Wild Fermentation, by Sandor Ellix Katz, 2003, Chelsea Green Publishing Company, White River Junctin, Vermont
When I realized how easy it was to make yogurt at home, I was amazed that it's taken me this long. I started making yogurt back in January, and I haven't looked back since. It saves money, I always have fresh yogurt on hand, and I don't have so many plastic containers to deal with.
Here's what you need to make 3 quarts:
- yogurt starter, which could be store-bought natural non-pasteurized, or your own from batch to batch. Look for "live active cultures" on the label. You'll need 3 tablespoons for 3 quarts.
- 3 quarts of fresh (as possible) low-fat milk. Make sure it's not "ultra pasteurized."
- 3 quart jars with sealable lids (I use regular Ball jars.)
- a food thermometer (I bought one really cheap at Tuesday Morning.)
- a heavy-bottomed pot to heat the milk in, a stock pot to boil water in.
- a warming container or system. I use a small cooler with a broken lid - no longer suitable for camping. Note: I make three quarts of yogurt at a time because that's what will fit into my container. Adjust this recipe to your own system.
Procedure - this is my system:
Part One: Turn on your oven to 250; I take out my top rack. Heat a gallon of water in a stock pot along with the jars and lids until boiling. Simultaneously begin heating the milk on medium. Stir the milk frequently so that less of a film will develop on the bottom of the pan and it won't scorch. Get your container ready - in a stable location (I put it in the sink.) Put the yogurt starter out so that it's not cold.
When the water boils, put the jars and lids into the container and pour the rest of the hot water in; close the lid. This will heat the container. Turn off the oven but don't open the oven door.
Heat the milk until it reaches 180 F. Then turn off the burner and let the milk cool.
Part Two: Cool the milk to 110 F. Mix the yogurt starter in. Don't be harsh with your mixing - these are live cultures looking for a new home.
Pour the hot water out of the container and jars. Fill the jars with the milk / yogurt and seal with lids. Place the jars in the warming container. Put the container in the warmish oven.
Part Three: Leave the yogurt alone for at least 8 hours; overnight is fine. Don't jostle it around - those microbes are busy. Put a note on the oven to remind the household not to turn it on (yowch - that would be a mess.)
If the yogurt has not developed it's culture (firmed up) after 8 or so hours, gently stir in another tablespoon of starter per quart, make sure it's warm, and leave it. This has not happened to me.
As you can see, it's all about maintaining a temperature that encourages the cultures to grow. As it gets warmer here in Dallas in the coming months, I'll experiment with leaving the jars out in warm areas of my house. Microbes are like all other living organisms - they have a relatively narrow range of temperature at which they're active, let alone alive. My finished yogurt is in the photo at the top of this post - refrigerate and enjoy!