The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Wet Steam

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ehanner's picture
ehanner

Wet Steam

I'm doing some computer work for a local engineering firm that specializes in heating ad AC systems. They design and sell a lot of steam boilers and are very familiar with the industry and the sub specialty of bakery's. I noticed a client name that I recognized as a old name in the community that is a well known bakery and asked what they were doing. I was surprised to find they were working on the steam system for a large commercial tunnel oven.

According to my friend, the steaming method used in these ovens is a closely guarded secret or at least not well known. The oven they are installing is an Italian model and they don't provide any information what so ever regarding steam. Nothing about sizing of nozzles or flow rates or length of the steam blast is part of the information from the manufacturer. Apparently this is a common  situation they run into often.

The interesting thing I learned that will be of interest to Fresh Loafers is that they purposefully make a wet steam. I have noticed when using my hand held steam generator that the first few seconds of the output,  when the pressure is highest, the steam is quite dry. Gradually as the pressure goes down it begins to spray a mist of wet steam and it seems like it is spritzing a little water along with the steam. I read somewhere that the benefit of using a steam generator was that it does produce a dry steam which is beneficial to the process. Now I'm questioning that belief.

If the point of steaming is to moisten the surface of the dough to aid in gelatinization of the surface so the spring will be more effective and give the surface a nice shiny surface, well then a moist steaming would be better I would think. My friend says he has installed many of these and that's the way they all are, at the insistence of the baker.

So, what does this mean to us? The procedure that Hamelman suggests is adding water to the pan in a quantity that is more than what will be boiled away in 10 or so minutes, then removing the pan to stop the steam effect. This sounds to me like it would produce a wetter atmosphere than a smaller amount that would be gone in a few minutes or my usual 10 seconds of high pressure dry steam. I'm thinking that releasing the dry steam from the steam generator and using the wet secondary steam would produce a better result. I have been doing the opposite. 

I hope I'm not the only one that finds this interesting. The subtleties of the first few minutes  in the oven can have quite a dramatic effect on the bread.

Eric 

nbicomputers's picture
nbicomputers

in a word yes

bakers use low pressure boilers that run below 15 psi  anyrhing above 15 psi and the steam will be dry and cracl the crust or blister the bread.

dmsnyder's picture
dmsnyder

Hi, Eric.

Well, I find it very interesting! I think steam/humidity has multiple effects on the loaf. Some may "prefer" dry steam and others wet steam.

One effect is to keep the crust from forming until there has been good oven spring. I think this means preventing drying which means keeping the hot air moist.

Another very different effect is starch gelatinization, which makes the crust shiney. This actually requires the crust be wet with very hot moisture. I think this occurs after the crust is pretty well formed. I find that if I keep the loaf covered longer, I can actually make the crust shinier than I like.

Hamelman, somewhat cryptically, differentiates "humidifying" from "steaming." I am at the office and somehow left my copy of "Bread" at home. But, somewhere, he describes the method that I have been using for the past few months. He recommends pre-heating two recepticles. (I use a metal loaf pan and a cast iron skillet.) Before loading the loaves, you throw some ice cubes in the first to "humidify" the oven. When you load the oven, you pour hot water into the second to "steam" the oven.

I remove the water, if any is left, after 5 minutes when baking rye breads (based on Greenstein)and about mid-way through the bake for mostly-wheat sourdoughs.

So, what happens when you bake under a cover (roaster, SS bowl, la Cloche, whatever)? I would speculate that you initially get dry steam as moisture starts to evaporate from the loaf. As the air gets saturated or the vapor condenses on the surface of the cover, you are more likely to get water in liquid phase on the surface of the loaf, as you would with "wet steam."

Watching the action baking under a Pyrex bowl would probably test this.

What are your thoughts about this?


David

ehanner's picture
ehanner

My feeling is that when you open the door and add hot water for steam, the oven goes way down. Adding a substance that boils at 220F and resists attempts to get hotter into a 450F oven has to lower the temperature considerably. Covering a dough ball with a bowl protects it in a similar manner I suspect delaying the blistering heat that kills the bacterial activity and stops the spring. IMHO, the fact that Susan's Magic Bowl works at all is testament to the insulating properties of the bowl. Being able to add steam to the bowl is a big advantage. Sometimes I will spray the paper around the dough with water just before I cover it.

Eric 

nbicomputers's picture
nbicomputers

actualy steam can get hotter than 212 F just as ice can get colder than 32F the is called the http://en.wikipedia.org/wiki/Heat_of_fusion

the propblem is that only after that change of state is complede can the temp go above or below that number

so when ice is all ice with no liqued in can get colder and when steam is all steam it can get hotter

while the liqued part cannot get hotter than 212 the uper part of your oven where there is only steam the steam can go way above 212 or what is called supper heated if the steam is under pressure in can get very hot

check out you tube for some examples of liqueds that while under pressure have been supercooled.

ps just put a jewish honey cake in the oven 100 percent white rye...and you thought rye was only for bread...

sphealey's picture
sphealey

=== actualy steam can get hotter than 212 F just as ice can get colder than 32F  ===

It can, but only in a pressure vessel.  At 1 atmosphere pressure boiling water/steam will top out at 100 deg.C / 212 deg.F.  In the home, and particularly after we put the water in the oven, we are dealing with 1 atm and the temperature will be below 100 deg.F.

See this link for an understandable explanation.

