All things being equal

[Lester]

With all things being equal, the amount of heat, the temperature, the incrediants; why do the different heating methods make the food have different textures and flavors. Why does the same pizza cooked in a gas oven taste and feel different than a pizza cooked at the same temperature in a coal or wood oven? What makes each heat source have its own unique signature if everything else is the same? Inquiring minds want to know...

[jengineer]

dang now you gonna make me buy another book from Robert L. Wolke

A few years ago I was going on a long boring plane ride and needed something to entertain me. I have a tendancy to devour books so i try to stay away from book mongers but I said to myself hey gotta feed the beast. Unfortunately I had no idea what would amuse me, vey bad sign usually has a high $$ associated with it. Well a book title "What Einstein Told His Cook" grabbed my attention, well really it was the brand new Bunsen burner.

It does not quite answer your question but it does tell you the differences between coal and gas BBqs and if you buy gas what the real minimum BTU you sould buy and why.

http://www.wwnorton.com/catalog/spring02/001183.htm
partial quote
In (the chapter titled) "Fire and Ice" you will learn how to buy a range and the difference between charcoal and gas for grilling.

So Now I have jumped onto his web page and found this tidbit, it came out a year ago and no I don't have it....yet
http://www.robertwolke.com/cooktwo.html
and I quote -
Are brick-oven pizzas really better?
Yes, because brick and stone have high heat capacity and high emissivity—they retain a consistent level of heat and absorb far less infrared radiation than metal ovens. Because infrared radiation doesn’t penetrate beyond the surface of materials, more infrared radiation striking the pizza dough results in better browning and crisping of its surface.

[Lester]

So Now I have jumped onto his web page and found this tidbit, it came out a year ago and no I don't have it....yet
http://www.robertwolke.com/cooktwo.html
and I quote -
Are brick-oven pizzas really better?
Yes, because brick and stone have high heat capacity and high emissivity?they retain a consistent level of heat and absorb far less infrared radiation than metal ovens. Because infrared radiation doesn?t penetrate beyond the surface of materials, more infrared radiation striking the pizza dough results in better browning and crisping of its surface.

That is an interesting piece to the puzzle, but only adds to the question: Why does a brick oven that is fired by wood produce food that is different than food produced in a brick oven fired by gas or coal? I get the stone/brick part, but am very curious about they heat and the 'whys'.

[james]

A few ideas on why brick oven cook so well

Hey Lester,

The science of how ovens work and how food cooks is interesting, and I am looking forward to learning more. From a practical, hands-on perspetive, I can add a few things from what I have experienced.

1. Any refractory oven cook better than steel ovens with either an electric coil, gas burner or a convection fan. Retained heat ovens absorb the moisture and heat from a wood-fire and reflect fire back into the oven chamber. The heat in a retained heat masonry oven is moist and gentle, compared with the dry of a modern oven. You can put your hand in a wood fired oven and actually "feel" the moisture. Retained heat ovens can cook at a higher temperature than a modern oven, without burning or drying out your food. Consider hearth bread. If you take two loaves of bread made side by side, and put one in a brick oven at 550F, and the other in a modern convection oven at 450F -- the exact same dough will produce a beautiful hearth loaf in the brick oven, with a crisp crust and a well developed, yet moist crumb. You can see the extended strands of dough in the crumb, with well formed holes that result from the oven spring of a moist oven. The crust of the loaf shows the carmelized sugars that only form at higher temperatures.

If you bake that same dough at a high temperature in a conventional oven, it will simply burn. That same dough will make a very ordinary, even bad, loaf of bread in a conventional oven. No oven spring; no crust; no crumb texture; no holes.

Now, apply this same logic to gnocchi, lasagna, a roast, grill or a vegetable gratin. You get a nice, light, moist dish -- and you can see the difference between a brick oven version and a conventional oven version. Make two lasagne, and cook them in the two ovens, and you can definitely see the differnce.

2. With fire-in-the-oven cooking, a brick oven cooks three ways. You get conduction from the cooking floor, where moisture in the dough is converted to steam -- essential for great pizza or bread. You get reflective heat from the dome. The fire in the oven reflects heat evenly down on the cooking floor, and on your pizza (or roast or appetizer or grill pan). The shape of the dome and the round floor are essential for this type of cooking -- you simply cannot do this with a rectagular bread oven. The oven is one of the elements what makes Italian pizza the authentic product that it is. Finally, your wood-fired oven draws in cold air through the bottom of the opening and exhausts hot air out the top half. Inside the oven, hot air moves, creating natural convection. This helps all the food in your oven cook nicely and evenly. The rectangular bread oven is really bad at this, and does not provide even heat on the cooking floor.

My experience is that is it almost impossible to make really good pizza in a brick bread oven, and this extends to all fire-in-the-oven cooking.

3. Wood-fired dome ovens give a definitely better flavor and texture than gas-fired dome ovens. I think this is true for a couple of reasons. First, wood-fired ovens tend to cook hotter. It's easy to keep a Forno Bravo oven at 750F -- they cook at that temperature all day using wood. Most of the gas-fired ovens I have seen cook between 500-650F, which just isn't the same. Gas is good for the San Francisco Zoo, where they cook frozen pizzas in a gas dome oven at 500F (5-7 minutes each), but not for you. Second, wood-fired ovens breath better, making a better, and ligher pizza that cooks in about two minutes. The wood-fired flame laps further in the dome than the gas flame, and it's hotter -- giving you that authentic dark brown crust and melted cheese. It's the point where dough, tomato, mozzarella and olive oil "fuse" that makes great pizza and you can't do it in a gas oven. Last, wood gives you a little nice, smokey flavor from the wood fire. It isn't huge, but you can taste it.

