I’ve been recently trying to make a sourdough starter at home and I’ve got a couple of factual questions about sourdough bread:
I got the impression from Michael Pollan’s Cooked on Netflix that prior to the mid-19th century, all bread was sourdough. To what extent is this true?
I know there weren’t commercial baker’s yeasts, but were all bread products sour like San Francisco sourdough is today, or were there ways to make bread with wild yeast that didn’t have as much lactobacteria? To what extent did bread baked in different regions taste different (based on the yeast culture rather than the skill of the baker)? Which leads me to my second question:
I’ve heard that making a starter from scratch causes your local yeasts and bacteria to grow and create a unique flavor associated with your particular region. That you’re “capturing” wild yeast and bacteria from the air where you made the starter. On the other hand, I’ve heard that the yeast and bacteria actually come from the flour itself, and you’re not really capturing anything from the local atmosphere. Which of these is closer to the truth?
And what if I use a starter from somewhere else? For example, you can buy “authentic” sourdough starters from San Francisco over the internet. If I buy one and nurture it, after a few rounds of disposing half of it and feeding it with fresh flour and water, how much of the original San Francisco yeast/bacteria are left? Have I made a culture of San Francisco yeasts, or a culture of my local yeasts just with some help from the San Francisco yeast to get started? Or have I cultivated yeasts from wherever the flour I used to feed it was grown or milled?
Either a mother dough or barm (the foam from the top of beer brewing) was used to provide the yeast. A mother dough starter would have been more like a sourdough when made, and barm more similar to a modern loaf, though the yeast used in brewing today, and what we use for baking are very different.
Adjusting the level of hydration of your starter can influence the type of lactobacteria present. Low hydration leans more to acetic (vinegar) flavors, and higher hydration more towards yogurt type sour. Adjusting rise times and temperature of fermentation will radically change the sour level of a loaf.
I’m of the “yeasts and bacteria come from your flour” school. While your local environment will certainly contribute wild microflora from utensils, water, and the air, the largest source will be from your flour.
It’d start as a pure culture, but over time will become something unique, unless you’re in SF and using the same flour. That’s part of the fun of sourdough though, you end up with a product that is uniquely your own.