Get the Recipe
As a cruise down the dairy aisle will quickly attest, Americans are infatuated with Greek yogurt. (Whether or not what's on offer is actually Greek yogurt, Greek-style yogurt, or "just garbage that tastes nothing like what I ate that one summer in Santorini" is a debate we shall leave aside for this post.) If you're on this particularly trendy dairy bandwagon, those little lunch-packable six-ounce cups priced around $1.49 a pop can claim a serious chunk of your grocery budget and represent a distressing volume of packaging in your trash can.
Producing yogurt at home may not be quite as simple as making ice cubes, but it's not much more complicated than measuring liquid into containers and letting it reach or hold certain temperatures. Ultimately, if you can stir and read a thermometer, you have all the skill needed to culture your own.
That being said, there are myriad ways to get from milk to yogurt and your results will vary depending on a number factors, so a certain period of trial may be needed until you land on the taste you like and the process you find most efficient.
Things to Consider
What type of milk will you use? You can use whole, reduced fat, or even skim milk (you can also culture non-dairy milks such as almond or soy), though the taste and thickness of the resulting yogurts will differ. Some people mix in a portion of dry milk before culturing to further thicken their yogurt, but I have never found this to improve the texture; if anything, it seems to add an unpleasant grittiness no matter how well I think I have dissolved it.
What type of starter will you use? You can purchase freeze-dried yogurt starters or use a few tablespoons of a plain store-bought yogurt. If you decide on the latter, select one with a taste you like and check the label to make sure it contains live and active cultures before purchasing. I've had good experiences with both methods.
How long will you let it incubate and how will you keep it warm enough (but not too warm!) during this time? You need to keep the milk and starter mixture at a temperature of around 110°F for about six hours (it needs to get to a custard consistency; additional time will increase the tartness of the yogurt). Methods for doing this range from a simple thermos to a special appliance specific to yogurt making. Many cooks seem to like wrapping their pot with a towel (sometimes placed in a warmed oven, sometimes with the oven light left on), but that is too high-variable for me. For those with an oven that can be set to very low temperatures, you can get stricter consistency but then you have to accept the energy loss. After trying several of these options, I've settled on the "hot water in a cooler" method I first read about here. I have found it to be both simple and reliable.
How much whey will you strain out? I let my yogurt strain for two hours, which resulted in six cups of thick yogurt comparable to commercial brands and two cups of whey.
There are commercial Greek yogurt brands for sale on supermarket shelves laced with thickeners and other add-ins, but there are also options available which contain only milk and live cultures, so making your own to avoid such things is not strictly necessary. Taste, depending on what you're after, may be a consideration for you, but really it seems that the cost savings is the biggest issue in the DIY vs. buy final analysis.
Having grab-and-go portions of yogurt is important in our household, so once the yogurt was strained, I packaged it into 1/2-pint mason jars (though I stopped short of cutting little rounds of parchment to place on top, à la Fage). Even if homemade yogurt is made with an admittedly pricey local dairy's milk (1/2 gallon for $4 at the Baltimore farmers market, for example) it's still cheaper to make it: If you include the purchase of a starter cup of the most expensive Greek yogurt ($1.49), that amount produces six cups of strained Greek yogurt for $5.49 vs $8.94 for six slightly smaller individual store-bought six-ounce cups of Fage.
The savings increase dramatically from here, even if you purchase commercial yogurt in the largest portion possible. A gallon of organic whole milk at the grocery retails locally for $5.69, non-organic for $2.99. Based on my calculations, that means the per-ounce price breaks down like this.
- Fage: $0.17/ounce
- House brand Greek yogurt (no additives): $0.13/ounce
- Farmers market milk: $0.08/ounce
- House brand milk, organic: $0.06/ounce
- House brand milk, non-organic: $0.03/ounce
I did not include the cost of the starter here, since once you get going, you will only need to replace the starter if yours begins to weaken. You'll need to factor in the cost of your own labor and energy usage over and above these figures when evaluating your options.