I'm putting "sourdough" in quotes because it's such an imprecise term.... And though I'm not sure this is quite the right place to post this, well, I couldn't figure out where it might go exactly.
Anyway, to preface the topic I'm raising here (with a link below),... when I talk to new customers or other folks face to face about what I do, inevitably I have to start with the more common and more universal terminology which is to say that I make wood-fired sourdoughs. But then immediately, I go on to correct what are bound to be misperceptions about what a sourdough bread is.
Sourdough doesn't mean "sour." Or not necessarily. And in fact, for most artisan bakers if your culture is "sour," you're probably doing something wrong. For most of us who work within the artisan bread genre, what we do is more precisely called "naturally-leavened" breads. But because the leaven we use is generally and universally called a sourdough culture, and because it's so universally understood by people everywhere by that term, we lapse back into it ourselves because it's simpler to be understood right off the bat, even though it's not exactly correct.
So here.... A sourdough culture is simply flour (of one type or another) and water. It's a natural yeast. A natural leaven. To get to the point where it may be used to leaven bread, it needs to be suspended over time in a more or less constant state of fermentation. Which simply means you add more flour and water and let it sit somewhere til it begins to bubble and rise.
Unfortunately, almost every grocery store carries faux "sourdoughs" which people often mistake for the real thing. Those breads are fake sourdoughs, and they are simply junk bread with a chemical additive thrown in to mimic "sour," and which, frankly, to me anyway, smells like stinky sneakers. Don't buy that. It's crap. It's what gives "sourdough" a bad name. There's nothing authentic about that bread.
So, I'd like to see the term "sourdough" retired. The more apt term is actually "naturally-leavened." And if you refresh your culture frequently, what you'll have is a lovely, soft, bready/mildly-yeasty smelling culture. Nothing sharp or sour. Many folks who make sourdough breads at home, and especially folks who make them infrequently, taking their culture out of the fridge and refreshing only occasionally, will in fact probably end up with a "sour" sourdough bread. And that's exactly what you'll have if you refresh your culture infrequently. Artisan bakers who bake every day, however, or frequently, refresh their cultures once, twice and even three times a day, and so their cultures are usually a lovely, soft and fairly mild culture. Taste it, if you make your own. It should taste soft and lovely, not sour. One artisan baker I know refreshes three times a day, another once, and I generally refresh mine twice leading up to a bake.
That's a maybe tedious primer on the process, which leads to the actual thing I wanted to raise here, which is the relative health benefits of "sourdough" or naturally-leavened breads, which fall in the category of "fermented" foods and which have particular properties which distinguish them from breads using commercial yeasts.
There's a whole school of science on the health benefits of the fermentation process in foods (see Weston Price or Sally Fallon), and although the generally-accepted school of thought insists it's whole wheat flours which confer the greatest health benefits, as opposed to white or all-purpose flour, the scientific evidence suggests the fermentation in itself (or "sourdough," or natural leaven) trumps the issue of flours altogether. It's the fermentation, acting on blood sugars and insulin levels, not the type of flour, that confers the better health benefits.
For an interesting read on the relative health benefits of naturally-leavened breads, here's a link: http://www.bakersjournal.com/index.php? ... ew&id=1245
And when you buy a "sourdough" loaf, ask for better clarification about what exactly goes into that loaf, because even breads billed as "artisan sourdough" are too often produced with commercial yeast in addition to the sourdough culture, which many bakers fail to divulge.