story on steam

Discussion in 'Pastries & Baking' started by thebighat, Jul 29, 2002.

  1. thebighat


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    The Washington Post has a great story in the food section on baking bread with steam. I'd put in the link, but can't seem to get it to paste. Check it out before it goes away, and maybe Isa or someone knows how to get it here.
  2. kimmie


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    There, before it goes away!
    Steam Heat

    By Robert L. Wolke

    Wednesday, July 24, 2002; Page F01

    I recently completed training as a chef and have asked everyone at the school the following question, without getting a satisfactory answer. Maybe you can help. We were told in our bread class that in order to get the best browning and crisping effect on French bread, we should bake it in an oven that has steam in it, either from spritzing water into the oven or by putting a pan of hot water in the oven during baking. Why would moist heat result in a crispier product?

    It's counterintuitive, isn't it? You'd think that moisture would make the crust soggy, not crisp. Nevertheless, it does work.

    According to Prosper Montagne, in his encyclopedic Larousse Gastronomique, "Bread is a food which is used, and abused, more than any other, especially in France." (He never bought a loaf of white bread at an American gas station.)

    But despite Montagne's disloyal dig at his countrymen, many people -- even outside of France -- consider a golden brown, crisp-crusted, light-but-chewy baguette fresh from the boulangerie to be the best bread in the world. When I lived in France, I relished carrying home each morning before breakfast a long, slender baguette; or else a ficelle ("string," an extra-slender baguette) or an épée ("sword," a half-dozen oblong rolls strung together like leaves on a stalk), the last two intended to maximize the crust-to-crumb ratio. (The soft interior of a bread is called its crumb.)

    Nevertheless, when I lived in Puerto Rico I found the Puerto Rican crisp-crusted pan de agua ("water bread") to be every bit as good as the French version, though unfortunately not as famous because of a comparative lack of chauvinism. But read on; you won't have to run over to Paris or San Juan to pick up your daily bread. There is great "French bread" to be had right here at home.

    As many of us have discovered to our disappointment, it is difficult to duplicate good French bread in our own kitchens. The major reason is that the professional bread ovens have built-in steam injectors, and it's the steam that does the crust-crisping trick. Many recipes for home-baked French-style bread substitute either placing a shallow pan of hot water on the oven floor or spritzing a mist of water into the oven from a spray bottle. I've even seen recipes that advise tossing a few ice cubes into the oven. But a sauna is not the same as a steam bath.

    Steam not only makes the crust crisp but helps to produce a well-risen, well-shaped loaf. The science behind these phenomena is quite interesting. Here's the scoop.

    What Steam Does

    If a long lump of dough were to be put into a hot, dry oven instead of a steamy one, its large surface area would quickly dry out, producing a tough, inflexible skin that resists expansion. The dough then wouldn't be able to rise to its maximum volume or optimum shape, and the loaf would turn out to be puny and misshapen. At the same time, the interior crumb would be unable to expand to its sought-after open structure and would turn out to be denser than desired. If steam is present during this early phase, however, it will soften the surface and allow the loaf to expand its best structure in what bakers call oven-spring.

    In the later stages of baking, steam plays another role: It helps the starch in the dough's surface to gelatinize, and gelatinization is necessary for a crisp crust. This is how gelatinization works.

    When cold water is added to a starch-containing flour, as when making the dough, the starch granules absorb water and swell. Then, when heated in the presence of enough water (emphasis on enough; see below), the starch granules burst, releasing their gooey, gelatinous contents. That's gelatinization. The gelatinized starch is viscous, with a texture more like molten glass than a liquid, paste or powder. When baked in the oven, it dries down into a crackling, crispy crust similar to cooled glass. But note that gelatinization won't happen unless there is enough water present. That's where the steam comes in. If the dough's surface were to be allowed to dry out before gelatinization takes place, the crust wouldn't end up glassy and crackly. And not incidentally, that glassy surface gives a beautiful luster to the crust, which lesser bakeries attempt to achieve by brushing the loaf with an egg wash.

