Cooking and Baking in a Woodfired Pizza Oven

Before we can cook any food inside the dome-shaped Pizza oven, we need to burn wood inside to great heat. Therefore cooking and baking are done through the physics of heat transfer. Heat transfer refers to the energy given from one object (hotter) to another (colder) to heat it.

We can distinguish these types of heat transfer:

1. Radiant heat from a direct source (fire or ember).
2. Radiant heat is released from the oven’s heated walls; they accumulated energy during the heat-up period (heat retention). Thermal radiation is a form of heat transfer caused by electromagnetic radiation emitted from the heat source that carries energy to the surrounding. This energy is absorbed by close-by objects increasing their particles’ average kinetic energy and, therefore, their temperature.
3. Convection heat from a direct source (fire or ember). Convection is heat transfer by the mass movement of hot air from the heat source, carrying energy to the colder side. Hot air is lighter than cold air and travels upwards along with the dome ceiling while the cooled down air travels back to the heat source, causing a convection circle.
4. Conduction from the bottom plates. The inside stored energy has been accumulated during the heat-up period (heat retention). Conduction is the transfer of heat from a hot object to a cold object in direct contact. Heat retention refers to the amount of heat an object or material can store overtime. 

Based on these explanations we can discuss 4 cooking/baking techniques:

1. Typical Pizza Baking ( 400C/750 F) hottest temperature, with direct heat (fire on one side).
2. Roasting (600 F to 450 F) (small direct fire or a pile of ember on one side)
3. Grilling over or cooking in Ember (hot, direct heat over hot ember only, no fire))
4. Baking/cooking (520- 350 F) using heat retention without a direct heat source

Typical Pizza Baking (400C/ 750 F)

In a typical Pizza-baking scenario, we will be fully heating the oven to reach high wall temperatures (800 -900F) and a bottom temperature (floor tile in the center of the oven, Heart) of 800- 750F. Normally this point is reached when the inside of the oven has turned white. What does this mean? Remember, to produce heat; we must burn the wood inside our baking chamber. Below 250F, besides water, organic substances/gasses escape from the wood and burn, forming creosote and soot at the dome walls. To avoid a large build-up of the tarry creosote, we chose wood that has been dried for at least 1 year. Soot is a fine black or dark brown powder that forms a thin black layer on the dome. When the oven reaches a wall temperature of 900 F, the black layer burns away, revealing the clean wall. This is the sign that the oven is ready for use. At this stage, you let larger logs burn out to distribute the ember evenly on the bottom floor for 30 min. This stage is called “soaking,” a process that transfers heat to the bottom tiles and even the floor tiles’ temperature.

Now use your utensils and move all the ember to one side of the dome. I prefer the left to have the right side free for baking (about 2/3 of the total area). Then I place an andiron directly on the ember to place small logs onto it for setting quickly a fast. A furious fire rages along with the dome ceiling to the right side (convection) to cook the pizzas’ toppings.

With a heart temperature of 752 F, any pizza will receive direct conduction heat and cook in 30 to 60 seconds. With a round-shaped turning peel (mot important utensil), you need to monitor the pizza bottom while turning periodically from the radiant heat of the fire away (otherwise, you have one side burned). Keep in mind that the pizza “sucked heat from the area it was sitting on, and you should not move it to another title that is much hotter. Turn the pizza around the same area you placed it on. Note: It is a good idea to measure with a laser thermometer the zones in the oven. In a “cooler” Zone, you can drop a calzone that requires a longer cooking time. Also, keep in mind if you cook closer to a wall, you get radiant heat that may brown or burn this side faster.

Roasting (600 F to 450 F)

This cooking technique uses a small fire or pile of ember. Food is placed on a grill and roasted by heat transfer from the side and needs, therefore, must be occasionally turned—a good method of bigger pieces of meat.

Grilling over or cooking in Ember

Cooking over ember is similar to cooking on a charcoal grill, where radiant heat is transferred to the food. Additionally, some radiant heat comes from the walls. Ideally, you can use a short-legged grill or improvise by putting a metal grid on a few fire bricks—best for meat and charring vegetables. Root-vegetables can also be put directly into the ember.

