better into the warm milk). When you do this, make sure that your starter yogurt is in a clean, covered container.

Stir your starter yogurt into your cooled milk, then wrap your crockpot in a heavy towel. Let sit 4-8 hours. If your home is particularly cold, you should probably turn the crockpot to warm or low for 3-5 minutes about halfway through the culturing process. Check your yogurt. If it looks thick* (be careful not to jiggle or stir it at this point--this might result in stringy yogurt) then it's done. If not, heat the crockpot just a little (another 3-5 minutes on low or warm and then unplug the crockpot again and re-wrap it) and leave up to another 8 hours.

Transfer the crockpot to the refrigerator to allow the yogurt to fully set** and then transfer yogurt into a container for storage.

*I can usually tell by the drops of moisture from the crockpot lid that drip when I lift it up.

**I've only done this a couple of times and it results in a slightly thicker, creamier yogurt, but I haven't experimented with this often enough to know if it's a thing that always happens, or if it's dependent on the type of culture I'd created those times. Usually I just transfer it straight into the container meant for permanent storage. If you experiment with this, please let me know your results!