Thirteen years ago, unbeknownst to me, I made my first batch of Greek yogurt. The recipe came from an Indian cook book, which called it yogurt cheese. I used it as a substitute for cream cheese.
A few years ago, I began seeing Greek yogurt in every store. Now, it may be more popular than ordinary yogurt. It is important to read the ingredients on store bought varieties. I was horrified to discover that some companies simply thicken ordinary yogurt with corn starch or gelatin and pass it off as Greek yogurt. Real Greek yogurt should contain only milk and cultures.
It is very easy to make homemade yogurt from scratch for a fraction of the cost of commercial varieties. Greek yogurt is simply strained yogurt. There are many tutorials on the web about making yogurt. I have tried many of them below is the one that I have found the most simple and effective.
I always make yogurt in one gallon batches because I have a large family. When it is strained it is reduced to between 2 and 3 quarts of Greek yogurt. If you are unable to consume that much in less than 2 weeks the yogurt can be frozen or feel free to cut the recipe in half.
First pour 1 gallon milk of milk into a large crock pot, fresh from the cow (or goat) is best, Otherwise use minimally pasteurized non-homogenized milk. Most methods recommend pre-scalding (re-pasteurizing) the milk, but I have found this unnecessary.
Turn the crock pot on low and check the temperature of the milk every 30 minutes until it reaches the target temperature of 110 to 115 degrees Fahrenheit. When it reaches the target temperature add ½ cup plain yogurt. Maintain the target temperature for at least 4 hours and up to overnight. I unplug the crockpot, wrap the whole thing in a towel, and put it by a heater vent or the warmest spot in the house.
To make Greek yogurt; line a large colander with cheese cloth, place the colander over a large bowl, and pour your homemade yogurt or commercial plain yogurt into the colander. The whey will drip through the colander and the yogurt will thicken. Leave the yogurt for at least 4 to 8 hours (the longer it strains the thicker it will become). The finished yogurt can be stored in a mason jar for up to 2 weeks.
Be sure to use the whey for another purpose. See my post for sandwich bread made with whey.