The first time I tried to make yogurt at home, I assumed, as a matter of course, that it wouldn’t work. Milk is just so darn liquid—it’s hard to imagine that with a bit of heat and time, you might make a creamy, thick solid, something to hold up your fruit or embrace your granola.
There are as many ways to make yogurt as there are to eat it (that is, a lot). Some require thermometers and a fair amount of attention; you can buy yogurt-making devices or use a crockpot. My yogurt-making philosophy tends toward the laissez-faire. After all, it’s really bacteria doing all the work; my job is simply to warm them up and get out of the way.
Typically, the bacteria you’re trying to fire up when making yogurt are thermophilic bacteria, which become active between 110 and 115 degrees; these bacteria are introduced via a starter culture. In The Art of Fermentation, Sandor Katz suggests finding a traditional yogurt culture that will survive batch after batch. If you lack such foresight, ¼ cup of store-bought yogurt works. (Be sure you’re buying yogurt with “live and active cultures.” I usually go with Nancy’s Organics.)
Before you add your culture, you want to heat your milk to about 180 degrees—which is when it starts to swell and almost bubble. “What this heating accomplishes, aside from killing native bacteria that could compete with the introduced cultures, is to alter the structure of the milk protein, casein, a key to thick, firm yogurt,” writes Katz.
I start with a half-gallon of two percent milk (fat helps the yogurt cohere, so whole milk is even better) and a large saucepot. The saucepot goes on the stove—set to medium heat—and the milk in the pot. Twenty minutes later, give or take, when the milk starts barely bubbling—at 180°, it should feel hot but not burning—turn off the stove.
You can also use your crockpot to similar effect. Add milk, cover, turn to low, and let sit for about two hours. After you heat milk to the point that its proteins de-nature, you want to cool it to a point that it’s hospitable to a starter culture, which will re-wind those proteins into a solid structure. That point is about 110°, which feels like warm skin. After you turn off the stove, let the yogurt sit for a bit—say, 30 minutes.
Once it gets to this point, you’ll add the starter culture and try to keep whatever receptacle your milk is sitting in as close to that 110° temperature as possible. For me, that usually means turning on my oven for five minutes, swaddling my pot in a wet dishtowel (bacteria love humidity) and sliding it into the warm oven and then promptly forgetting about it. If you’re using a crockpot, the heat of the ceramic dish should keep the milk warm enough; wrapping it in a towel will help.
When I wake up the following morning and open the oven, I’m greeted with a slightly tangy smell—and a saucepot full of solid, shimmering yogurt. While it’s still slightly warm, I usually add a heap of honey or agave syrup, a dash of cinnamon, and a teaspoon of vanilla extract. Spoon the yogurt into jars or containers and refrigerate for a few hours; it’ll solidify even more. That is, if your granola can wait that long.
Megan Kimble is the managing editor of Edible Baja Arizona.