In our house, we eat a LOT of yogurt. I usually have some every day, either in a smoothie, or with some of my favorite granola and some fresh fruit or homemade jam stirred in. Plain is the name of the game in our house (I find the commercial flavored kinds sickeningly sweet), and always organic. Have you ever looked at the list of ingredients in some of the non-organic flavored yogurts out there? The kinds billed “Light” are the worst offenders. Yuck.
One week this past summer, I gazed upon our ever-growing stack of empty yogurt containers (we were saving them for transplanting our vegetable seedlings into) and thought to myself, oh man, there has got to be a better way. Besides the obvious expense of going through that much yogurt each week, the amount of plastic containers building up just didn’t seem to me to be very sustainable. We try to be conscious of our impact on the earth, in whatever ways we can, and accumulating that many plastic containers just seemed to be kind of wasteful. Beyond that, I was just curious! I knew there were yogurt making machines out there, but I’m all about learning to do things myself (plus, I try not to accumulate machines in the kitchen that serve only one purpose – with the exception of our ice cream maker, of course.) Doing a little bit of research, I discovered that people have been making yogurt as a means of preserving milk for literally thousands of years – since 2000 BC! – and honestly, it’s easy! The main things you need are a milk you like (I usually use organic 2% milk), a starter culture of yogurt (which can be any plain yogurt that contains active live cultures, either storebought or some of your last batch of homemade yogurt), a way to measure the temperature of the milk, and a way to maintain temperature in the yogurt while it incubates for 4-6 hours. There are a few different ways you can do this, but I’ve had great success using a simple electric heating pad that I picked up for about $10 at CVS. (The heating pad also comes in handy when I’m making bread; it keeps a warm, constant temperature around the bowl while the dough rises.)
And, homemade yogurt is utterly delicious. It’s milder in taste than storebought plain yogurt, not sour. It has a wonderful creamy, smooth consistency, not as gelatinous or stiff as the storebought yogurt. And the beauty of it is that you can completely customize it according to your tastes. Like it very thick? Add more powdered milk. Want to sweeten it a little bit? Add some honey or maple syrup. You can stir in any jam or preserves to make flavored yogurt. I made a batch this past weekend, and tried to take photos as I went along — so I hope you enjoy, and if you love yogurt as much as we do, maybe you’ll try to make your own this year, too!
Equipment and materials: get these all ready before you start.
1. A large heavy stockpot, washed and clean.
2. A skillet that will hold a spoon, candy thermometer, and whisk. You could get away without a whisk if you wanted, but I use it to whisk in powdered milk. You’re going to sterilize these tools in this skillet, so the skillet should be deep enough so the tools can be submerged in water that you’ll boil. I use a 3 quart skillet.
3. An electric heating pad (I bought mine at CVS for about $10), and a few clean dishtowels. Have your heating pad set to the highest setting so it’s warm and ready to go.
4. Your choice of milk. I usually use Organic Valley 2%, but you can use skim or whole milk. I use a half gallon of milk at a time, which will make a little over 8 cups of yogurt.
5. Powdered milk – this thickens the yogurt up a bit. I use Organic Valley nonfat dry milk, and a resealable pouch like this has lasted me just about 6 months.
6. Half a cup of starter culture (plain yogurt), in a liquid measuring cup. The first time you make it, you will use a storebought brand of plain yogurt that has live active cultures. I’d recommend Stonyfield Farm plain organic yogurt, as it has 6 kinds of live active cultures. These live active cultures – varieties of lactobacillus bacteria, to be more specific – are important, as they’re the bacteria that will turn your milk into yogurt as it incubates. Once you’ve made your first batch, you can save a 1/2 cup portion each time and use it as the starter for your next batch.
7. You’ll need some containers to store your yogurt in, in the fridge. I use glass Pyrex containers, just because that’s what we usually use for storing food.
8. An ice water bath. I fill up one basin of our kitchen sink about halfway, and dump in ice cubes. The ice water bath will be used to cool down the milk before you add the starter culture.
Once you have all of the above equipment and ingredients gathered, you’re ready to start!
The Process
1. Take your milk and starter culture out and have them at room temperature.
2. Now, you’ll sterilize the utensils to be used in the milk. To do this, place your thermometer, spoon, and a small whisk (if you want) in the skillet and fill the skillet with water so the parts of the tools that will touch the milk are submerged underwater. I also lay a pair of metal tongs in along the side; I’ll use the tongs to lift the tools out of the boiling water. Once the water reaches a boil, let it boil for 1 minute before removing the tools.
3. Once your tools are sterilized, lift them out of the boiling water with the sterilized tongs, and set them on one of the clean dishtowels.
4. Place the milk in your heavy-bottomed stockpot, and shake in about 1/4 cup of powdered milk. Start this mixture heating over medium-high heat.
5. Place your thermometer on the side of the pot so it’s submerged in the milk.
6. Using your sterilized whisk (you can use a spoon, but a whisk works better), mix in the powdered milk until there are no more lumps.
7. Continue heating the milk mixture, stirring occasionally. You want to bring the temperature to just under boiling – 185 degree F. This will kill off any unwanted bacteria that might be in there.
8. Once the milk mixture reaches 185 degrees F, keep it there for 1 minute, then remove the pot from the heat and transfer the pot directly into the ice water bath. Stir the milk mixture until the temperature comes down to between 120 and 115 degrees.
9. Transfer the pot to the preheated heating pad (I usually place a dishtowel on top of the heating pad, which I rest the pot on.)
10. Use your spoon to transfer 1/2 cup of the warm milk mixture into the liquid measuring cup containing your starter yogurt. Mix the warm milk into the starter yogurt until it’s pretty smooth.
11. Now, pour the warmed starter yogurt/milk mixture back into the pot, and stir thoroughly to combine.
12. Put the lid on your pot, and wrap the pot in a few dishtowels. Keep the pot, wrapped in dishtowels, on the heating pad for 4-6 hours. The yogurt should stay around 105-110 degrees F for this entire time, which is why I wrap it in dishtowels – they help insulate it. If the temperature drops much below that, it will be too cold for the bacteria to work; too much higher, and the bacteria will be killed. The yogurt should be set after 4 hours; leaving it longer will develop a bit more tang. I usually leave mine for 6 hours.
13. After 4-6 hours, your yogurt is ready! Stir it well with a spoon to create a smooth, even texture. It will seem fairly loose at this point, but will firm up overnight in the fridge.
14. After you’ve stirred it thoroughly, transfer the yogurt into your containers, and place them in the fridge overnight.
15. Make sure to reserve 1/2 cup of the yogurt to use as a starter for your next batch. If you want to make sure no one accidentally eats it, you can always put a little note on the container. 
And that’s it! Start to finish, I find the prep process (not including incubation period) usually takes me about 30 minutes. The yogurt lasts us about 2 weeks, and like I said before, it’s really delicious! I love the fresh, creamy taste and consistency, and the way I can tailor it to my tastes however I want. If you’re inside on a rainy or snowy weekend this winter, it’s a great time to try making your own!
More yogurt information:
History and Folklore of Yogurt Making (Stonyfield Farm)
Make Your Own Yogurt (Mother Earth News) – detailed step-by-step description of the process, as well as alternate methods of incubating your yogurt if you don’t have a heating pad
Homemade Yogurt (101 Cookbooks) – more interesting information about yogurt, as well as a “tasting notes” sheet you can use for your homemade yogurt experiments.
