Open Baking Sourdough

Dutch Oven vs Open Bake

When starting out with sourdough the majority of bakers opt to use a dutch oven to create steam during the first part of a loafs bake. This is a wonderful method and how I did so until I needed to expand the volume of what my home kitchen could produce when I decided to start my own micro bakery. If an individual needs to make more then two loaves at a time; odds are that the need to ditch the dutch oven will become almost non negotiable. Also, being able to open bake in your oven will allow you to do much more than a dutch oven such as a full sized baguettes.

The Problem

Most home ovens both gas and electric are designed to vent excess steam. Our job as bakers is to come up with an effective method to make more steam inside the oven than it can vent. We do this to achieve the maximum amount of oven spring out of our loaves. Doing so will produce a loaf that is open and airy with a delicate crust that is almost cracker like in texture. The steam delays crust formation until the dough has had a chance to rise completely. In addition, steam also gelatinizes the starch present in the flour on the surface of the loaf and helps to yield a bubbly and color rich crust.

The Solution to Steam

Firstly, if the oven has a convection setting, turn that off for the first half of the bake. Convection uses a fan to circulate air inside the oven. This behavior works very well for ensuring an even bake. However, this is the enemy of trapping steam inside. It will accelerate the rate at which the steam will dissipate.

When I initially started trying to come up with ways to mimic a bread oven at home my first thought was a mechanism that would cover my steam vent to trap it in. This may have worked for the steam. But, in my research I found that home oven are designed to hold their temperature in part using these vents, so, that was out.

The next thing that I tried was using the old pan of water trick. This had little to no impact on the outcome of my final bakes. The loaves produced via this method where under sprung and ashy. Then I had remembered that some people used ice cubes instead of boiling water in their trays. The thought behind this being that the melting ice will vaporize better on contact with the hot surface and produce better steam. This was worse than the boiling water in all of my testing. I found that if I used a small enough portion of ice such that it doesn’t cool the pans surface down too much, it will all evaporate within the first few minutes leaving me with no moisture left to aid in oven spring. In contrast, if you used an amount of ice sufficient to equal the amount of boiling water used, your pan would become so cool that it wouldn’t be able to regain it’s temperature to turn the resulting water to steam before the first half of the bake was done.

The solution came when I found a cast iron loaf pan on sale one day while shopping. I bought it thinking that it would help me in this journey because it would be durable enough to stand up to years of abuse in my oven as a steam tray. I had also been reading about how some where pouring boiling water over lava rocks in a cast iron skillet placed in the bottom of the oven as a steaming mechanism. I had initially dismissed this when I had first head about it because I believed the claim that the increased surface area for water to evaporate from the porous rocks would not make a difference. Also, I thought that if there was such a benefit that it would be minute and that the oven would just vent it anyway. However, I decided to pick up a bag to test it. After all, I had already come this far. Boy was I wrong! The first time I tried it I was running back and forth from the oven checking every 5 minutes watching the loaf spring to life and telling my wife how happy I was that I finally got the results I had been chasing! The loaf was one of the best I had ever made up that point. I had found my answer.

Stone vs Steel

The next thing to figure out is what to be on. Standard half sheet trays that fit inside of a home oven are a poor choice become they do not retain heat very well and often don’t have enough thermal conductivity with the loaf to give us the desired results, so, they’re out. That leaves baking stones and baking steels. Either will be sufficient for this purpose. However, if baking more than two loaves at a time is ever a possibility then I would suggest going with the baking steel. In my oven I have two 14”x20” baking steels. This allows me to fit up to eight 800g loaves in my oven at a time. Even though I am loading the loaves onto the steel at 34° directly from the fridge, the impact to the temperature if the steel remains minimal. The only downside I have noted about steel is that if using two, the loaves on the bottom rack can burn on the bottom before the crust is browned on top. The combat this, when opening the oven halfway through the bake to vent the steam I move the loaves from bottom to top and top to bottom to finish baking.

Whichever is used to bake, there will need to be sufficient means to load the loaves onto the baking surface. I use a thin sheet to plywood cut to the same size as my baking surface to act as a peel. I cover that with a sheet of parchment paper and then turn my loaves out onto that, one in each corner. I use the weight of the loaves to hold the paper in place while I trim it to the same size as the wood sheet. Doing this allows me to take all the guess work out of positioning my loaves optimally so they have enough space to spread out without touching in the oven. Before I was able to accurately turn my loaf out where I wanted it on the board I would flour their bottoms with rice flour before removing them from the banneton so that I could easily slide them into position. Then just slide them off onto the steel in the oven.

Other Observations

A few other observations I made while figuring this out is that when baking six to eight loaves in one oven, it’s almost unnecessary to add additional steam. Just like a dutch oven traps steam, when you have 4.8kgs+ of dough baking at once it will release enough steam to negate the need to add more. This can actually work against you if you have your temperature up too high. Typically in most recipes you see they will say to start the oven at 500°F and then drop the temperature down when you load it, usually to around 485°F. This is too hot for this setup. It just isn’t necessary. The bottoms of the loaves will burn and still be blonde on top. This is why my recipe calls for preheating to 475°F and remaining there. The steel will retain enough heat for sufficient oven spring.

The oven will undoubtedly have hot and cold spots. To combat this, I also spin my loaves when I shuffle the the rack they are on at the halfway point. The spinning can be avoided by turning on convection at this stage if the oven has it. A goose neck kettle can be a worthwhile investment for pouring the water into the steam tray. It is much easier to pour the water where you want it to go and maintain a good distance with your arm to avoid burns. There will be a flash of steam initially that can be quite hot.