Ice of course can get as cold as the surrounding envirnment at any pressure.

sPh

coffeemachine's picture
coffeemachine

<cite>It can, but only in a pressure vessel.  At 1 atmosphere pressure boiling water/steam will top out at 100 deg.C / 212 deg.F.</cite>

 

This is not true. at 1atm water boils (or steam condenses) at 100deg C. This is the temperature at which water and steam can coexist, just like water and ice can only coexist at 0 deg C at 1atm. this is actually how 0 and 100 degrees C originally got defined (a little history of science here). steam can be any temperature above 100 deg C ( we're still talking about 1atm here). The reason people associate steam with pressure is that if you have a fixed volume (i.e. your pressure cooker), and you keep heating up the steam, the pressure will rise.

 

I think what happens with using steam in baking bread is that steam condenses onto the surface of the cold dough (dough takes time to heat up, so it's probably below 100C for the first few minutes in the oven), and that moisture keeps crust from forming. I don't know for sure if this is right, but the previous paragraph is.

 

violet 

sphealey's picture
sphealey

=== I have noticed when using my hand held steam generator that the first few seconds of the output,  when the pressure is highest, the steam is quite dry. Gradually as the pressure goes down it begins to spray a mist of wet steam and it seems like it is spritzing a little water along with the steam. I read somewhere that the benefit of using a steam generator was that it does produce a dry steam which is beneficial to the process. Now I'm questioning that belief. ===

You aren't going to see any dry steam in a home or light commerical environment except as noted at the very exit from a pressure vessel.  And I would question how "dry" that really is; I suspect it is just "less wet" in terms of the saturation diagram.  Which is a good thing because steam hot enough to be truly dry can maim/and or kill quite easily.  In the power plant where we had a bit of the "danger is my middle name" attitude we treated steam with great respect.

In the home environment we are dealing with hot water vapor, which again as noted is probably what we really want anyway in terms of absorbtion by the surface of the dough.

sPh

Pablo's picture
Pablo

This is very interesting.  Eric - do you use a cover in your oven that you are able to inject steam into or are you injecting steam into the general oven cavity?

Recently my starter got away from me and I was encouraged to check out Carl's starter.  I found this intriguing quote on one of the pages there:

"Steam was injected into the oven for about 12 minutes of the baking, and was accomplished via the common amateur configuration of stovetop pressure cooker connected to copper tubing running into the oven."

Currently I use a pan of rocks with which I presteam and steam by throwing boiling water onto the rocks.  I like the idea of the rocks acting as a heat sink to minimize the oven temperature drop from opening the door.  I am beginning to see that there are many more options than I have considered.

:-Paul

Mini Oven's picture
Mini Oven

Eric, one little step Susan does with her bowl is rinse it with warm water before covering the dough.  I've tried it both ways, dry and rinsed, and can say there is a difference, even more so if the inside of the bowl is misted with water.  Then it becomes a moist chamber right away. 

Another interesting "happening" is that the bowl insulates the top and sides from the blast of heat while the bottom of the loaf gets heated directly & quickly.  Moisture in the air can act like insulation also, and I can't help but think this plays a big role in an open oven where a magic bowl can't be used.  I've noticed that when the steam is present for too long the crust gets tough and thick.  

The bowl effect works exceptionally good when convection is involved.  The convection tends to dry out the dough surface when blowing.  The bowl shields the dough.  Important is also being able to remove the moisture after oven spring so the loaf can get on with browning.  (Now if the desire is for a giant Dum Sum or steamed bun, then forget releasing the wet steam.)

Mini O

ehanner's picture
ehanner

Paul,
I've tried just about everything to make steam, even the pressure cooker and tubing. By the way I don't recommend that one, to much can go wrong. The deal with covering the dough eliminates the need to steam the general oven cavity. I have a steam table catering pan that fits on my stone that has a 1/4" hole drilled in the side near the top. I apply steam from a hand generator under pressure through the hole for about 10-15 seconds. 10 minutes later I remove the cover and bake another 15 or so minutes. The results are the best I can produce.

Then I discovered Susan's covered bowl method which doesn't involve any steam. Just (as Mini-O points out) a little water sprayed on the inside of the bowl that turns to steam when the bowl heats up. For a simple solution you can't really beat the bowl or turkey pan or what ever else you use to cover the dough.

The fall back method most of us use is the most common. The pan in the bottom and ice cubes or hot water depending on what your approach is. The entire oven is steamed rather generously to some degree depending on method, pre heating and a number of other variables.This method is the easiest to accomplish and the biggest chance to break the glass window in your door (which I did for the first time last week).

I started this thread because I found it interesting that a wet steam was prefered in a fancy Italian oven and according to Norm it sounds like that's a widely known concept.

Eric 

Pablo's picture
Pablo

The moist bowl might be the way to go, but I just can't .  I love all the drama of the steam roiling up from the heated rocks.  I could live with the roasting pan and hand steamer through a predrilled hole, that's pleasing to my inner tinkerer.  A simple inverted bowl is just too easy!  :-Paul

ehanner's picture
ehanner

Paul,
I can see you haven't had to replace the electronics controls or glass door in you oven yet. You need a little convincing along with your erector set!

Eric 

Pablo's picture
Pablo

Experience does have a nasty way of raining on my parades.  It's true.

:-Paul

Soundman's picture
Soundman

Hi Eric,

All interesting, but I'm still a bit confused. If steam can be hotter than 212 dF, does that have an impact on home-baking, do you think?

I have a steam cleaner also, and I find that if I don't let it heat up enough, it will produce a spitting spray that seems more like very hot water than steam. When the thing is hot, I can see the steam in the air as it condenses. However, when I use it to steam the oven, I can't see anything coming from the output port. Is this because it doesn't get a chance to recondense into water vapor? Will it be delivering a good and useful blast of steam, though I see no evidence of same?

Also, once the steamer is hot, it produces the identical visual result in the air from start to finish. Do you still think this is a 'drier' steam? Do you still think drier steam is less effective?

Sorry I didn't see the thread earlier.

Soundman (David)