Hey Danubian, JohnD, and others...
I didn't want to take up Della's space on molds, but you guys were actually getting into very detailed stuff about sourdough...especially right down to the microbiology of it. I'm just wondering if you guys actually started out as biologists turned bakers or what? Or did you actually studied this stuff on your own? When I was in baking class we did skimmed the microbiology of sourdough and yeast very lightly. Just curious.
I didn't want to take up Della's space on molds, but you guys were actually getting into very detailed stuff about sourdough...especially right down to the microbiology of it. I'm just wondering if you guys actually started out as biologists turned bakers or what? Or did you actually studied this stuff on your own? When I was in baking class we did skimmed the microbiology of sourdough and yeast very lightly. Just curious.
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Thanks, doughman, for starting one which deserves its own topic title.
From what I understand about the contamination bit, isn't it that baker's yeast aren't able to survive in sourdough cultures mostly because other, more well-adapted critters as well as s.c. itself, produce end products that don't favour s.c.'s survival as time goes by?
So the only issue I could see is if there is immediate contamination, whereby the s.c. grows rapidly in the final sourdough bread dough which is baked off hence resulting in a mostly s.c. leavened bread that has no 'sourdough characteristics'.
However, it would seem more likely that the existing microbes in the sourdough dough would have an advantage in this case since they've already adapted long ago. The final dough is after all, slightly acidified even when the dough is initially mixed. If contamination were to happen I would think that would be the best opportunity for s.c. to come in when the dough is still 'fresh'.
But while yeast are everywhere in the environment, they do need to first land on it, adapt to the matrix, then have the proper conditions around it to multiply (substrate, pH) as well as be given enough time in order to colonize the dough properly. That again, gives the sourdough microbes a head start because they are already in dough from the onset and have started multiplying. You would probably need a threshold amount of yeast cells that fall onto the dough for it to be able to compete with sourdough microbes right from the start.
A more likely case if there was contamination could be the actual mixing phase in the mixers. If you alternate between sourdough dough and yeasted dough and don't clean it out properly there could possibly be contamination there right?
While it's definitely possible that s.c. might contaminate a sourdough bread dough, the probability that it does I think would still be pretty slim. And the chances that a sourdough culture could be taken over by baker's yeast is even more unlikely. Yes, maybe the yeast could adapt somehow, but then again we bred them so that they are monoculture and have less chances of surviving in conditions outside of the ones they are comfortable with. That's what we did to our domesticated animals, food crops etc.