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So I baked a rye bread last night (in a bread pan). It was a new recipe for me and I had to adjust some things in it due to missing ingredients, so I could not fully rely on the time and temperature recommendations. I therefore baked it until the bread reached the recommended 97˚C/207˚F (which actually took about the same time the recipe said). However, after cooling, I thought it to be too doughy and I would have liked it to be baked for maybe 20 minutes more.

This makes me think that you can't follow temperature as an indicator of doneness. Maybe it works with breads that have a certain moisture content (my dough was probably a bit wetter than it should have been), but not regeardless of the composition of the dough.

Most temperature recommendations tend to range from 94˚C/201˚F–98˚C/208˚F.

My questions then, is:

  • Is there anything particular that happens at these temperatures?
  • Are they reliable indicators of doneness?
  • (Optional question expecting just a simple explanation: What does it mean, technically, that a bread is done/baked? Not taking into account the importance of also forming a good crust.)
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While For baking, is there a common “done” temperature across different kinds of breads? is related, it does not ask the question of why a certain temperature is recommended. –  citizen Nov 13 '13 at 7:20

1 Answer 1

up vote 13 down vote accepted

What happens to bread when it is done

Yes, there is something particular what happens at a temperature in the mid-90s. Not all details of it are proven, but the major outline is, and the hypotheses about the details are solid enough to make it into textbooks.

Starch is contained in tiny granules, a few micrometers in diameter. When heated in the presence of water, there is a specific temperature at which these granules burst. The molecules of starch come in contact with water and the water molecules get lodged in the nooks and crannies of the much larger starch molecules. This process is called gelating.

You can observe it easily on the macro level. Just cook a bechamel or starch pudding on stovetop, stirring constantly. The liquid will stay rather thin until all will thicken at once, just before you see the first bubbles of boiling. This is when the starch gelates.

The same thing happens in bread too. This is why you want to heat the bread to this temperature. If you don't, you will have raw starch inside, which doesn't taste well.

The exact temperature at which this happens varies a bit with the type of starch. It is not the same for rice and wheat, for example, and I think that it is also a bit different between different wheat cultivars. But the range within this variation occurs is not so wide, all references I have seen move somewhere between 94 and 98 degrees Celsius. So the recipe author just picks a temperature he knows to work for the flour used in the bread, maybe also accounting for some additional heat transfer after taking out of the oven.

Can you use temperature as an indicator for doneness

The theory says yes. My personal experience also says yes. Why did you feel that your bread was too doughy? There are different reasons why this could have happened. You could have measured it wrong (with the probe being too close to the surface, where the temperature is higher). You could have cut it too early. (Bread is always doughy before the first starch retrogradation, which occurs maybe 1 hour after baking). It is also possible that the bread was actually done in the sense of gelled starch, but that the recipe produced a rather moist bread and that you have grown accustomed to dry breads if you normally bake your breads for a very long time, so your brain perceived the unaccustomed texture as "not right". Or it is possible that something went wrong with the leavening, making the bread too dense. Dense bread is always doughy, you cannot bake the moisture out of it.

technical criteria for bread doneness

There are two big chemical changes which happen to bread while baking. The proteins in bread (the gluten) have to harden. Before that, they are soft and pliable. At some temperature, they become rubber-like. The hardened gluten gives the bread structure.

The second change is the starch gelation I explained earlier. When this happens, the liquid part of the dough (dough consists of a liquid phase suspenede in the elastic gluten mesh) thickens. Gelated starch gives bread a fluffy, soft body.

As the starch gelates at much hicher temperatures than proteins denature, bread is taken out of the oven when the starch is done.

The third step is the starch retrogradation. In retrogradation, starch loses the water which it took during gelation. There are three big stages of it, after each the texture changes drastically. The first happens at about an hour after getting out of the oven. This is when the bread is considered done by textbooks. In practice, there are many people (including myself) who like the taste of the moist hot bread just out of the oven, and they consider it done at the previous step. The second happens after about 24 hours; after it, the bread is considered stale. The third step takes several days, and after it, bread is considered inedible, because it becomes hard as wood.

So technically, bread is considered done after it has been baked to gelation temperature and then left alone for 1 hour.

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Dough is NOT a liquid, the molecules are not in general free to move around the liquid phase, and it doesn't really flow so much as deform (depending on the dough); it is a complex aggregated substance.. It would be more accurate to say "when the liquid phase within the dough" thickens... –  SAJ14SAJ Nov 13 '13 at 11:42
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Ah, a great answer, @rumtscho. I'm guessing then that my bread is in fact done, in the technical sense, but that I had too much water in the dough for my taste. Then I know not to bake it for a longer time next time, but to decrease the amount of water. And for my other breads which maybe I'd like to be a bit more moist, to add more water and follow temperature rather than time. Interesting! –  citizen Nov 13 '13 at 12:48
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@rumtscho: About the first stage of starch retrogradation, is it driven more by the temperature drop (when the bread is cooling, which can take ~1 hour), or by time? (I know bread becomes stale very quickly if you put in your fridge.) –  citizen Nov 13 '13 at 12:52
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@citizen good follow up question, but if I ever knew the answer, I don't remember it completely. It is not just time, but I don't know what part other factors play a role (air moisture and bread type are obvious candidates). Maybe you should post it as a separate question, and hopefully somebody will be able to answer it. –  rumtscho Nov 13 '13 at 17:11
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Part of the "doughy" feeling of this bread could have been due to the rye flour. Rye flour has a lot of gums called pentosans. These can absorb up to five times their weight in water, but can also take a long cooling period to seem "done" (releasing this water back to the other starches? I don't know.) It's pretty common to let breads with a lot of rye flour rest up to 24 hours before cutting. –  sourd'oh Nov 15 '13 at 18:08

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