January 15, 2008 - 4:38pm
Steaming
I have 3 bread books: RLB's 'Bread Bible', Leader's 'Local Breads' and PR's 'Whole Grain' book. In Bread Bible and Local Breads the authors recommend obtaining steam by using ice whereas PR says that's old school and that hot water should be used instead. Is there a difference in the outcome of ice versus hot water and if so, what's the difference in effect?
Fiona
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You can use ice but the results are not going to be the same unless some adjustments are made. Basically, the problem is that converting a considerable amount of ice into steam requires enormous amount of energy. Say, if you use 1 cup of ice it would take ~675 kJ of energy to evaporate it, if your oven has 3 kW element it would take it's entire heat output over almost 4 minutes to do so, even if we assume that there's no losses (and there are). So, when ice is used oven temperature drops dramatically, steam is not generated fast enough and in large enough amounts. Of course you can adjust by overheating the oven before loading your bread, using less ice - which I think most people do and so on, but I think using hot water is much simpler. For what it's worth both Hamelman and Amy Scherber say "use boiling water", and in his famous article Bittman calls using ice "not good for the oven, and not far from ineffective".
I've gone back and forth on this.
I think it partially depends on what you are dumping the ice/fluid into. I was happier with hot water when I was pour it into a thin metal brownie tin. Then I found a cast iron tray at Goodwill that really got hot. I found that hot water would completey evaporate in about 10 seconds, sometimes even before I got the oven door closed, whereas the ice would evaporate over 2-3 minutes and produce steam longer. So with the iron tray I find the crust improves the most when I use ice.
Either ice or water directly on the oven floor is pretty rough on the oven. I'd only suggest doing that if you are itching for a kitchen remodel.
I have been dumping the ice into a thin metal container. I've read recommendations to use a cast iron skillet and the only thing that's been putting me off purchasing one is that the metal containers I have been using don't take long to go rusty. I don't mind replacing those every now and again because they are cheap but a skillet is a bit more of an investment if it's going to do the same thing and go rusty (I thought I could rectify this by putting oil on the tin after use but the next time I put it in the oven it smoked the place out).
Small cast iron skillet should cost under $10. It will go rusty almost immediately, but who cares? I mean if you don't already have it chances are you don't need it for anything else.
FWIW, I've read that solid fat (shortening or lard) is much better for seasoning cast iron than oil. The explanation made perfect sense when I read it, but I don't remember enough to try and repeat it here. My husband, who proudly uses antique cast iron (and one new piece) says he gets better results with the solid shortening than with oil.
The main reason I know is that oils tend to get tacky. Solid fats don't seem to do that. I use either lard or palm oil shortening on my cast iron and wok.
Russ
I have also gone back and forth on this. I understand the thermodynamic argument above, but the problem is this: unless our oven has a steam generator (and I only know of one very expensive one that does) or we somehow rig up an external steam generator (which is difficult), what we are going to get is water vapor not steam. The goal is to get that vapor up around the loaf in the first few minutes of baking. And I often wonder if the ice cubes sizzling away on the cast iron don't produce more usable water vapor in the first few minutes than the 180 deg.F water bubbling calmly away as it slooooooowly approaches boiling.
That said I am currently using water from the teakettle into a cast iron pan preheated to at least 500 deg.F. Would love to have that steam generator oven though...
sPh
I've been using boiling water in my broiler pan. My theory is to get as large of a surface area as possible. Don't know if it matters but I get a lot of steam coming out my oven vent. One thing I wonder about though is if the steam from the ice is being created via melting and then boiling or just sublimation. That might make a difference but that is also beyond my thermodynamics knowledge..... Does anybody know if ice sublimates in a 500 degree oven?
It's ice to water to steam, there's no question about that.
One thing I have read is that for steam to do anything useful, you have to get some pressure behind it. This is tough in a home oven (which is vented), but I don't see how you could get any pressure using the simmering water produced by ice cubes. I sacrificed a cast iron skillet to the rust god who lives in my oven, and I think it works quite well. I pour about 2 cups of water into it through a crack in the door--I put a funnel onto a section of copper pipe so the door is very nearly shut.
If you're opening and closing the oven, you're obviously wasting a lot of heat. Consider adding some extra thermal mass, such as an additional baking stone or a couple of bricks. I don't recommend rocks, as some crack (occasionally violently) if heated to high temps.
I have been using hot water for steaming as well.
I use an electric oven with heating element on the bottom, so I use a cast iron pan on my lowest shelf preheating with my baking stone on the shelf above.
On the top of my stove towards the back is my vent. I take a dish towel and roll it up into a log shape and shove it up under this vent on the stovetop. I then place a cutting board up against the towel to hold it in place. Once I place my bread on the baking stone I pour approx. 190 degree water into the steam pan. And close it up. I mist the bread another couple times every 30 seconds with a plant mister. Then let it bake, after 10-15 minutes I pull the towel from the vent hole, and let remaining steam escape the oven. When it is time to rotate my bread, about half way through baking, I pull the steam pan with remaining water from the oven and let cool on the stove top.
