Reader Hans Fugal had this to say about my assertion that sourdough bread typically has smaller holes (i.e. a “tighter crumb”):
I beg to differ. I routinely make sourdough bread with an open crumb and not a grain of commercial yeast.
The higher hydration seems to be the key, and of course it gets tricky to manage the dough with high hydration without mutilating it (and you). But if you have a light touch and high enough hydration (and a hot enough oven, but you definitely have that), you will have an open crumb, in my experience.
I generally do 70-72% hydration with something similar to the “no-knead” method. I mix, leave it out overnight (if it’s blazing hot like it is now maybe in the fridge, or the dough gets ruined), then stretch and fold in thirds each direction, let that rest 5-10 minutes, then shape and let rise then bake on a stone or (even better) in a (preheated) dutch oven.
Being as lazy as I am, I’ve tried to eliminate all the other variables, especially the ones that involve lots of intricate timing and the ones that get sticky gooey dough all over my hands. I’m pretty sure hydration and handling are the primary factors in how open the crumb is – more and less respectively if you want an open crumb. But you probably already knew that, I just wanted to counter the claim that you need to spike it with baker’s yeast.
I do find that bread with a weaker rise (e.g. sourdough) baked in a 350° oven in a bread pan will not return optimal results (though my wife likes me to do her bread that way because it makes a more sandwich-friendly loaf). It has to be in a hot oven (450°-500°+) and preferably on a stone (or brick oven floor).
As proof of my claim I offer this sourdough baguette:
This is one of those areas of bread baking where reasonable people can differ, as they say. In the bakery where I was trained, it was accepted wisdom that sourdough (or perhaps I should say “starter-heavy”) breads didn’t provide the same open crumb as those made with (or “spiked” with) commercial yeast. I don’t have any hard science to back this up, just anecdotal evidence, though it may simply have been the case that the starter-intensive recipes we worked with were drier (i.e. had less “hydration”).
My personal view is not that it’s not possible to get an open crumb using a natural starter alone, just more difficult. A variety of techniques, many of which my friend Hans employs (from dough stretching to hydration, autolyse to an extra-hot oven) can compensate for the weaker rise of naturally leavened bread. I’m simply used to adding a little commercial yeast to my final dough to get the “pop” I need.
If you’re interested, Hans has a free download of some of his favorite sourdough recipes here.