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Crustiness, or lack thereof......

Troodledoodle's picture
Troodledoodle

Crustiness, or lack thereof......

I have been baking sourdough bread for a while, and I'm happy with the crumb of my loaves, but slightly mystified at the variability of the crust. I'm hoping someone can pinpoint what makes a crispy crust, or a soft one, so that I can choose which way to go, depending on the kind of loaf I want.

The basic loaf I've been making is the one from Tartine: 75% hydration, 90% white bread flour, 10% whole wheat bread flour, 20% levain, 20% salt. I do the stretch & fold method, 3-4 hours bulk fermentation, bench rest, proof overnight in the fridge. I preheat a Dutch oven on the highest temp my oven will go to (440) for 30 minutes, then bake covered for 30 minutes, uncovered for 25 minutes. This seems to result in a very crisp crust, not too thick, the bottom crust stays crisp, but the top crust softens a little over time (but not too much).

Yesterday I tweaked the recipe (but not the method), and got an incredibly soft crust, almost like a soft English muffin! The changes I made were, I thought, minor: 75% hydration, 85% white bread flour, 10% whole wheat bread flour, 5% rye flour, 25% levain, 21% salt. Not a huge difference in recipe! But a big difference in crust. The crumb itself was much softer & moister, could the tiny amount of rye explain all of this?

As I say, I like the crispy crust, I like the softer crust; what I don't like is not knowing how to create either of those, so I'm hoping someone can enlighten me! I'm also wondering if I should try misting the loaves with water before putting them in the dutch oven - I don't get the clouds of steam come out when I remove the lid that the book says you will. 

GrowingStella's picture
GrowingStella

I can share my experience with you.

I have been misting water a few times as an experiment. I usually retard my loaves overnight, take out of the fridge right before baking them. Ocasianlly, I would choose to mist some water over loaves. I think that's what gave some nice blistering on the crust that I love. However, it did not make the crust more moist. Also, I keep loaves covered, while baking, less time - just the first 20 minutes. I can tell you, I never got soft crust, it always comes out consistantly crispy. I always bake with a mixture of flours: bread flour, spelt flour, rye flour, whole wheat flour, and usually at least 80% hydration...and like I mentioned, the crust is always crispy, and crackes if I press on it. I absolutely love the top crust, that comes out, but I would like to see the bottom crust of the bread to be a bit thinner. 

 

Happy baking!

Ford's picture
Ford

Surely, the amount of salt is 2% not 20%!

Ford

Troodledoodle's picture
Troodledoodle

Sorry, yes, 20g, 2%!!!!!!!

pmitc34947's picture
pmitc34947

Crispy, thick crusts result from a bread that was in contact with steam the longest. I have two different sized 'dutch ovens' I use in my baking. One is an oval Le Creuset Dutch Oven. The other is a Calphalon, 8 quart stockpot. The stockpot is by far the larger pot. I get thicker crusts with it which seems to prove out the concept because more moist air is trapped in the pot when the lid goes on, the thicker the crust. 

 

Mini Oven's picture
Mini Oven

meaning it takes up moisture and gives it up slower than other flours and even 5% will speed up overall fermentation. So that means if the two bakes were on the same time schedule, the one with the rye was more fermented when it went into the oven.  

Compare with other breads containing a small amount of rye.  Pierre Nury is one I can think of off hand...

http://www.thefreshloaf.com/node/5500/pierre-nury’s-rustic-light-rye-leader

Doc.Dough's picture
Doc.Dough

IMHO based on observation and physics that once the surface of the dough reaches the dew point of the oven environment, there is not much marginal value from the continued presence of steam in the oven. At that point, water vapor ceases to condense of the surface of the dough and thus stops delivering energy to the loaf much faster than hot air.  While it is true that a mixture of steam and air has a higher specific heat than dry air at the same temperature ( ranging from 1X to about 2X depending on the humidity) the heat delivered to the surface of the dough by condensing steam is 50 to 1000X that of the same mass of air (depending on the temperature change of the air as it passes over the dough). So longer baking time will thicken and dry out the crust to a greater depth, but steam is not a major player in delivering this effect. The slightly higher hydration of the dough (with the rye) will require that more moisture be evaporated to dry out the crust to a particular depth so you will probably need to expose the surface to the full heat of the oven  for a longer period of time to get it as crisp as you like it (i.e., take off the lid of the pot sooner and leave it in the oven longer).

