This is another installment in the “Fun with Dairy” series. I’ve made yogurt at home for years. Homemade yogurt is so much better than its store-bought counterpart, it’s astonishing. You can find any number of directions on the internet for making yogurt at home, and because of that, I’ve resisted blogging about making yogurt. But because so many people ask me how I do it, and because not all methods of making homemade yogurt are good ones, and because I’ve found a method that works without fail for me, I’ve decided to share it.
First, here’s what you need to make homemade yogurt:
Two pots, one large enough to hold the other, and the top one, the one you’ll cook the milk in, should be non-reactive (stainless steel, glass, enamel or porcelain-coated)
A candy thermometer (not strictly necessary but helpful)
A stainless steel spoon (don’t use wooden or silver spoons)
1-2 quarts of milk
1-2 tablespoons of plain, active-culture yogurt
Making yogurt isn’t difficult, but there are some important things to know. I’ve only had one failure in years of making it at home, and that one time was because my stove hood was dirty; the steam from the water jacket condensed on it, and a drop of dirty water fell into the milk. That batch never thickened, and that little lesson taught me just how fragile lacto bacilli actually are. They do not like competition from other bacteria! (It also taught me to clean my stove hood before a yogurt-making session.) I’ve read about making yogurt in a crock pot. I cook meat in my crock pot—and remember, lacto bacilli do not like competition from other bacteria. It would be difficult and much more time consuming to sterilize the crock pot vessel than to use two separate pots. I once tried making it on the stove without the water jacket, and the milk had a tendency to scorch before it got hot enough unless it was stirred constantly. So here’s the water jacket method I use, and it’s actually pretty easy. You can walk away from it and do other things while the milk is heating, and it will never scorch.
I fill my 13 quart stockpot 3/4 full with hot water, and start it heating on high. I invert my 6 quart stainless steel soup pot over that, stick my stainless steel spoon and candy thermometer into the boiling water, and let it boil for 10 minutes to sterilize the inverted pan and utensils.
Then I turn the top pan, draining the condensed steam out of it, and put it into the bottom pan, so I have a big double boiler. The thermometer and spoon go in the top pan along with 1 or 2 quarts of milk, depending on how big a batch of yogurt you want to make. Milk of any fat content can be used, although more fat produces a thicker, creamier yogurt. I usually use 1% milk.
Then, with the large pot underneath boiling, the milk heats in the top pan. Stir and skim off the milk skin occasionally, until the milk reaches a temperature of 170-185 degrees. I live at altitude, so the best I can ever do is 180 in a water jacket set-up. This heating kills off any bacteria left in the milk that would interfere with the lactobacillus reproduction. I think this is less important with store-bought pasteurized milk, but I always do it anyway. (If you don’t have a candy thermometer, and have no plans to buy one, you want to heat the milk until it is very frothy.)
Then, the milk has to cool down to 110 degrees. It’s very important that the milk be cool enough when the yogurt culture is added, or the l. bacilli will die. It is also important that the milk be warm enough to wake up the yogurt culture. It’s kind of like Baby Bear’s porridge: it has to be just right. You can place the pan containing the milk into a bowl of cold water to hasten the cooling process if you’re in a hurry, but keep monitoring it, or it will cool too much and have to be reheated. I put mine on the cold marble slab in my kitchen and keep scooting the pan around on the slab to find another cool spot after 5 minutes or so. (Usually, I’m loading or unloading the dishwasher while I’m waiting for the milk to cool, so no time wasted there.) I’ve made yogurt without a thermometer, and I learned that the right temperature is just a little warmer than blood heat. If you’ve ever seen or heard of testing a baby’s bottled milk on your wrist to see if it’s the right temperature, this is the same thing. Just dribble a little of the milk on your wrist. For babies, the milk should feel neither cold or hot—that’s blood heat, about 98 degrees. For yogurt, the milk should feel warm, but not hot on your wrist. That should be about 110 degrees.
