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Comment by lapetitejort | Hacker News Reader

I had a revelation recently regarding commercial dry yeast and poolish. The sour part of sourdough comes from the lactobacillus bacteria making lactic acid. Commercial dry yeast makes for a fast rise, which isn't enough time for the minuscule amount of bacteria that's present in the flour to flourish (pun intended?). Letting the mixture ferment overnight lets the bacteria grow more, which creates the flavor. My guess is this technique can be used to stand up a sourdough starter from scratch faster than mixing raw flour with water over the course of a week or so.

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This revelation is usually in the introduction or first chapter of any book covering sourdough specifically or fermentation generally. But yes pretty much correct. Acetic acid bacteria are also a factor.

Anyway though, the long fermentation probably does give some chance for the bacteria to develop but it's not the main flavoring factor on that time scale. It's just esters from the alcohol and enzyme byproducts and shit idk I'm not a chemist. You can pasteurize your flour before adding yeast to prove it though, it's an uncommon but known cooking school demo.

It either does or doesn't work for speed running a sourdough starter depending on what your goal is. If you want a workable starter to bake with it will be super fast, but the bread is indistinguishable from one baked from a poolish with commercial yeast. Which is basically what you're doing. If you want any of the flavor or texture indicators of sourdough they wont be there in that time frame though, since you won't have enough bacteria.

Over time it will drift towards standard starters and after weeks or months will be indistinguishable from them.

Don't forget to use the parachute when getting off your high horse.

I mean you purported to add to the knowledge base of a domain older than written language without doing the absolute minimum engagement with the earned knowledge of that domain. Who is really lacking humility here lol.

You are pissing on the wrong person.

But even regardless of that, lapetitjort was sharing something that they realized themselves. No need to be a dismissive ass, even if it concerns the use of commercial dry yeast that is somehow older than written language.

The benefit of poolish and other styles of pre-ferment is usually attributed to enzymatic breakdown of proteins and starches (especially of starch into dextrins and maltose, which benefits the color of baked bread as well). An overnight ferment probably isn't long enough to get a substantial bacterial population going, hence the multi-day or week process of creating a sourdough starter. Why would the addition of commercial yeast speed the bacteria along?

I'll preface that I'm a beginner and not a food scientist in any right. I tried to make a starter twice and failed both times. I can't say for certain why, but it could have been from impatience not seeing the start rise every day while the colonies built up. If I were to see the starter rise due to yeast action, I would be more likely to maintain it, which would give the bacteria more time to create a colony. So it's not speeding the bacteria along, but rather "faking it until you make it".

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