We used to buy plain Greek yogurt from Costco to keep up with the demand, until several years ago, when I learned how to make it myself. My first recipes for yogurt involved using combinations of different kinds of milk: powdered, fat-free and 2%. Over time, I have simplified my recipe to what is below. Honestly, it is going to look very complicated, but it is truly a simple process. It does not require crazy unitaskers like yogurt warmers. I will summarize the process before jumping into details with pictures. Hopefully, this approach will not scare you off, dear reader.
Quick summaryIn a slow-cooker, add 8 cups of milk and set it on high. When the milk heats up to 180° (which will take about 2 hours), cool it down to 115°. Mix into the cooled milk 1/2 C of yogurt from a previous batch. Keep the mixture at about 100° for 6-8 hours. Done. You have yogurt at the cost of milk.
To make Greek yogurt, just strain the yogurt through a cloth for an hour or two to allow the whey to drip away. Stop straining when the yogurt is as thick as you want it to be. Done. You have Greek yogurt at the cost of, well, nothing.
- Slow cooker. The smaller models, which hold about 2 quarts, are best.
- Oven with a light
Detailed / Photographic Plan
- Turn on the light in your oven.
I'll explain later. Trust me.
- Measure 1/2 cup (100g) of starter yogurt into a large container.
You need some good yogurt to get the process going. If this is your first time, then go buy a small container of yogurt, but make sure it says it contains live & active yogurt cultures.
- Measure 8 cups of milk into a slow cooker.
- Heat the milk to 180°.
Set your cooker to high.
This recipe is really a process of culturing bacteria. We want to make a safe & sterile home for the bacteria we want, in this case called Lactobacillus bulgaricus and Streptococcus thermophilus. These live in your starter yogurt. By heating the milk to 180°, effectively sterilize the milk. This takes me just over 2 hours.
- Cool the milk to 105° - 115°.
Now that the milk is mostly sterile & clean, we have to cool the milk down to a temperature range that supports life -- the life in your starter yogurt.
Using 2 metal bowls, fill a large bowl with cold tap water. Pour the hot milk into a smaller metal bowl and have it float in the water. Since the metal is a great conductor, the temperature reduces to the safe zone in about 8 minutes. You want the milk to be between 105° and 115°.
- Mix the cooled milk and starter yogurt.
Pour a little of the cooled milk into your starter yogurt to loosen it up first. Add enough milk and mix it up until it becomes fluid and will flow easily. Simply pour the loosened starter mixture back into the small metal bowl holding the cooled milk and mix thoroughly.
- Move the milk mixture (yogurt & milk) to a warm 100° resting area.
We're almost finished. This part takes the longest amount of time.
Pour the milk & yogurt mixture back into the crock that was used to heat my milk, put the lid on it and cover it with a towel. Place this little setup into your oven that has had its light on since step 1. The oven body is should be around 100°. This is a wonderfully warm temperature for bacteria where they will live and prosper and multiple and multiple and multiple.
After about 8 hours, the milk will have so many Lactobacillus bulgaricus and Streptococcus thermophilus (that's yogurt, remember?) that it will become thick and gelatinous.
- Cool the new yogurt.
At this point, you are finished. You have yogurt, albeit, warm yogurt. You could move the yogurt to containers and store in the refrigerator.
For me, I take the crock out of the oven and move it straight to the refrigerator. Since I usually make yogurt 3 or 4 nights in a row to build up a supply, I'll wait until the evening to empty the crock.
- Make Greek yogurt.
Greek yogurt is simply yogurt that has been strained to remove whey -- a high protein liquid.
Lay a cloth napkin over the top of a tall container and secure it in place with a rubber band. Push down on the napkin to create a large pocket to hold the yogurt. Thoroughly whisk the yogurt before pouring it into the strainer. This will break up the yogurt and speed up the straining process. Depending on the thickness of your cloth, the whey will stream through it and into the container. I strain the yogurt for just over 2 hours.
Personally, I haven't found a fantastic use for the whey yet. When I do, I'll post here. Leave a comment for your fantastic uses of yogurt whey.
- Repeat the whole process.
First batch is finished. I'm lazy & I don't want to wash the crock, since I make yogurt several nights in a row, I follow a simple pattern. I start at 9 pm, so the yogurt is in the warm oven at about 11:30 pm. I pull it out at 8 am the next morning where it goes into the refrigerator while I'm at work. At 9 pm, I start straining the new yogurt while I make the next batch. That means, step 9 and step 1 are happening simultaneously.