I have not discussed the contributions of radiative, conductive, or convective heat transfer because they are not much affected by steam (or no steam) though they can be major players in commercial ovens.

I am sure that Mini has a better sense than I do of how much more oven time you need to get the surface drying effect since she is definitely the maven of rye, but I would suggest that after 5 to 10 minutes with the lid on, the dough surface temperature is high enough that you are no longer getting much benefit from the steam that is trapped in the pot and as long as you have the lid on, the temperature in the pot is substantially lower than the temperature in the oven.  The amount of steam that will escape from the pot when you remove the lid depends very much on the quality of the seal of the lid to the pot. And I have never seen a cast iron pot with anything close to a gas-tight seal so as soon as the steam generation stops, there will be little residual steam to vent when you take the top off.

Troodledoodle's picture
Troodledoodle

Fantastic responses, thank you all so much!

One last question: when it comes to oven spring, which is likely to produce the best results, baking straight from the fridge, or letting the loaves come back to room temp first?

Doc.Dough's picture
Doc.Dough

I am sure there are others who have observational data on oven spring and I await their perspective, but there are two things that are going on. When you retard, the reduced temperature assures that additional CO2 dissolves in the dough (the dough stays saturated with CO2 after an early point in bulk fermentation) and is one factor that reduces the amount of volume expansion that occurs during refrigeration (which you may or may not get back as increased oven spring).  The other is that the yeast (and LAB to some extent) produce less and less CO2 as their metabolic rate declines with temperature. So if you retard long enough to achieve the same volume that you would have with room temperature proofing, there will be more CO2 in the dough to drive oven spring as it comes out of solution when it gets to the oven and the solubility is reduced by the increasing temperature (you can think of it like warming up cold champagne - it foams furiously until it gets to equilibrium).  

The dissolved CO2 will come out of solution and contribute to loaf volume during proof if you return the dough to room temperature before you bake it, but the time constant for this process is on the order of a few hours (about the same as the time it takes to chill the dough) and if you leave the dough out for that long after it has fully proofed in the retarder you will have very over-proofed dough and likely suffer an unhappy result.

So if you allow the dough to fully proof in retard, then you should bake directly from the cooler (of course the cold dough will also handle more easily and take a slash better than if you let it warm up).  If you are using retardation for timing (i.e., to hold the dough until you have an available oven or if you want to deliver fresh baked bread at a particular time of day) then you can let it come back to room temperature and continue to proof until it is ready to bake pretty much without penalty but if you are going to do this you may need to chill it sooner than you otherwise might so that you don't inadvertently over-proof if after you return it to room temperature.  But this is not simply a gas exchange process as a lot of other things are going on in the dough in parallel which you may need to accommodate.

Another factor that will play in getting oven spring is the extent to which the dough can expand before the tensile strength of the cooked surface starch/protein is high enough to stop volume expansion (of course if there is too much residual CO2, it will just blow out somewhere and make for ugly bread).  One function of a slash is to increase the surface area of the loaf and allow volume expansion to unfold the surface like a Mylar balloon (which has no capacity to stretch) even if the surface itself is quite strong.  The dough may also degas somewhat through surface cracks and thus release CO2 that would otherwise contribute to volume expansion (one result of over-proofing).

So there is a lot going on which you can either take advantage of or suffer from depending on your level of understanding and skill.

Personally I would like to see a side-by-side bake-off of two loaves treated differently (one baked from the retarder and one fully proofed at room temperature), but that is an experiment that will require careful design and precision execution.

Troodledoodle's picture
Troodledoodle

Wow, this is so helpful, I get it for the first time! Thank you SO much.