Making Yogurt with Powdered Milk

Making yogurt with powdered milk is easy to do and very inexpensive.  It costs me less than $.35 to make a quart of plain yogurt and it costs me over $2.00 a quart to buy it at the store.  This is one way that I rotate through our powdered milk storage.  It is completely fat-free and I can use it as a sour cream and cream cheese substitute in my baking.  Many, many people have tried the smoothies I make with it and they can never tell it is 100% powdered milk!

Begin by mixing your powdered milk according to directions in hot tap water. I actually only add 3 cups of water to my blender so I don't make a mess and then I add the final cup of water to my bowl later. I have always used the non-instant powdered milk you can get at the LDS cannery.  (Morning Moo variety of milk will not turn into yogurt.  It is not true milk so will not culture correctly.)

Allow the milk to sit in the blender a few minutes so the foam can rise to the top.  If you look closely, you can see a line where the milk stops and foam begins.

Slowly pour the milk out of the blender into a glass bowl.  The milk will pour out and the foam will stay behind. Add any extra water at this time.

You'll need an instant read thermometer.  Be sure to test your thermometer before using to make sure it registers 212° F in boiling water.  If it is off, you will need to adjust accordingly.

Microwave the milk until it reaches 180° F.  It takes about 7 minutes in my microwave depending on how hot my tap water was. (Note added 3/2014: I have since learned that you only need to heat it to 180° F if you are using fresh milk from the cow. This pasteurizes the milk and makes it ready to turn into yogurt. All powdered milk has been pasteurized already so you only need to heat the milk to 125° F and then you can mix your plain yogurt start in right away.)

Allow to sit on the counter and cool back down to about 125° F.  This takes about 20-25 minutes so I set a timer to help me not forget about it.

Once it reaches 125° F, stir in a little plain yogurt with live cultures to use as a start.  You can use store bought yogurt or some of your own homemade yogurt once you have some.

I used homemade yogurt for my start.

Whisk it in well.

Pour into a thermos and close the lid.  Allow to sit on your counter for 4-12 hours.  The longer it sits, the tangier it is.  We prefer our yogurt not as sour tasting so I open it up in 4-5 hours.  You should have what appears to be thick milk.  Sometimes you see a little clear, yellowish whey on top.  Refrigerate when it is done. If I open my thermos and find my yogurt runnier than I want, I test the temperature. If it has dropped below 100° F, I pour the yogurt into a microwave safe container and heat it for 30 seconds to a minute. It usually instantly thickens when I do this and then I can cover it and put it right into the fridge. 

Here are the instructions one more time.  I list some troubleshooting ideas at the bottom.

Homemade Yogurt

Reconstitute powdered milk to make 1 quart. (Do not use the "Morning Moo" brand. It will not turn into yogurt.) Heat milk to 180° F stirring constantly, if heating on the stove. You can also heat the milk in the microwave. It takes me about 7 minutes in my microwave. (Note added 3/2014: You really only need to heat the reconstituted powdered milk to 120–125° F since it has been pasteurized already. This ends up saving a good amount of time and it works every time for me.) Remove from heat and let cool until milk reaches 120–125° F. Set a timer for about 20 minutes so you don't forget about it. Use an instant read food thermometer to measure the temperature. Mix in ¼–½ cup of plain yogurt with active cultures. Stir with a wire whisk. Pour into a thermos and screw on the lid. Allow to incubate for 2 ½–12 hours on your counter. I've found that when I use plain yogurt from the store it takes 4+ hours to set up. If I use my homemade yogurt as a start, it is often done in 2 ½–3 hours. The longer you incubate the yogurt, the tangier it will be. You know it is done when you open your thermos and you see a small amount of clear, yellowish liquid (whey) on the top and thick white yogurt below. If you still see milk, it needs to incubate longer. Quickly close the thermos so you don't lose much heat and let it sit another hour or more before checking again. Refrigerate after incubating. It will thicken a little more as it cools.

If you have problems having success, it is one of two things. Either your thermometer is off or your thermos does not hold the temperature at 120° F. You can test your thermometer by putting it in boiling water. It should register 212° F. If your thermometer is on, then you can assume it is your thermos and you'll have to try with another one. There are other methods for incubating yogurt. A quick search online will lead you to some articles describing the other methods. The thermos method has always worked for me, it is the least costly, and it requires less steps so it is my method of choice.