Greek yogurt is, hands down, the ‘it’ item in the dairy aisle today. Companies are now expanding their empire to include everything from Greek yogurt cream cheese to frozen Greek yogurt pops. Sadly, the price tag on these items is not as friendly as the flavor, so here are some tips and tricks to make great Greek yogurt at home, as well as an easy to follow recipe using store bought yogurt as a starter, and a little more information on what you may be buying.
If you’ve checked out the slick packaging on Greek yogurt, you’ve probably noticed many of them are labeled as ‘traditional’ or ‘authentic’. Those terms indicate the yogurt has been strained (i.e. whey expelled) to create a thicker, creamier product. Advertisers may be using those terms a bit loosely, since they are using cow’s milk and commercial cultures, but that is the primary difference between Greek and regular yogurt.
Since whey is expelled from Greek yogurt, it has a much lower yield (as much as 4 pounds of milk to make 1 pound of yogurt) than regular yogurt. That, and the cost associated with the proper disposal of such large volumes of whey (which is quite acidic), explains, at least in part, the higher cost of Greek yogurt. Whey disposal is an interesting and complicated problem companies are facing as Greek yogurt takes a larger and larger part of the market share. If you’re interested in learning more about Greek yogurt’s carbon footprint or the technology being utilized to deal with surplus whey, such as electricity producing whey digesters, NPR has several articles online.
If you have livestock, bake a lot of bread or have acid loving plants, you probably embrace whey as a by-product of cheese-making. I, however, get flashbacks to my working stay at farmstead dairy where I regularly hauled overflowing five gallon buckets filled with whey, two at a time through the summer heat. After being doused in that sticky substance enough times, I avoid it if possible. On a more intellectual note, I dislike the idea of losing the extra protein, vitamins and minerals contained in whey – why strain out the healthy parts? Besides, straining is an extra step that takes up time, space, and makes more dirty dishes. So, here’s a way to skip all that – fortify your milk. By fortifying with powdered milk you increase the milk solids such as lactose and protein available for the cultures to act on and with, without increasing the liquid volume. This cuts out the straining step, by creating a thicker product during incubation. When adding the powdered milk, try to add it slowly or sift it in to avoid grainy lumps in your finished product. This is not traditional Greek yogurt, but it will produce the same results both in texture and flavor with less waste.
For this recipe I use store bought Greek yogurt as the starter culture. Freeze dried cultures are available, and if you prefer, can be used instead by following the package’s instructions. Always, use only plain yogurt and check the ingredient list to make sure there are no preservatives, stabilizers or other fillers, and that the yogurt has live cultures. Almost all commercial Greek yogurt has the same four basic cultures: S. Thermophilus, L. Bulgaricus, L. Acidophilus and L. Casei. Hence, most brands will work equally well, but if there is a brand you prefer because it’s organic, rBST or gluten free, etc. use that. To inoculate the milk, I use a ratio of two tablespoons of yogurt for three cups of milk. You can use whatever volume of milk you like by adjusting the ratio. It’s best to bring the yogurt to room temperature before incorporating it, as this will help reduce lumps. Smooth out any lumps with your spatula as you stir. If any remain they will rise to the surface of the milk while it’s incubating, and you can skim them off before refrigeration.
After your fortified milk is at temperature (110F) and you’ve incorporated the yogurt starter, carefully transfer it to dry sterilized containers. I like to use ball jars – they’re easy to sterilize, can withstand a wide range of temperatures, and are leak proof. Rest the lids on the jars and screw the fastener on loosely during incubation. (Do not screw it all the way on!).
For yogurt to reach its final consistency and tangy taste it needs to be incubated at constant temperature for an extended time. The ideal temperature for yogurt is around 110F (I aim for +/- 2 degrees). The length of incubation will affect the thickness and flavor of the final result. Generally the yogurt will begin to set up after 6 hours, but it will be thin and very mild. I let mine incubate for 12 hours or longer – preferably overnight.
There are several easy methods for incubation – a yogurt making machine like Yogotherm, a cooler, or a crock pot (the latter two methods are basically temperature stable water baths.). For the cooler method add enough 120 degree water to come up to the neck of the yogurt containers and securely close the cooler lid. Put the cooler somewhere warm and out of the way (so it won’t get bumped). If you’re going to use a crock pot, find out what its running temperature is on low by filling it half full of water, leaving it turned on with the lid on for an hour, then checking the water temperature. Mine runs at about 125 on warm, so I heat it up then turn it off before adding my yogurt containers (again, make sure the water is not higher than the neck of your smallest container.). If yours runs closer to 110, try making a batch with it left on. Turn the pot back on warm as needed to maintain the correct temperature. In colder weather you can wrap the crock pot with a towel (cover the lid) to help retain heat. For both these methods I check the water temperature about every four hours.
How fast the water bath temperature drops is greatly affected by the ambient room temperature, so if your house is 60F, expect to check and reheat more often than if it’s 80. If the temperature drops too much your product isn’t ruined, but the cultures will slow down or stop. If that happens just bring the water back up to temp and expect to have a longer incubation time to compensate for the lost time. However, it’s important not to let the yogurt’s temperature get above 115 for any extended amount of time. It will kill the cultures and all you’ll have made is warm milk
It may be possible to hold back some of your previous batch as a mother culture for the next batch. However, if you plan on doing this I would suggest you start with a purchased culture designed for this purpose. The cultures used for commercial yogurt are not necessarily selected for their longevity or continued vigor, so as more batches are made the balance of different bacterial strains will not shift, and some may even be lost all together. Heirloom cultures (same idea as heirloom veggies) are a great option for mother cultures or to use as a normal starter culture which link us to generations of previous cheese makers.
A few other things to note… Cow’s milk can be substituted without any changes to the recipe. This recipe does not “scald” the milk (bringing it to 180F+). In most yogurt recipes scalding is basically pasteurizing the milk. If you are using raw milk and would like it pasteurized, follow regular pasteurizing instructions then let the milk cool to 110F.
Greek Yogurt Recipe
- 4 tablespoons plain Greek yogurt (no preservatives or additives)
- 6 cups milk
- ½ cup powdered milk
- Stainless steel pot
1. Let yogurt come to room temp (this makes it easier to incorporate.)
2. Add powdered milk and milk to pan. Heat to 110F over medium heat. Stir regularly to prevent scorching. Smooth out any powdered milk lumps with spoon.3. Once 110F is reached, add the yogurt and remove from heat. Try to completely incorporate the yogurt and work out any lumps.
4. Transfer to sterilized containers for incubation.
5. Maintain 110F for 6-12 hours (longer incubation creates tangier flavor). This is easiest to do in a cooler with 120 degree water added to it or in a crock pot, turn the heat on and off as needed to maintain temp. (Test the temperature of your crock pot before using. Many will run to hot, even on warm, to leave it turned on.).
6. Chill for 6 hours and enjoy!