I've heard that you have to have a starter for sourdough, but always was puzzled by "if you have to have a starter, and most people I've talked to get their starters from someone else, then how did the first starter get started?"
A Sourdough starter is made by daily attention to a slurry of liquid and a whole grain flour. (Especially including bran and germ)
I'm in the SouthEast of the USA....
Meaning that they are more fussy than in other parts of the USA. Usually the Great Lakes areas, The West Coast, and up into the New England areas Usually have the best luck with these. They tend to be stable and don't have shifts of bacteria strains fighting for dominance.
It probably will take as long as a human person to get this starter to be mature. Yes, 17 years.
There's a war going on in my starter....it's a blend of bacteria all fighting for dominance. Wild yeast and other bacteria such as lactobaccilli fighting to be dominant.
I want the lactobaccilli to win. These bacteria produce gas (for leavening), lactic acid and acetic acid for the flavor.
These bacteria are in the air and the whole grain flour which includes the bran and germ.
To give the lactobaccilli a better chance I have used pineapple juice to make the environment acidic. And for the next few days I'm going to continue that practice.
Pineapple juice contains sugars, enzymes and acids that the harmful bacteria have a difficult time growing in. The lactobaccilli do not. They love this environment.
Next week I need to wean them off the sugar so they won't get the pineapple juice anymore...just water.
I started mine with rye....but I am going to use some whole wheat in a while.
Mature Sourdough starters can be fed with white refined flour....but also stale bread(make sure it is NOT moldy), onions, potato peelings and all sorts of vegetable matter. Vegetables need to be processed first....but they will feed a starter well.
What a Sourdough starter is fed is usually something of a proprietary secret. Each Sourdough starter is unique and provides a unique flavor.
Once a starter is somewhat mature....it can be used daily on camping trips as it needs no refrigeration. Also if your starter seems to be doing well....take a cup or two and freeze it instead of throwing it out. Because if it goes bad or dies ...you now have a backup plan that will work in 24 hours.
Otherwise it's a 2 month process to get a starter (levain) that is mature enough to make a great loaf of bread.