Recently I made a research about how steam works in baking. I found four main functions:

  • Steam condenses and keeps the dough surface cool, preventing the crust to form too soon, what could hinder the oven spring.

  • As the water condenses, it releases a lot of energy into the dough, heating it faster.

  • Because the surface is not too hot, the enzymes work longer and we get a better crust.

  • The combination of heat + water gelates the starch and we get a crispier and shiny crust.

That makes perfect sense. Almost all of that information I got from the amazing book "On Food and Cooking", Mcgee.

Knowing that, now I am am very confused about how baking in a dutch oven works.

  • Because all the water in the environment (Dutch oven with lid on) comes from the dough. I understand that it won't condense back into the dough, so I won't get that "water layer", neither the initial "blast" of energy of the steam condensing into the dough.

Is that right? What am I missing?

My personal experience says that the Dutch oven works, I get a good oven spring and crust. But I don't know if this is because of the "humid environment" of the trapped steam as almost everybody says, or just because the dough is closer to the radiant source, so it heats faster.

By the way, do we really need to bake at that high temperature? What would happen if we could bake at 100º C (212º F) to get the oven spring and only after work on the crust color?

  • Welcome to SA! Your English is great. However, might I suggest changing the title of your question to "How does water behave in Dutch oven baking?", since that's the actual question you have? – FuzzyChef Sep 14 '20 at 20:09
  • "Condensate" is a noun, I think you meant "condense". I've proposed an edit to correct that and some other minor issues. That said, the first two points you mention seem to contradict each other. Only the second is accurate; condensation releases heat, so steam condensing isn't going to "keep the dough surface cool". It would be helpful if you could review both of those statements and make sure they express what you meant to express. – Peter Duniho Sep 14 '20 at 22:37
  • Thanks for the suggestions :) I also changed the title as you suggested, it makes more sense. I agree with you about the first two points contradicting each other, but this is exactly how is in the book "On Food and Cooking". What I think it that it reaches almost 100ºC faster, but the water layer prevents it from drying out (?). At least that is what I tough. – guistoll Sep 15 '20 at 14:57
  • Now I am reading "Modernist Bread", and it says that indeed that first point is false. I am digging deeper trying to understand it. For now everything is just so confusing. – guistoll Sep 15 '20 at 15:00
  • Why wouldn't the water condense back onto the bread? I don't see any reason for that assumption. – rumtscho Sep 15 '20 at 15:14

I think we need to deal with the two different elements of the question: first, I'll discuss better oven spring, and then I'll get to good crust formation.

Most oven spring comes from inside the bread. Air is already trapped inside the bubbles in the dough which expands as the internal temperature rises. Additional steam is released internally as the dough heats, adding to the pressure for expansion created inside the dough. The only thing necessary for good oven spring in most breads is allowing these internal gases to expand and evolve.

The main thing external steam does to impact oven spring is prevent early crust formation (as alluded to in the first point in the question). The mechanism is not only due to cooling, but due to humidity of the surrounding air. For a crust to form, the dough has to be heated above boiling temperatures. In order for the dough to get that hot, it needs to lose significant moisture (at least on the surface), effectively drying out. If a section of dough has substantial moisture, it will continue to boil out. With normal air pressure, water boils out around 212F/100C, which means that while water is boiling out of moist dough, the temperature of that portion of the dough will maintain a temperature around that boiling point.

By surrounding the dough with high moisture air, you slow the rate at which water boils out of the surface of the dough. (Water will boil out faster in a low-humidity environment compared to a high-humidity one.) So, filling your oven with steam will slow crust formation by keeping the outer layer of dough hydrated longer, which means it stays soft and doesn't harden (which would halt oven spring).

The same effect is still possible in a dutch oven, because there's a much smaller volume of air to fill with steam. A significant amount of moisture escapes bread dough while baking, and there's enough in the early phases to create a fairly moist environment inside the dutch oven, effectively simulating an oven filled with steam already. As long as a relatively high humidity environment is maintained around the dough, it will delay crust formation and aid oven spring.

