Finally, Fermentation: Making Yogurt at Home

When I was reworking the template for this site, trying to make it a little more blog-y and a little less Angelfire/Geocities, I added the subtitle “Family // Fermentation // Faith” mostly because those are the things I like to spend my time thinking about and doing, and also alliteration. But while I’ve written a lot about family and a little about faith, I haven’t touched on fermentation, which is completely nuts because HAVE YOU MET ME?

At one point a couple weeks ago, we had a sourdough starter, lacto-fermented red cabbage kraut, yogurt, goat cheese, and plum vinegar all fermenting in the kitchen, plus all manner of pickles hogging counter space, a whole heap of homebrew supplies occupying the top of the fridge, not to mention the fermented and fermentables we buy from other people: sour beers and pet-nat wines and raw milk cheese and shrubs and ciders and miso and and and and. We’re not even the most ferment-obsessed people we know.

I’m actually not particularly skilled at the “set it and forget it” variety of fermentation–chop some cabbage, toss with salt, weigh down, and boom! kraut! or mix up some flour and water and leave in a corner of your kitchen, feeding with more flour and water, and boom! starter!– mostly because those are the exact two steps I am able to do: 1) Set it; and 2) Forget it; with primary emphasis on the second step, and zero attention paid to the unwritten third step which is 3) Unforget it, because you actually need to check on it, oh whoops, now your starter is covered in some crap called hooch and your kraut wasn’t submerged enough and has become a giant slime pile that smells like the annual convention of all farts ever to have existed in the world.

Somehow, though, the 30-minute-squeeze-into-naptime-after-you-snarf-a-PBJ-and-maybe-take-a-shower-jk-about-that-shower project tends to typically work out, such that I’ve been able to consistently make yogurt and occasionally make cheese for us. Yogurt is a couple of ingredients, just a few steps, and lots of fun to make (I mean, for people like me who delight at milk being turned into other things, which I assume you are, too, if we’re friends.)

Here’s what you’ll need to get started:

  • Half-gallon of milk, not ultra-pasteurized
  • Half-cup of your favorite plain yogurt
  • Glass jars for storing yogurt
  • Double boiler or a metal bowl that can fit snugly atop a pot
  • Kitchen thermometer
  • Some kitchen towels or cloth napkins or those receiving blankets you brought home from the hospital because, seriously, what else are you using them for?
  • A warm spot (between 90°F and 110°F)– a gas oven with a pilot light works great, or you can start the preheating cycle on an electric oven at the lowest temp for a couple of minutes, turn it off, and shut the door. Other people have used crock pots, coolers, heating pads, lots of towels, etc., for incubating yogurt– just don’t start a fire or anything, and make sure your temp is around 100°F so that the cultures can incubate and thicken within a relatively safe time frame. 

A few notes:

There are only two ingredients in yogurt, so try to make them the best you can! Homemade yogurt is so much less expensive than store-bought that you can afford to go schmancy on the milk. Also, full fat, for the love of God. This is not 1985.

Unstrained, the yield is pretty close to 1:1 milk to yogurt, meaning that a half-gallon of milk will yield close to half-gallon of yogurt.  You can easily cut the recipe in half, if you don’t go through yogurt like I do, which is akin to the yogurt intake of a professional yogurt eating team in spring training.

You can use any plain yogurt with live cultures to culture your yogurt, whether it’s strained/Greek or not, but I like to choose something I like the flavor and texture of unstrained, because it’s a more clear indication of how your own yogurt will turn out unstrained.

Okay, on with the show!

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Make sure everything you’re using– jars, lids, pot, bowl, double boiler, any spoons or spatulas, thermometer probe, etc– are all cleaned and sterilized.  Since you’re trying to grow microbes in your yogurt, you want to get rid of anything extraneous–your kitchen has plenty of microbes that can cause wonky stuff in your finished yogurt, but those things are easily controlled with a good wash and sanitizing routine. I wash with hot and soapy water, and then sterilize either in boiling water or according to the package instructions on something like Star San Sanitizer, which you can use if you homebrew, too.