Just what works for me,
TT
I finally bought a cast iron dish at the weekend. I had always seen those flash French cast iron dishes that cost upwards of $150.00 here and thought that was a waste just to put water in. Anyway, the recently purchsed one didn't break the bank at $7.50. I cannot beleive what a difference it made. I have the world's most useless piece of crap oven. It'd be better as a heater than a cooker and the thermomoter dial can be out by up to 50 degrees so that an internal thermomoter is not so much a luxury as a necessity. Normally when I place the loaf in the oven and use ice, the temperature drops in half in next to no time. I baked about 8 loaves over the weekend, all using ice and the new little cast iron thing and there was hardly any real temperature drop. I'm so impressed and now I can toss out all those thin tins I have been using.
Fiona
I have a gas oven and the heat comes from the bottom. My stone sits on the bottom rack. If I'm to use a cast iron skillet for steaming, I'm a little perplexed as to where to put it. If I put it on the floor of the oven, the top of the pan will be about a centimeter from the bottom of the stone and the pan is about 6" wide while the stone is about 14" wide. This doesn't seem to allow much room for steam to travel to the dough. Should I move the stone up to the middle of the oven or put the pan in on the top shelf? Neither of those solutions seem like very good ideas to me since my oven isn't a very good one and it probably gets dramatically cooler the farther up you go. I got distressed after trying all these things and began just throwing ice onto the floor of the oven, but after reading this thread, I'm second guessing that method. I would like to go back to cast iron and would appreciate any input on the matter. I know I should probably just go with what's given me the best results, but my results are generally a little erratic so it's difficult to say. Thanks!
I'd be inclined to move your baking stone up to the middle of the oven. I too have a fiarly useless oven with incredibly variable heating throughout. I find the baking stone negates some of that variability. For me, the key is to heat the oven up for ages to get it really warm (I always put if on at the highest setting for at least an hour but usually longer). I think having the stone and the steamer at the same level might result in the steam generally going everywhere but into your dough. It's all about trial and error in my opinion and on that basis alone, I'd see how you go for a while moving the stone.
Fiona
It seems to me there is a market for a specially-made steaming device for home ovens. Isn't there a bread baking engineer out there that would just love to invent such a device?
Assuming commercial bread ovens are designed to deliver optimal steam, how do they do it? Continously for a set time? In bursts, e.g., for 5 seconds every 30 seconds for 5 minutes? What level of humidity is optimal?
How about having more than one pre-heated receptacle in the oven and pouring hot water into each in succession, say every minute for 3 minutes?
How about a device something like a stovetop espresso maker that is heated on the stove and then placed in the oven where it generates steam?
Hmmm ... A brass boiler holding 250-500 cc of water with a nozzle at one end and a pressure release valve (for safety). Heat the whole device in the oven. When ready to bake, open the nozzle to inject steam into the oven for as long as the water lasts. All parts would have to be heat-tolerant.
I'm not good at this kind of designing. There must be folks among us with more talent to apply to this problem.
David
I have come to understand that if you cover the bread with a bowl or pan of some sort even a clay bell La Cloche, you can forget about steaming. Preheat the cover if it's clay if you wish and remove it after about 15 minutes. Sometimes I will spritz water around the dough on the paper to add additional moisture but it's not absolutely necessary.
Eric
there are two ways bakers ovens delever steam
The old way was an external low pressure boiler was set up by a pipe that ran into the oven with a lot of small holes driled it to it. a valve on the boiler was manualy opened and the stean was injected into the oven. The reason for low pressure (below 15 PSI) is because above 15 psi the steam would become dry steam and cause the bread to crack. the steam was injected about 5 minutes before loading the oven and was continued during the total time the bread was loaded. about 10 minutes after the bread was loaded the valve was turned off the the damper was opened on the oven so the steam could escape and the baking completed
new ovens are set up with steam injectors and a computerized control system.
you would press a steam button and about 15-20 seconds of a preheated water would be injected into the oven by microfine injectors the water droplets are so fine that would vaporize instantly. then the oven would be loaded (and you have to be very fast and close the door rightaway after each peel load. after the over is full you would press the steam injecting another burst. these new type of ovens to not have a damper because the steam amount is computer controled.
I like the old way better because you have a constant supply of steam and have more time to load the oven.
i guess if your home has low pressure steam it would be easy for a plumber to run a small steam line into your oven. in side the oven all that is needed is a 1/2 inch copper tube with a cap on the end and small hones driled along the tube. I guess you would need to be able to un screw the end cap so once in a while you could drain the condenced water.
i think you might get some strange looks from the plumber when to tell the guy what you want :)