The radiant heat from the dutch oven on all sides also may add to the oven spring by introducing more energy quickly into the dough. (That happens even without the condensation mechanism discussed in the question. I mean, some moisture may condense back on the cooler dough, though nowhere near as much as with an oven filled with external steam. My guess is that the condensation mechanism to deliver heat is less important for oven spring than keeping the outer layer of the dough soft and hydrated. Also, even without significant condensation, moist air will transfer heat faster than dry air.)

The previous paragraphs discuss where better oven spring comes from. The good crust formation then is also aided by the third and fourth points in the question (extended enzyme activity, which aids in ultimate browning, and starch gelation), both of which just come from the high humidity environment. In that sense, the "water layer" described in the question still can happen by simply being in a sealed container that keeps humidity relatively high.

It should be noted that most recipes for dutch oven baking state that the lid should be removed for the last portion of baking. This removes the moisture (as when a steam oven is vented during bread baking), which allows better and more consistent crust coloration as the Maillard reactions can proceed faster in a low humidity environment. Crust will still form with the lid on, but it may become somewhat thicker before it browns as much as is desired. (A lot of this depends on temperature, time of bake, hydration level, etc.) In my own experience, keeping the lid on too long can delay escape of internal moisture from the dough as well, which can sometimes give the crumb a more "gummy" texture even when fully baked.

By the way, do we really need to bake at that high temperature? What would happen if we could bake at 100º C (212º F) to get the oven spring and only after work on the crust color?

No, you do NOT have to bake at a super high temperature. In fact, some people bake successful loaves of bread starting with a cold dutch oven. See, for example, this blog post from King Arthur flour for some tips. They ultimately concluded that one should use an enclosed container with a smaller base if starting from a cold temperature. Although they don't explain why, my guess is that the long time it takes for the temperature to rise allowed a bit too much gas to escape before the bread solidified internally, leading to a slight collapse and a final loaf volume that was a bit smaller.

That said, I'd say that effect is somewhat recipe and dough dependent, as well as dependent on how long it takes for the dutch oven to heat up. It's certainly possible that in some situations a bake started with a cold dutch oven could give an equal or even superior oven spring to a loaf started in a hot oven. You're balancing two things: (1) crust formation can't happen too quickly, or the oven spring halts before the rise is complete, but (2) structure needs to set quick enough before gases migrate out of the dough, and the gluten isn't sufficient to continue to hold up the expanded dough (without the set internal structure). Starting in with a cold dutch oven avoids the first, but could cause problems with the second. If the timing is right, though, one could maximize oven spring and still get good crust formation and color at the end. However, at some point, one does need to finish with a rather hot oven to get the browning and "crackling" element of the outermost layer of crust in a lean dough.

  • I think things are clearer in my head now. Sorry for the delay, but now I am reading a new book and it says that actually the steam does NOT play a role in oven spring, this is just a myth. I am very confused right now. But your answer makes perfect sense. I am convinced that a humid environment delays crust formation, so we can get a bread with a thinner curst. But if that makes a diference in the oven spring I really cant tell. – guistoll Sep 18 '20 at 13:42
  • @guistoll: Well, I've seen multiple baking books that have shown photos of bread baked with and without steam (in professional ovens), which shows a clear difference in loaf volume. So, I'm very curious about a book that claims it's a "myth" and if they have data demonstrating that. Can I ask what book it is? – Athanasius Sep 18 '20 at 16:19
  • It's the "Modernist Bread". They did an impressive number of experiments. But this is not the first time that I hear that the steam is not important for oven spring. – guistoll Sep 19 '20 at 17:16
  • @guistoll: thanks. I have yet to have a look at that book. I remember having a decidedly mixed reaction to "Modernist Cuisine" when I went through large portions of it years ago. There was a lot of good science, but it was mixed in with what I'd definitely call "kitchen lore" at times. I believe you when you say they did experiments here, so I'll have to have a look. I'm certainly willing to be proved wrong if there's good science. – Athanasius Sep 21 '20 at 1:05

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