Later today I am guest-lecturing for Dr. Don Pfister’s Harvard College mycology class, one I took myself back when I was one of his graduate students. He asked me to speak to the class about the Quarantinystarter project, sourdough starters, and sourdough microbiology. Seeing as I had to brush up on the details around all that stuff for the lecture, I figured now would be a good time to also write something up for all of you. Apologies in advance for the technical nature of this post, but there’s no way to further simplify what is a complex subject (and trust me, what follows is actually a
I really appreciate this in-depth explanation of what's actually going on with the sourdough culture! I do have an extremely silly, perhaps nitpicky question: A lot of bakers/recipe developers will refer to their sourdough loaves as "naturally leavened." I understand this is to distinguish that there is no added commercial yeast in the loaves, but my semantic side takes over and wonders what about a yeast-raised loaf is not "natural"?
Megan - you are right, there's nothing at all unnatural about yeast, even though it is commercially produced. My take is that one reason people choose to use that term because the English alternative, sourdough, implies the bread has to have a sour flavor, which it really does not. The other reason is our bias against human-made things in favor of "natural" ones. This happens all the time in the world of chemistry and nutrition. Cyanide is "natural" too, but that doesn't make it any less deadly a poision. And humans are as much a part of nature as any other element.
At least the moniker of naturally leavened isn't as frustrating as when items are described as "chef-inspired" or "flavor inspired" ...as you can see, sometimes my love of food clashes with my love of language.
Just double checking... I've always heard that as a rough rule of thumb, drier sourdough doughs favor acetic acid production, and higher hydration favors lactic. Your post says the opposite. Was that a typo, or do you stand by that?
I really appreciate this in-depth explanation of what's actually going on with the sourdough culture! I do have an extremely silly, perhaps nitpicky question: A lot of bakers/recipe developers will refer to their sourdough loaves as "naturally leavened." I understand this is to distinguish that there is no added commercial yeast in the loaves, but my semantic side takes over and wonders what about a yeast-raised loaf is not "natural"?
Megan - you are right, there's nothing at all unnatural about yeast, even though it is commercially produced. My take is that one reason people choose to use that term because the English alternative, sourdough, implies the bread has to have a sour flavor, which it really does not. The other reason is our bias against human-made things in favor of "natural" ones. This happens all the time in the world of chemistry and nutrition. Cyanide is "natural" too, but that doesn't make it any less deadly a poision. And humans are as much a part of nature as any other element.
Thank you!
At least the moniker of naturally leavened isn't as frustrating as when items are described as "chef-inspired" or "flavor inspired" ...as you can see, sometimes my love of food clashes with my love of language.
Great stuff!
Just double checking... I've always heard that as a rough rule of thumb, drier sourdough doughs favor acetic acid production, and higher hydration favors lactic. Your post says the opposite. Was that a typo, or do you stand by that?
Thanks,
Allen
Allen - good catch, I meant it's the other way around. Corrected!