It's definitely easier to cook in a 500F gas dome oven, but it really isn't the same thing -- apples and oranges.

Whadya think?
James

[CanuckJim]

Analysis

James,

A very thorough and well thought out analysis. I agree entirely with what you've said about the differences between wood and gas. From a bread baking point of view, the chief advantages are: oven spring, moisture and caramelization. You can spot a gas fired oven hearth loaf from fifty feet because the crust is browned but not caramelized. Apples and oranges indeed.

Jim

[Muti]

great info!

Thanks a lot James!

Sincerely appreciated!

[THICKCRUST]

Re: All things being equal

Never hurts to put a frozen pizza in a brick oven for a for my girlfriend

Saves me lots of time,

Then again....I miss my blonde girlfriend, telling her microware frozen pizza was brick oven was no problem

[stuart]

Re: All things being equal

Though I'm not cooking with a pizza oven...yet, I can attest to the superior cooking in a wood fired, ceramic grill/smoker over gas fired metal grill.

I've used a komodo style smoke/grill for almost 10 years, fired with lump charcoal. My friends have always raved about the flavor and moist qualities of the meat. I make pizza on it too, a little difficult as the heat source is under the pie, but worth the effort until I build the real pizza oven.

Last August we moved into a new house, which was equipped with an outdoor kitchen, including a 48-inch DCS grill. Friends with lesser grills all oooh'd and ahhh'd over the thing. It took me 3 months to even fire it up when curiosity finally got the best of me. No comparison. I've used the gas job 3 times in 8 months, while the Big Green Egg gets used each weekend or more.

I'm in the design phase of remodeling the kitchen to accommodate the pizza oven, and while the gas grill will be retained, it will only be for those times when we want to grill some dogs for the kids and need the ease of twisting a knob.

[galaxy51]

Re: Analysis

Jim, Could you try to explain the difference between browned and caramelized bread? Doesn't caramelized refer to a darkening of sugars? Thanks, Cory
"You can spot a gas fired oven hearth loaf from fifty feet because the crust is browned but not caramelized. Apples and oranges indeed."

[CanuckJim]

Re: All things being equal

Galaxy,

This is easier to show than to explain. A browned crust is just that, brown and dry. Caramelization is mahogany brown and shiny, like the top of a creme brulee. On my loaves, it usually occurs in a ring (I use banneton) just above the bottom of the loaf. Sometimes, too, you can see it on the upper portion of the loaf and on the flap of the grigne. The flavor enhancement is just what you would expect from caramelized grain sugars.

Jim

[LLArts]

Re: All things being equal

James -

I read with great interest your analysis of wood vs. gas, etc. Being a "newbie" and just started out on this forum (and still in "dream stage" for planning an oven...) I was wondering about air supply to the dome oven/fire.

Have you any experience or thoughts about putting a variable air inlet at the side of the dome - flush to the oven floor, to get air direct to the fire? The reason I ask, is that I think (speculating now) that if you cook not only at the opposite side (of the fire) in the dome, but also in-line with the opening, you would get a cold-air wash over the food.
Also with a side-inlet, you could block the front opening and still have the fire going, possibly maintaining higher heat with less wood consumed (assuming that you choke the air properly so you don't get a blast furnace)???

Any thoughts/comments?

/Lars

[lwood]

Re: All things being equal

Wow, I feel like i have a masters in wood fired bread making. And "emissivity" my gosh, I haven't heard that word since chem eng heat transfer class, had to go back and look it up.

That's a lot to digest, but I can't wait to experience it for myself, thanks.
John

[dmun]

Re: All things being equal

Have you any experience or thoughts about putting a variable air inlet at the side of the dome - flush to the oven floor, to get air direct to the fire?

I can't think of a better way to blow ash all over your food. It's not generally considered a good idea to have ANY holes inside your dome at all: No ash slots, no air intakes, no vents from auxiliary fireplaces or smokers, no chimneys at the top of the dome. You're trying to build a highly insulated brick chamber to collect, reflect, and concentrate heat. Poking holes in it is counterproductive.

[lwalper]

Re: All things being equal

I don't know, but it seems to me that food cooked in a wood fired oven comes with mostly anectodotal and subjective evidence that "it's better"—and I don't doubt it one bit. The placebo effect is very real. There may also be something to the slightly smoke enhanced flavor of baking with a fire actually buring in the cooking space. If the fire is extinguished/removed is there a flavor/baking difference between "white" ovens and "black" ovens?—dome vs. tunnel (with and without retained fires).

The notion that there is more "humidity" in a WFO (or masonry vs. steel) is probably bunk based more on what "I think" is happening than on science.

I'm no engineer, but it's my understanding that (as a general rule of thumb) relative humidity (assuming everything else remains the same - including vessel pressure and the preservation of absolute moisture) will drop by a factor of two (2) for every 20?F rise in temperature. With that in mind, an oven operating at 700?F has a relative humidity bordering on zero, whether the oven is constructed of brick or steel. I don't think I recall seeing anyone measure the actual air temperature in the oven? All we typically get are surface temps and "practice till you figure out how your oven actually performs."

Since I'm in the early (very early) stages of constuction and all I've really done is read and tried to digest the available info, all this may just be blowing through my hat. Ahh well, construction pics to come—when the weather warms up a bit (it's too cold to work concrete).