August 19, 2016 - 3:06am
Can commercial yeast take over an established sourdough starter?
I've read that one must keep the starter separate from dough that contains commercial yeast. According to that article (I can't remember exactly where I read that) - commercial yeast might take a foothold in the sourdough starter, and eventually out-compete the less vigorous native yeasts. Is this a valid concern? Can commercial yeast colonize and eventually take over the yeast population in a mature sourdough starter? My SD starter is now 2 months old, with a pronounced tang.
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should keep the commercial yeast from establishing a foothold, the wild yeast likes this environment while the commercial yeast doesn't.
Gerhard
Commercial yeast probably won't be able to take over completely your sourdough starter just from incidental airborne contact, but I would imagine that exposure to the commercial yeast could have a temporary effect on your sourdough starter, as you will be tipping the balances in favor of a single strain of yeast by its very introduction. However, with time and with more feedings (and less or no exposure to the commercial yeast), the sourdough starter will return to its native microbial diversity. I have worked with several bakers who use both sourdough and commercial yeast regularly, and there was no categorical "never the twain shall meet."
where a culture was contaminated with yest. TRhe yeast was all dead within (2) 24 hour feeding periods. Commercial yeast dant take the acid environment and are out competed by SD strains.
Even if it were true, why would that be a problem from a practical standpoint?
Well, that was reassuring indeed! I can now put that thought out of my head. I won't elaborate on it too much, since it might perpetuate the myth, but to "Suave" - I was trying to avoid contamination with commercial yeast since I had the mistaken notion that if commercial yeast takes over, it might out-compete the lactic acid bacteria, and render the culture and (and eventually, the baked bread) to be less sour. Something to do with commercial yeast and the LAB's being able to utilize a common substrate: maltose.
Well, I'm glad that won't happen - as "Dabrownman" succinctly puts it: that the commercial yeast will be dead within a couple of feeding cycles because of the acid environment.
Thank you all!