Baking/cooking (520- 350 F)

One of the big advantages of these brick or refractory-concrete ovens is the long heat retention of these ovens. This feature is used for cooking and baking without an additional energy source. As you can see from the plot, the lighter refractory Concrete oven loses heat much faster than the heavy brick oven. This means that the available cooking time is shorter. Also, you need to consider the cooldown time to reach the desired temperature. With my oven, it takes me at least 6 hours to get to the upper bread baking temperatures (300C /572 F), which is too high for big loaves. Depending on the type of bread, I bake bigger loaves around 270 – 250 C / 520 -482 F.

Once you have done all the hot temperature baking and cooking you let the fire is burned out. Now you distribute the ember inside the chamber and close the door to let the heat soak in again. This will serve two purposes to bring heat into the bottom and to even out the temperature across the area. If you are done for the day then you can leave the ember inside with a closed door. This way the oven will still have some heat for a little while longer and cool down slower. The effect is minimal as no oxygen is provided and the burning of the charcoal will stop. I am mentioning this fact because cooling to the desired baking temperature can cause a problem. Let me explain this with the plot.

After Pizza and hot cooking, and soaking of the floor tiles, you are in the 400 C range. My oven (yellow) reaches about 6 to 8 h in the desired temperature range of 260 – 250C. We had a pizza evening, and I closed the oven around 8 pm with the ember inside. At 8 am, the temperature is around 220 C, too low for baguettes and some other loves of bread. I would have to get up at baker’s hours to clean up the oven at 4 am and loaded. Compare this to a brick oven. At 8 am the temperature is around 300C and you can wait even a little long. Now, this does not necessarily mean you need to buy and built a brick oven. There are several options and depend on your priorities, which is for my bread baking and cooking.

1. Option; Full oven heat early: Usually is already fully loaded and ready to fire up. I fire up around 9 pm. By 11 am I will be ready for hot temperature baking. There is no rush, and it is all very relaxing. I start baking some “blind” pizzas, meaning without toppings, which we will conveniently freeze. Then bake some of the Rotis and for lunch some pizzas. As the temperature drops, I will bake some thicker Pizza types of bread from calzone, Georgian, Turkish, Greek, and Indian-filled flatbreads on the cooler side. Also, I can roast some meat and much more. After I am done, the glowing ember will be distributed, and the door will be closed for soaking it up for 30 min. Then I remove all the ember and scoop it in a metal can, quickly brush out the floor tiles and give them a brief cleaning with a moist mope. Then I close the door again and let it cool down. Now I have 6 hours to prepare. In between, I check the temperature. Around 300 C, I mopped out the oven again add a steel pot with hot water and load small baguettes, which bake quickly 8 to 10 min. Small buns and others can be baked too but not big loaves.

Figure: Heat Retention of Brick oven (blue) vs. Refractory Concrete Oven (orange) and not fully heated oven (yellow). X-axis: Time (min), Y-axis: Temperature (C) The heavier brick oven retains the heat for a much longer time than the lighter cast oven. Obviously, the heat decay depends on the type of material, insulation, and auxiliary weather conditions.

2. Option, not fully heated oven (see figure series 3): Everyone who has built these ovens has to cure these ovens to heat. Heating smaller amounts of wood do this. Over 2 to 3 hours, these ovens get quite hot. Again we can use the amount of shoot in the oven to indicate the oven’s reediness. Here we heat the initial load, but we don’t add later thicker loads of logs. The goal is to keep the flames inside the dome and not blasting out through the chimney. Continue to burn wood until the black shoot on the dome ceiling and half of the dome wall vanishes. At this point, prep for pizza baking as before with a fire on the side. This works well for a few pizzas, flatbreads, Tarte flambee, and pita bread. After you have finished, you need to distribute the ember for a 30 heat soak with the door closed. Continue as described before. The heat needs to be monitored as it is decreasing much faster. Still, it is long enough for baking and cooking. So if you finished Pizza at 6 pm, you could bake small baguettes at 8 pm and bread by 8:30 pm and bake till 10 pm whatever you want and later pumpernickel bread overnight.

3. Option fully heated and reheat in the morning. This option will be explored and reported later.