Does starter happen because of stuff in the air or in the flour?

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brianlaz on

 

I always thought it was about the air, and that's why San Francisco sourdough is a thing--it's because only they have that air.  But I've also heard everything you need is already in the flour itself.  By "heard" I mean on a King Arthur video (I feel like they're reputable!) a guy says everything is in the flour.  Most other places I look say it's in the air.  Is it both?

Thanks, I look forward to any insight.

You need exists on the grain you use. The closer to unprocessed, the better. That’s while wholegrain flours generally work better than bleached all purpose flour. 

This question fascinates me.  How did L sanfranciscensis come to be found in sourdough cultures around the world?  For a strain to become global in that way, it must be able to survive outside the bread-making process, it must have a way of being transported in a viable state from one place to another.  I found a literature review on the internet that suggests insects as the most likely vector, which infect the flour or grain in storage (so it isn't in the grain in the field) but that doesn't seem to have been proven:

https://onlinelibrary.wiley.com/doi/10.1111/1541-4337.12459 (under the heading "Prevalence of L. sanfranciscensis in Sourdough")

It is not clear to me if these strains can propagate in the absence of bread-making, or whether they have become dependent on us humans, in which case the relationship between them and us could be called a symbiotic one.

While you are here Debra, I would like to say how informative I have found your previous posts, they have really helped me make sense of the diverse practical advice available.  And your pineapple juice starter method worked a treat for me first time!

TIM

 

"How did L sanfranciscensis come to be found in sourdough cultures around the world?  For a strain to become global in that way..."

Because it didn't start in San Francisco. That's just the name!

While occurring later but independently in Italy L. sanfranciscensis was identified as L. brevis subsp. lindneri - a subspecies of of L. brevis, which has been known of since the late 1800s to early 1900s or so.

EDIT: linderni corrected to lindneri

Indeed, but the issue that interests me is the mechanism of the spread from wherever it started - a species must originate somewhere (if you subscribe to the theory of evolution) and then spread to become worldwide.  It is unlikely that the same thing evolved independently in many different places (apparently strains of L sanfranciscensis  from around the world are very similar genetically) and its spread appears to have happened centuries ago.  Humans spread from Africa on foot, microbes need something to transport them.  A species that is only found in bakeries and flour mills, and on bakers and millers (probably) but is the same throughout the world, must have some means of transfer between places.  Human to human transmission is one possibility, but the literature reviewed in the article I linked to seems to be pointing towards fruit flies.  Of course, that is historical, in modern times bread and bakers travel widely, and cultures are available commercially, so there may be different mechanisms at play.

Why rule out things occurring independently? I don't think something like L. sanfranciscencis is the result of an isolated freak-occurrence. Evolution while competitive is a team effort.

Microbes are everywhere because we're all made of the same stuff, we're all carbon based life-forms and so all known life conforms to the rules of organic chemistry and the laws of physics that underpin interactions of matter and energy.

Indeed there are many vectors, insects, birds, mammals and because microbes are so small they can be carried by wind and water too. Fruit flies are a particular concern for winemakers because they are prolific carriers of acetic acid bacteria (AAB).

When wheat was harvested, ground into flour and mixed with water then bacteria (prokaryotes) and yeasts (eukaryotes) made their play for survival. If there is a carbon source and water there will inevitably be life.

In a wheat and water medium (dough) the most abundant sugar is maltose, so it makes sense that what came to be was a microbe that could metabolise this sugar.

 

This is a rich and interesting conversation, which is what I hoped for, but I'm still not sure--sounds like the yeast is on (in?) the grain, we all agree.  But does stuff in the air play any role?

 But i have read that if you do various cultures in your house like sourdough, kombucha or kimchi, that you need to keep them far apart, preferably in separate rooms, to prevent cross contamination.
As well we have had bakers that did well in one house but when they moved to a new house where there hadn’t been a lot of sourdough baking happening, they struggled with getting a starter going.
Based on that, there must be something floating in the air some of the time. This all anecdotal of course. 

Now you mention Danni it I have heard that, interesting. Maybe it is about numbers.  When you start a culture, it takes days/weeks for the microbes you want to build up, but eventually the ones that are most adapted to your growing environment come to predominate.  But they are starting from tiny numbers.  If you grow a different culture in a different environment nearby, the amount of those microbes flying around may be thousands or millions of times what there would normally be, and that may make it difficult for any culture to keep out the wrong type of microbe.  But as you say it is a rather haphazard process, I have had some that started off with no problems and some that didn't (and in the same house).

People do manage to brew beer and keep sourdough, but maybe there isn't so much of a problem with this combination.