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Steam injection oven – Keller style – safe?


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#61 pastameshugana

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Posted 02 May 2013 - 03:59 PM

Terrific!!

 

Can't wait to see the comparative bread photos.

 

Mick

 

Ha! You're killing me...

 

I love this thread so far. I'm a wee-little-baker - I only do braided challa on special occasions, but I'm enjoying this conversation.


PastaMeshugana
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#62 JoNorvelleWalker

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Posted 02 May 2013 - 08:41 PM

Suas is the author of a highly regarded professional baking book,
 
Advanced Bread and Pastry
 
which assumes use of a professional deck oven with a steam system. I've found bits and pieces of the book invaluable, for instance for sorting out why "green" (freshly ground, not aged) flour misbehaves and what to do to compensate.

 

I've read Advanced Bread and Pastry,  I was not thrilled with it.  For one thing most of the text is on pastry, not bread.  (Not that there is anything inherently wrong with pastry.)  On the subject of bread Suas credits Calvel, but it seems like chunks of The Taste of Bread were paraphrased without quotation.



#63 Syzygies

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Posted 05 May 2013 - 09:34 AM

I've read Advanced Bread and Pastry,  I was not thrilled with it.

 
Thanks. I like Hamelman so far, for that level of technical detail missing in books aimed at the home cook. I'll save my money for Calvel.
 

loaf.jpg

crumb.jpg

 

Returning to California, I bought some chain to go in the skillet in my yard oven:
 
Everbilt #2/0 x 30 ft. Straight Link Chain in Stainless Steel
Lodge Logic L14SK3 Pre-Seasoned Cast-Iron Skillet, 15-inch
Komodo Kamado Refractory Grill/Smoker/Oven

 

The skillet is 11.2 lbs and each roll of chain is 8.6 lbs; several would fit. With one roll, I estimate one can produce 320g of steam from hot water, and 260g of steam from ice. I went with more ice than that, easier to set up the steam before adding the bread, and it all disappeared in the first few minutes.

 

To revisit the Safe? angle opening this thread, I am afraid of the toxins that could be produced from the coatings (zinc or galvanized) on any kind of chain other than stainless steel. If anyone knows for sure (isn't speculating) it would be good to know a less expensive substitute. I fear that Bouchon Bakery simply overlooked this issue, not imagining that it could be a problem. Worrying about different metals is a standard topic in the barbecue community.

 

In any case I'm struggling to work with "green" flour, that we grind fresh for the flavor and nutrition. ("Green" flour, not properly aged, is notorious for having uncooperative glutens, leading to flying saucers.) The bread shown is 40% red winter wheat, 10% rye (both freshly ground, 82% or so extraction), 50% white flour. It is 70% hydration, 15% leaven, 2% salt, 1/4 tsp yeast, 40ppm ascorbic acid. Three hours bulk, three hours proof. This loaf was lighter with better oven spring and a thinner crust than I've been getting in an indoor oven. While I love the drama of more rugged loaves, so far good oven spring looks like a water balloon for me. Both adults and kids devour the loaves, at the end of the day it's food.

 

So some books state that steam is to moisten the crust. People who understand the need for techniques frequently get the reason wrong. Here, one could imagine other ways to moisten the crust, if this was all that's going on. I closed down my yard oven during the steam phase, and it came rushing out the bottom vent, with the potential for much more severe burns than hot air alone would produce. Potential, I reacted fast, but this reminded me how the steam felt on my face last week. The Komodo had clearly filled with steam. This didn't put the fire out.

 

Steam transfers heat much more effectively than hot air. This is why steaming is a fundamentally different technique than baking. It would appear that the primary purpose of steam in a commercial bread oven is to transfer enough heat for good oven spring before the crust sets. Wetting the crust is secondary; if that were all, one would simply wet the crust some other way.

 

 


Per la strada incontro un passero che disse "Fratello cane, perche sei cosi triste?"
Ripose il cane: "Ho fame e non ho nulla da mangiare."

#64 JoNorvelleWalker

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Posted 05 May 2013 - 06:53 PM

It's been many years since I've had thermodynamics, but here is my take on what goes on with steam: 

 

The thermal conductivity of steam is about the same as that of air.

http://en.wikipedia...._conductivities

 

Why steam scalds people and cooks food is primarily due to the enthalpy of condensation of water, the heat released when there is a phase change from steam to liquid water.  Bread dough is rather moist, and the surface of the bread can't increase above the boiling point of the solution, as long as the dough surface stays moist.

 

My guess is that initial steam heats the dough surface faster than a dry oven, but then helps keep the surface temperature of the dough from rising further, as it would in a dry oven.  Crust formation is delayed.  Thus with steam the dough has a longer period of time during which it is both hot and plastic, increasing oven spring.

 

This is entirely theory on my part, and is not stated as truth.



#65 Syzygies

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Posted 06 May 2013 - 03:13 PM

bake.jpg
loaf.jpg

I bake in my BGE, and I find that the airflow through the top vent effectively negates any impact of the steam.  In plain English, any steam generated quickly goes up the top vent & doesn't hang around long enough to keep the crust flexible in the initial baking stages (to allow for max oven spring).

 

Why steam scalds people and cooks food is primarily due to the enthalpy of condensation of water, the heat released when there is a phase change from steam to liquid water.  Bread dough is rather moist, and the surface of the bread can't increase above the boiling point of the solution, as long as the dough surface stays moist.

 

I'm continuing to have better luck with steam in my yard oven than I ever did indoors. After adding ice and putting in the loaf to bake, I totally shut down the air intake vent and the top vent for a few minutes. The fire resumes just fine when I open the airflow back up. I believe that my relative success is because the Komodo Kamado is much tighter than my indoor oven, and bakes to a greater extent using radiant heat. I've moved to the main rack in an effort to actually reduce the radiant heat effect, and I'm baking at an air temperature of 400 F, getting results similar to an indoor oven at 460 F.

So I agree with the above guess at the physics. It takes a great amount of energy to turn water to steam, and the steam releases a great deal of energy as it turns back to water.

The other calculation I've wondered about: Water expands by about 1600x as it turns to steam. I estimate that my indoor ovens are each around 140 liters. This is also a reasonable guess for the volume of my Komodo Kamado. Bouchon Bakery's recommendation to use 350 grams of water will yield 560 liters of steam, or enough to fill either oven four times. So of course we feel steam exiting these ovens. There is steam left to do the job. On the oother hand, less than 90 grams of water won't fill the oven once with steam, at which point one would expect to see less of a benefit from the steam.


Per la strada incontro un passero che disse "Fratello cane, perche sei cosi triste?"
Ripose il cane: "Ho fame e non ho nulla da mangiare."