For the starter, use only plain, active-culture yogurt. It can’t have sugar or pectin or anything in it except milk or cream, and active l.bacillus cultures, but again, any level or percentage of fat in the starter yogurt is fine. I often use non-fat yogurt as my starter when I need a new culture. Use 1 tablespoon yogurt as starter to each quart of milk.
Gently stir the yogurt into the heated and cooled milk, cover with a tight-fitting lid, and put the pan in a warm, cozy place to culture for 8-24 hours. Don’t move it or stir it while it is culturing. 8 hours will create a yogurt that firms up when cooled in the fridge, but a 24 hr. culturing period eliminates virtually all of the lactose in the milk because those beneficial critters eat it all up.
Some attention to the various ways to keep yogurt warm enough while it is culturing is in order here. A temperature of about 80 degrees is ideal. Some people put their yogurt in a warmed oven which is then turned off, but the light is left on. Some folks with gas ovens say the pilot keeps the oven warm enough. Others use heating pads (you have to have an old-fashioned one that doesn’t have an auto shut-off for this to work, and let’s face it, they’re a fire hazard), and still others are able to use the top of the fridge, which is usually warm. If the house is warm enough, the yogurt may be fine on the countertop.
My house tends to be cool, so I’ve worked out a couple of different methods that work for me at different times of the year. In the winter, when the heating stove is on, I park the pan, covered with its tight-fitting lid, on the slate hearth. In the summer, when the cooler is running, I put the pan in my laundry room (which doesn’t get any cool air from the swamp cooler) and stash it on top of or next to the big freezer, which pumps out a lot of heat. In the spring and fall when the laundry room is too cold or the heating stove is not yet in use, I use a drinks cooler. This is an easy method that can be used all year round. A portable cooler will keep heat or cold in, as required. In this case, we want to keep in heat. I fill the empty milk carton with the hot water from the big pan (the water jacket), stash it in the cooler next to the covered pan of yogurt and close the lid. 24 hours later: yogurt. No muss, no fuss.
When the yogurt has finished culturing (it should be fairly solid, other than a bit of whey on top, when you tilt the pan), whisk the finished yogurt to smooth it out, then pour or dip it into clean containers, and chill in the fridge. Don’t worry if the yogurt seems thin after whisking. It thickens again as it cools. For Greek-style yogurt, you can drain it right away through a cheesecloth-lined colander if you wish, or cool it and drain it later. If you drain it long enough, you’ll end up with a yogurt cheese, a soft, spreadable cheese reminiscent of goat cheese, which can be served on crackers plain or flavored with herbs and other additions.
As the yogurt sits in the containers, whey rises to the top. This should just be stirred back into the yogurt unless the whey is desired for a different fermenting project. Always save a couple of tablespoons of yogurt for the next batch. The yogurt shouldn’t be more than a month old before it’s used for a new batch, or the lacto bacilli might die. If a batch of yogurt is too thin after chilling, it’s time to buy a new container of plain, active-culture yogurt at the store for a new starter. I do this about every 3-6 months. I guess the critters just get tired.
I am never without homemade yogurt in my fridge. We’re hearing a lot about probiotics these days and the health benefits of a strong immune system that’s boosted by probiotics. Homemade yogurt is probiotic, but more than that, it’s delicious.
I eat a small bowl of homemade yogurt every night. I usually mix a spoonful of one of my low-sugar jams (raspberry, peach, apricot, strawberry, nectarine, and various other combinations) into my yogurt, but my favorite thing to mix into it is homemade lemon curd. Tart, slightly sweet, creamy, lemony goodness. It’s dessert that’s good for you.
But I also do a lot of other things with my homemade yogurt. I use it in my coleslaw dressing, in my sourdough starter, as a replacement for sour cream if I’m out, in clafoutis (a wonderful French country dessert), in dips or as a spreadable cheese, and in many other dishes. At some point, I’ll pass along those recipes, but for now, I hope this post has given you the impetus to try making something really good for you at home. And just so you know, if the yogurt fails to culture for some reason, you can still make ricotta out of the milk, so nothing is wasted.