#41  
Old 01-06-2011, 11:37 AM
Il Pizzaiolo
 
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Location: San Antonio
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Default Re: Tall fire, yes. Wide fire too.

Hi Karl!

Glad to hear someone actually followed up on my comments. As you now know, once you make a big batch it is hard to go back! The results are too superior!

There are many things different about a WFO from indoors. And there can be little doubt that higher heat conduction from the hearth is one of them. I am convinced the temperature profile in the oven vs. time is rather different and another contributor. The big batches use the oven the way it was developed to be used. No spraying or jacking around with it. Just bread and heat! And MAGIC!

Thanks!
Jay
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  #42  
Old 01-06-2011, 11:52 AM
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Join Date: Apr 2010
Location: Northern Virginia
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Default Re: Tall fire, yes. Wide fire too.

I was amazed at the steam a 16 lb load generated last weekend. My door must be not as tight as it could be; steam poured out the chimney. It was a cold day, so it was pretty visible but, at first, I thought the bread was burning. It was just steam. Lots of it.

I guess temperature profile could be a factor since there must be a pretty big drop when you first load, followed by a ramping back up. Unlike a kitchen oven, in which the heat is all on or all off (or, I guess, with gas, almost all off) the heat is always there and just has to seep back up to the hearth floor. I would guess there is a fairly good swing zone in a kitchen oven thermostat between heat on and heat off, with a profile cycling repeatedly from below the set point to above the set point. The profile in a WFO for each bake would be just one cycle from start temp, down some, then back up to nearly start temp.

Lots to learn. Thanks for your help.
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  #43  
Old 01-06-2011, 01:07 PM
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Default Re: Tall fire, yes. Wide fire too.

Quote:
Originally Posted by kmrice View Post
steam poured out the chimney. It was a cold day, so it was pretty visible but, at first, I thought the bread was burning. It was just steam. Lots of it.
So that's what that was. I had that too and thought the same thing.
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  #44  
Old 01-06-2011, 01:53 PM
Il Pizzaiolo
 
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Default Re: Tall fire, yes. Wide fire too.

The release of water vapor (and other stuff like alcohols) during baking is nontrivial. You can expect to lose between 10% and 25% of the bread weight during baking. For a 15 pounds of dough that would be in the 2 to 3 pound range or about 40 to 70 cubic feet of pure water vapor at standard temp and pressure. At oven temp the volume will be about twice that. The volume of your oven is around 20 cubic feet so the water vapor will effectively purge the oven of much of the other gases and you will get about 2 pounds of water condensing into steam outside the oven as it escapes.

Interesting!!! I hadn't pondered that before.
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  #45  
Old 01-06-2011, 05:44 PM
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Default Re: Tall fire, yes. Wide fire too.

Yes, very interesting!

According to McGee in On Food and Cooking, oven spring enhanced by steam effectively ends after 6-8 minutes when the gluten proteins firm up enough to resist the expansion of alcohol and gas within the loaf. He also states that commercial bakers inject steam into their ovens at low pressure. Given the grand volumes and pressures cited by texassourdough, could this mean that a fully-loaded brick oven might actually benefit from a leaky door?

John
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  #46  
Old 01-06-2011, 07:56 PM
Il Pizzaiolo
 
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Default Re: Tall fire, yes. Wide fire too.

Hi John!

I think most of our ovens are a lot leakier for gases than we probably think. I am confident the bulk of the water evaporates (or transpires) to the oven interior during the oven spring period (which is when you want the bread skin to be soft and malleable so the bread can expand). The heating of the dough does three things to make the dough "spring". First it heats the gases in the bubbles in the crumb which cause the gas (mainly CO2 but some water vapor as well) to expand. Second, and supposedly more importantly, CO2 solubility in water and thereby dough decreases as temps rise so CO2 comes out of solution in the dough and forms more bubbles and/moves to the existing bubbles in the crumb. The third effect, which is much less significant, is the vaporization of alcohols which augments the CO2 effects and provides a lot of the aroma you recognize as baking bread. The largest changes in these factors occurs in the first 10 minutes or so and is mainly CO2 driven.

I am a fan of McGee and I have read a lot of his book. While I would agree that most of the effect TYPICALLY occurs in the first 10 minutes (and maybe 6 to 8), the degree of oven spring is clearly a funciton of oven humidity as well. At 6 minutes the heat has not penetrated to the core of the dough so there is still potential for more oven spring if the skin of the loaf remains flexible (i.e. adequate humidity!). Experimentation with cloches suggests to me that oven spring can continue for at least 15 minutes and possibly 20 or more. (Tartine suggests a 20 minute "covered" approach with a dutch oven. I know I see some difference between 10 and 15 minutes closed and believe I see a diff between 15 and 20 - particularly in "tight" containers that don't lose much steam.

Most ovens probably have about the right "steam loss" rate to make them work well.

Bake On!
Jay
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  #47  
Old 01-06-2011, 11:38 PM
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Default Re: Tall fire, yes. Wide fire too.

Any secrets on ramping up from a 2 lb to a 16 lb load?
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  #48  
Old 01-07-2011, 04:16 AM
Il Pizzaiolo
 
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Default Re: Tall fire, yes. Wide fire too.

Yeah, forget the mixer. It is easier to mix it in a big tub. Just do the whole thing by hand. Chad Robertson's book Tartine covers the process better than anyone else but it is kind of overkill to buy the book for just the process. The gist is to make your levain the night before, then mix the final flour the next morning. It is best to leave the salt out. Mix it until all the flour is wet, then let it sit about a half hour. Add the salt with a bit of reserved water (100 to 200 grams water for 15 pounds final dough) and squeeze the dough to get the salt mixed into the dough. You will feel it tighten significantly when the salt is added. Then give it a half hour and give it say 8-16 big stretch and folds (S&Fs), then every half hour for about two hours being increasingly gentle and decreasing the number as the dough develops and grows more fragile. After about 2 1/2 to 4 hours depending on temp, levain activity, etc. you should be ready to form loaves. Then you are back to normal process. I do spray the oven lightly with water but...not only lightly - just before I put in the first loaves and as I finish. Work fast loading. And don't open the oven until you think the bread is done though you may need to be early until you learn your oven.

This approach should, with a little experience and practice, give you perfectly developed dough.

Good Luck!
Jay

Last edited by texassourdough; 01-07-2011 at 04:40 AM. Reason: Add some details
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  #49  
Old 05-05-2011, 07:07 AM
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Join Date: Apr 2011
Location: Tasmania
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Default Re: Tall fire, yes. Wide fire too.

that looks like GREAT bread!
ive just built a 1.2m tuscan domein the tasmanian highlands.It seems to hold heat extremely well,but I havent attempted bread yet.Cant wait!
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  #50  
Old 05-05-2011, 10:41 AM
Il Pizzaiolo
 
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Default Re: Tall fire, yes. Wide fire too.

The big load that I did 2 weeks ago was done by hand in a 20 qt stock pot. I did learn that I the feel that I have been getting from 1.8Kg batches translates to the big batches. Yes it's more work because of the additional bulk, but overall, it's about "mise en place" and mostly about how to move and proof the dough so that you can load the oven quickly. I haven't gotten around to getting a proofing board but will..

Chris
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