If you go with cream-top or unhomogenized milk, you can either leave the hunk o’cream in the milk as you warm it, or scoop it out and use it in your coffee or spread it on bread or something equally delicious, which is what I usually do.  Sometimes that extra butterfat doesn’t totally integrate into the yogurt once it’s chilled, and leaves little unincorporated globs of fat on the top of the yogurt.  Not the worst thing in the world, but I prefer to use it elsewhere.

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Fill the bottom of a double boiler or a stockpot with hot water (no need to go with cold from the tap, since you’re just using the water to heat) and place over high heat. Fill the top of the double boiler or the metal bowl atop your pot with milk.

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Heat the milk to between 180°F and 195°F.  You’re essentially re-pasteurizing the milk (or pasteurizing it for the first time, if you’re starting with raw), not because you hate raw milk and its proponents, but because you’re going to introduce live cultures and leave them at a temperature at which you want them to get comfy and grow– so you only want the cultures you’re introducing to grow, not any random hangers-on.  This step creates a blank canvas for your yogurt.  It also serves to denature some of the proteins in the milk (similar to the way that heat helps to denature proteins in whey when making ricotta), which will help the yogurt coagulate later.

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Remove the top of the double boiler or the bowl containing your milk and set to cool on a trivet or heat-safe surface.  If you’d like to speed up the cooling process, you can place the bowl of milk in a container of cool water and stir gently.

Cool the milk to between 100°F and 115°F and gently stir in your yogurt. Stir up and down, back and forth, and around, so that the yogurt is evenly distributed throughout the milk. Pour the milk and yogurt mixture into your jars, and place the lids on top. Wrap with kitchen towels/cloth napkins/receiving blankets/cloth diapers (jk, kind of), and place in your oven with pilot light or other warm place. We keep a thermometer in our oven so that I can tell what temp it is, which I highly recommend.

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I like to stick the jars on a sheet pan so that they don’t wobble too much when pulling the rack in and out of the oven.

Leave the jars in the oven for six to eight hours.  If I’m making yogurt during the day, I’ll check it after six hours to see if some whey has started to separate, if it’s thickened, and if it’s as tart as I’d like, and if not, I’ll let it keep culturing for another couple hours.  If I’m letting it culture overnight, though, I’ll just put it in the oven before bed, and check it when I’m up (assuming that’s a full eight hours and Winnie didn’t wake up at 4:30 am again.)  When you check the texture, keep in mind that it will continue to thicken once cooled in the fridge.

During this incubation period, the second transformation (following the transformation through heat that we initiated earlier) is taking place: the live cultures in the scoop of yogurt you added are eating the lactose in the milk, and converting the lactose to lactic acid.  Then, the lactic acid is changing the structure of the proteins in the milk, breaking them apart and reforming them, thickening the milk into yogurt. It’s the same sort of thing that happens in creme fraiche, and it’s one of the beginning steps of cheesemaking, too.

I’ve recommended six to eight hours because that’s what’s worked for me, but you could experiment with shorter or longer culturing times, as well– keeping in mind that longer times may carry a small food safety risk, since you’re keeping a high-moisture product in the temperature “danger zone” for a longer period of time, though acid production would mitigate the risk on some level.  Anyway, you do you, and your yogurt, too.

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When your yogurt is done, you’ll notice a little bit of yellow-ish, clear whey starting to separate.  You can either pour this off, strain it out (I like a fine mesh strainer as opposed to butter muslin or cheesecloth– easier to clean), or stir it in.  Your yogurt, your call.

Homemade yogurt with Blenheim apricots, dried wild Maine blueberries, and a drizzle of raw honey

 

Make sure to scoop out a smidge while it’s still warm– it’s one of the singular delights of making your own yogurt at home.

Check out these resources for other methods and more info:

Homemade Yogurt | David Lebovitz 

The Science of Great Yogurt | Brod & Taylor

Interview with Sandor Katz | The Splendid Table

Fermenting Yogurt at Home | National Center for Home Food Preservation

Happy yogurting!

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