Making Yogurt

Making your own yogurt is fairly easy, and can save you a LOT of money if you eat yogurt a lot.  A gallon of milk generally goes for $2.50-$3.00 around here, and makes the equivalent of about ten and a half of those little 6-oz/ yogurt cups that you buy (for probably $6-7), or two of the 32-oz. tubs (around $6).

I was first inspired to make yogurt by my 2012 intern, Megan.  Since then, a lot of other have been asking me about it, and I refer them to various blogs and online instructions that I have found.  With all of the information out there, however, everyone just asks me how I do it, what works for me.  And this is it:


First, you need to heat your milk.  I use a homemade double boiler with several inches of water in the lower pan:

If you don't have two pans that fit inside each other, you can use a metal bowl in place of the upper pan.  It it important that the two pans (or whatever you use) fit tightly together so the heat doesn't escape out the sides.  If there are large gaps, use foil to close them.  Or just heat your milk in the microwave.  Some people do the whole yogurt-making process in a crockpot, but I have never tried that, as I make a LOT of yogurt at a time.

I usually make somewhere between 1-3 gallons of yogurt at a time.  The smallest amount I have made is half a gallon.   Whole milk will make a thicker yogurt, skim milk will make a thinner yogurt; anything will work.  For this batch, I used half a gallon of whole and one gallon of 2%.  For home, I usually use skim or 1%, but for work I make it a little richer sometimes.

Heat your milk, covered, to 180 degrees.  Some people say you need to (to change the proteins in the milk to something that will solidify better), some people say you only need to heat it to 110 degrees.  Whatever the case, I heat it to 180.  Ideally, you would use a thermometer to check the temperature, but I have found that it is ready when it looks like this:

Lousy cell phone camera.  You can sort of see little bubbles on the milk.  When those little bubbles are across the whole surface of the milk, it is ready.  It is not boiling, just has little bubbles everywhere.

Next, remove the upper pan from heat, and cool it quickly to around 110 degrees.  I put mine in a sink full of cold/ice water:

If you are using as much milk as I do, you may need to stir the milk and/or change the water once or twice during the cooling process.

Once again, you would ideally have a thermometer so you would know what the milk is at 110, but if you don't, cool the milk until it is still warm, but you can hold a (clean) finger in the center of the milk comfortably.

Next, you inoculate (I love that word!) it with yogurt cultures.  I use one cup of yogurt per gallon of milk, some people use less.  Once you have made a batch of yogurt, just use some of that for your next batch.  Now, yogurt cultures do die after about two weeks, so if it has been much longer that that since you made your last batch, you might want to buy some new yogurt.

What kind of yogurt should to buy?  This is what I usually start with:

You can buy smaller single-serve yogurts also.  The important things to remember is that it needs to be plain, it needs to contain active cultures (it will say on the package somewhere), and it needs to not be past its expiration date by the time you will use it.  Some people say not to use lowfat yogurt, but I will use it as long as there aren't lots of weird ingredients like gelatin and other thickeners.  If the ingredients are basically just "milk" and "active cultures (of some sort), I will use it, whether it is nonfat, greek, all natural, or whatever.

To inoculate it, put the yogurt in a bowl and add a little of the warm milk to it.  Whisk away any lumps, then add it to the rest of the milk, whisking well.  If you used a lowfat/nonfat milk, you could add some dry milk powder to it if you want your yogurt to be a little thicker.  Some people will add gelatin, but I prefer not to.

Next, you need to incubate your yogurt.  You could leave it in the pan, you could pour it into clean glass jars, or whatever you want.  The milk now needs to stay at 110 degrees for a while to allow the little yogurt bacterias to multiply properly.  There are various ways to do this:

• many ovens will be 110 degrees just with the pilot light on.  My oven at work is like that.  But you should find out for sure with an oven thermometer.
• turn your oven on low, then turn it off.  Wrap your yogurt containers in towels (I use an old comforter when I make it at home!) and put it in the warm oven.
• wrap the containers in towels and place in a cooler.

Again, some people use crock pots for the whole process, but I have never looked into it and therefore don't know the instructions for that.  I have always used the pilot light method or the towels/oven method.

If there is any chance that someone might come in and turn on the oven without checking inside first, put up a warning sign so they will leave your yogurt alone!

The yogurt needs to incubate for at least 4 hours, or up to about 20 hours, depending on how tart you like it.  I usually leave mine for 12-16 hours.

When you take it out of the oven, the yogurt will be solid, probably with a little yellow whey on the top. 

For it to thicken the rest of the way, the yogurt needs to be thoroughly chilled.  Just chill it in whatever container you used to incubate.

After it is chilled, it is ready to eat!  You could flavor it at this point, too (vanilla and sugar, strawberry jam, honey, etc.).