    There's one more important hurdle for our beleaguered loaf to surmount: gelatinization occurs only above a certain temperature (it differs for different starches), and the surface of the dough must be permitted to reach that temperature.

    As the dough bakes, the oven's hot air, of course, raises the temperature of its surface. But at the same time, water in the dough begins to rise to the surface and vaporize, and vaporization is a cooling process; that is, water absorbs heat as it evaporates. (That's why you feel cold when you come out of a swimming pool.) Thus, while the surface of the dough is absorbing heat from the oven's air, it is losing heat by evaporation. The more its temperature rises from the oven's heat, the faster its water will evaporate, increasing the rate of cooling.

    Eventually, the heating and cooling rates become equal, and the temperature of the surface levels off at a constant value known as the "wet bulb temperature." The problem for our bread is that this temperature is often not high enough to gelatinize the surface starch and the crust will therefore not be crisp.

    Steam (again) to the rescue! Steam in the oven produces a high humidity environment that inhibits the evaporation of water from the surface (your perspiration doesn't evaporate when the humidity is high), hence it squelches the cooling effect and allows the air's heat to prevail.

    The resulting hot surface is beneficial in yet another way. The chemical reactions (the so-called Maillard reactions) that produce browning and "browned flavor" take place only at high temperatures, so while helping the loaf to rise and its crust to become crisp, the steam also helps it brown to a dark golden color.

    Bread at Home

    Unfortunately for us home bakers, an occasional spritz of water into the oven or a shallow pan of boiling water on the bottom shelf can't compete with a commercial steam-injected oven. But don't despair. Many of the artisan bread bakeries operating right here under the red, white and blue make baguettes that are as good as those made under the blue, white and red. These American bakeries, many of whom are members of the Bread Baking Guild of America (, are equipped with steam-injecting ovens and know how to use them.

    In fact, in the 1999 Coupe du Monde de la Boulangerie, an international artisan bread baking competition held in Paris, the specialty breads category (which includes baguettes) was won by a baking team from the United States. In Paris, of all places! Many French faces turned various hues of the tricolor.

    So run to the phone and call all the bread bakeries within a 100-mile radius of where you live and ask them if they bake baguettes in steam ovens. It will be worth the trip. Don't forget to buy an extra one to tear into on the way home. You won't be able to resist.

    Robert L. Wolke ( is professor emeritus of chemistry at the University of Pittsburgh and the author, most recently, of "What Einstein Told His Cook: Kitchen Science Explained" (W. W. Norton, hardcover, $25.95). Send your questions to

    ">[email protected]
  3. thebighat


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    I've been talking to some folks in a Yahoo group about brick ovens and there was some discussion about running a perforated copper pipe into the oven chamber and then pouring water into it so it drips out and makes steam. I've made French bread that would crackle sometimes, and sometimes it won't. I keep a foil pan full of lava rocks on the bottom of the oven at work and pour hot water into it. It makes enough steam to fog my glasses when I open the door. I suspect that really outstanding crackling crust also has a lot to do with the type of fermentation.
  4. panini


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    I can remember our French bread ovens had a type of rebar run down the interior wall of the oven. H20 on them produced the steam. Those were Pavillions sp? I can't remember an actual injection system except for maybe injector type nozzles for the h2o
  5. thebighat


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    I used to use a double rack rotary Hobart that had steam. It apparently blew water over hot steel balls, it certainly made a whooshing noise, and you could get so much moisture in there it would drip off the racks and of course said racks being spotlessly clean the bread never came out with black drippy streaks on it. The only hard crusted breads we made were no-time French and Italian, hardly worth the trouble to make and nothing I would want to get involved with now. The crust would go limp about half an hour after it came out of the oven. I never could figure this out, but the consultant who set the bakery up lavished all kinds of attention on the whole wheat breads, then blew off the hard crusted stuff, and that's what a lot of people wanted. The baguettes had an 18 minute mix on third speed of an 80 qt Hobart, now that's a ride. You could almost set a clock on this mixing cycle for when the dough would just let go. You could hear it happen from the other room. "Oh, must be nine minutes."