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Most sourdough instructions warn not to overextend primary fermentation, as doing so will exhaust the yeast's food supply for proving after shaping. Standard sourdough recipes call for a 3-4 hour bulk fermentation stage.

How, then, does no-knead bread not exhaust its food supply when such recipes call for more vigorous yeast variants than a sourdough starter (e.g. instant/active dry yeast) along with a 24 hour bulk fermentation?

Note: Chad Robertson's Tartine Bread notes that glutens in the dough begin degrading after a certain point due to increasing acidity. Perhaps this is an additional factor that separates the two methods, as the no-knead bread doesn't have an acid-laden levain to contend with?

References

No-knead bread:

Sourdough bread:

  • Chad Robertson's Tartine Bread Country Loaf (3-4 hour bulk fermentation)
  • Ken Forkish's Flour Water Salt Yeast Double-Fed Sweet Levain Bread (5 hour bulk fermentation)
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    Have you looked at the temperatures where the fermentation/proofing takes place?
    – GdD
    Apr 6 at 8:24
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    And have you checked the amount of yeast going in those recipes?
    – Stephie
    Apr 6 at 13:53
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    I'm gonna disagree with "standard sourdough recipes call for 3-4 hour fermentation". I have a lot of sourdough recipes, most of them are 6 to 18 hours. I think you're being decieved because those sourdough recipes divide up fermentation into several stages.
    – FuzzyChef
    Apr 6 at 17:00
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    For example, the Tartine sourdough recipe starts with a nine-hour preferment, making its total fermentation time 13-14 hours.
    – FuzzyChef
    Apr 6 at 17:04
  • Thank you all for the comments. @ GdD The fermentation takes place at "room temperature" for all the recipes, but I can see how that would play a role. @ Stephie I'm not sure how to compare the leavening power of active dry yeast to sourdough starter, but that's a great point that quantity is probably a key factor. @ FuzzyChef thanks for pointing the division of fermentation as well. I wasn't factoring in the levain fermentation time.
    – lerner
    Apr 7 at 1:31

2 Answers 2

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This kind of rising didn't originate with the No-Knead recipe. Slow-rise breads are traditional -- more so than fast-rise breads, which are a relatively recent development in the history of bread. Slow-rise recipes are required with older methods of starting bread, including biga, poolish, sourdough, and pate fermentee.

So an 8-72 hour rise is actually "normal" and it's the crazy fast 2-hour rise that's surprising that it even works.

So how do slow rises in general avoid exhausting the dough? Via two simple methods: starting with very little yeast (as in 1g to 5g, or a dormant starter, or environmental yeast, depending on the recipe) and rising at low temperatures (8-15C). Both of these things slow down yeast growth and spread through the dough.

Probably the best way to see the math for this is the PizzApp, which is widely used by home pizza makers with Neapolitan-style pizza ovens. Since traditional pizza doughs are fermented for 12-48 hours, the app allow you to enter rising time and rising temperature, and it will give you the yeast amount. For a 24 hour dough, I've had it recommend at little as 0.25g of active dry yeast (which is challenging to measure). You can also play with it a bit and see how much ambient temperature affects the rise time.

Books for additional reference:

  • On Food and Cooking, Harold McGee
  • Six Thousand Years of Bread, Heinrich Jacob
  • White Bread, Aaron Bobrow-Strain
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    Ah, yes. The reason why I bough a jeweler’s scale. Very ironic comments from the teen and teen-at-heart members of the household ensued.
    – Stephie
    Apr 6 at 18:08
  • Thanks for the great information and resources! I will take a closer look at these.
    – lerner
    Apr 7 at 1:32
  • Stephie: I once ordered 20 migrogram scales for a class I was teaching. I'm still surprised I didn't get a visit from the FBI.
    – FuzzyChef
    Apr 7 at 23:48
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It really depends on the variety of yeast you are using, modern baker's yeast is fast acting as a pose to fresh yeast varieties or wild yeasts you germinate from a sour dough culture, versus sour dough starters you can buy. Then there is your flour if it's whole grain or mainly endosperm, higher starch means more natural sugar which effects the rise. If are interested in the topic of yeast digestion, reproduction, and the bipoducts of said processes there are a number of online and book sources.

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