Making your own yogurt is quite simple! It does take a little time, but most of it is inactive. It’s a really fun, easy project to try at home at least once!
1. Heat the milk to about 77C (170F). If you don’t have a thermometer, then heat the milk until it just starts to simmer around the edges.
2. Cover the pot with a lid and let it cool down to 43C (110F). Then stir in the yogurt. Now you just have to keep the yogurt warm, and wait about 5-10 hours.
3. You can warm up your oven very slightly (to about 43C / 110F), turn off the oven and leave it in there. Or, if your oven has a setting for letting bread rise, you can use that. My oven in Japan has that kind of setting, called 発酵, hakkou, or ‘fermentation’, which will keep your oven temperature at 40C. I used that setting for a little while, then turned off the oven and left the pot in there with the door closed until it was done. Or, if you don’t have an oven or don’t want to use it, you can wrap the whole pot (with the lid on) in a heavy towel, and leave it in a warm spot. I’ve done it that way before with no problem.
4. Check the yogurt once in a while to see if the milk has congealed. There might be a little whey on top (a clear yellow-green liquid), which you can pour off. At this point, you’re done! If you want to make Greek/strained yogurt, you can strain it by putting cheesecloth or coffee filters in a strainer, setting it over a bowl, and letting it sit in the fridge overnight.
If you don’t strain your yogurt, you’ll get about the same amount of yogurt as the milk you started with. If you strain it, a lot of whey will come out. I started with a liter (4 cups) of milk, and ended up measuring 560mL (2-1/3 cups) of whey, leaving about 410g (1-2/3 cups) Greek yogurt. (It does depend how thick you like it, so your results may vary.)
So, is it worth it?
If you’re currently buying Greek yogurt, then it’s worth it. Or, if you don’t strain your yogurt, it’s worth it. In those two cases, making your own costs about 1/3 as much as buying in the store!
If you want to strain your yogurt, here are the numbers I got. This will, of course, vary slightly depending on the price of milk and yogurt in your area.
Buying Greek yogurt in the store: 1.35 yen/gram
Buying yogurt in the store and straining it: 0.5 yen/gram
Buying milk in the store, making yogurt, and straining it: 0.4 yen/gram
So it’s much cheaper than buying Greek yogurt, but only slightly cheaper than buying yogurt and straining it. If you add in the extra effort of making your own yogurt, each person will have to decide whether they think it’s worth it. For me personally, I probably won’t make yogurt every week, but once in a while I will.
How about taste? Well, I love the taste of the homemade yogurt. I don’t really like a very strong sour, yogurty taste, but the homemade yogurt is very mild. It tastes very fresh and pure. I like to eat it with a little honey and some toasted walnuts (like in the picture above), or mixed with fresh/dried fruit, jam, or nuts.
Especially in Japan, I use strained yogurt a lot – not only for eating, but also as a substitute for sour cream or cream cheese in certain applications. You can make dip with yogurt (mix with a little mayo and some seasoning) and no one can tell the difference. You can make tzatziki (a Greek yogurt cucumber sauce). You can also strain it a little further and make a spread for crackers that’s like cream cheese. You can even make cheesecake with it. You can put a spoonful of it in soup to make a creamy contrast; you can use it to make pasta sauce; you can use it in tacos or burritos; you can make a creamy salad dressing with it; you can…