Making and Straining Yogurt

We've been eating a lot of yogurt lately, so I decided I would start to make it myself.  This way I would know exactly where the milk came from (our dairy), and I wouldn't have to pay the high prices for the thick, Greek style yogurt I like.  

The process is very easy actually, and just takes a bit of time, and some trial and error, (in my case).  Hopefully I've made all the errors for you.  

All you need is some milk (whole or skim or anything in between),  and some yogurt with live active cultures in it.  I guess some yogurt might have more active cultures than others, so you may have to test this out yourself.  I've had success with Stonyfield Farms and Brown Cow, and maybe a couple others, I don't remember.  Now I just use my own yogurt if I have the presence of mind not to eat it all.  

You can make it in any quantity you want.  The batch in the pictures is a half a gallon of skim milk.  I use about two tablespoons of yogurt for that much milk, but I may be using more than necessary.  Better safe than sorry.  

Heat up your milk to just short of boiling, (the book I use says 180 degrees F but I've boiled it before and it works just fine.)   Take it off the burner and let it cool down (according to the book, to 116 deg F).  About 20-30 minutes.  

While milk is cooling turn the oven on to the lowest setting, (mine is 170 but anything over 120 should be fine).  Whisk your yogurt in a small bowl.  

When your milk is between 115 and 135 deg F, whisk some of it into your yogurt.  This is where I've screwed it up before... I've killed my cultures by adding them to milk that was too hot.  They curdled pretty obviously though so I think you'll know if it happens to you.  Then mix your cultures back into the rest of the milk.  I do all of this in a glass or ceramic bowl with a well fitting lid.  

Put the lid on, and stick it in the warm oven.  Turn OFF the oven.  I turn the light on for a bit more heat.  

Let it sit for four hours.  Check it, and if it's still very milky, let it sit for another hour or two.  

You have yogurt!  (sorry I don't have a pic of the plain yogurt done.)

The longer you let it sit the tangier it gets.  I've let it sit over night... I've even added more cultures to milk I'd already let sit over night, (I guess I'd killed the first cultures and didn't know it!)  

Once it's set, you can stick it in the fridge.  If it stays warm the cultures just keep multiplying and it gets even tangier.  If the whey separates just stir it back in.  

Now if you want to strain it, no big deal!  Get a couple of layers of cheese cloth, (or in my case surgical grade gauze), and lay it in a strainer.  Spoon your cold yogurt into it and tie up the ends.  I did this from my kitchen faucet the first couple times, but then my husband was kind enough to place a hook underneath one of my cabinets for this purpose.  Allow the whey to drip from the yogurt as the pressure squeezes it out.  Deppending on how thick you want it you can let this sit for hours.  I put a bowl underneath because the whey can be tasty in recipes instead of water or milk, (pizza dough, pancakes, smoothies).  Or, if you're not baking feed it to your plants.  

Here's the final product after four hours and a bit of extra squeezing... I use this stuff instead of sour cream on burritos!  And it's very high in protein.  And yes... this was made with skim milk!