Why bakers steam their bread (and how you can too)

Rye loaves and rolls, baked with and without steam

One of the differences between home and professional bakers is that commercial bakeries have ovens which release copious quantities of steam on demand. I got a lesson this week in why steam is important, when I took a Sourdough Rye class from Jeffrey Hamelman at King Arthur Flour and one of the ovens failed to release its steam on schedule.

You can see the result in this picture. There are two beautiful dark rye loaves which were made with a similar formula and steamed successfully. The round and oval rolls were composed from leftover dough. They’re pale and many of them are misshapen and while they tasted okay, they’re not a product you could serve with pride, let alone put out for sale if you were a commercial bakery.

Steam is released at the beginning of the bake, when the bread is coming up to temperature and commencing its “oven spring”. It’s quite typical for volume to double or triple in the first five minutes of the bake. Steaming the oven keeps the dough surface moist and flexible so the bread will have room to expand. When it’s up to temperature, the residual moisture provides a medium for caramelization to produce an attractively brown and crunchy crust.

The failed rye rolls expanded in spite of a stiffening crust, so they pooched out wherever there was a weak spot from the shaping. And they came out pale brown, not dark gold, because they missed out on the caramelization.

So is there hope for the home baker who wants to turn out great looking breads with the use of steam? Yes. If you use the kettle method you’re already doing it because the moisture from the dough itself is trapped inside the dutch oven and turns into steam during the first few minutes of the bake (after which you remove the lid to avoid pale and soggy bread). I’ve heard good reports of a similar tactic using a large stainless steel bowl covering a pizza round, and batards steamed inside an oval roaster.

If you’re cooking baguettes or another bread that bakes in the open oven, you have a bigger challenge. The strategy that works best for me is to a/take a big old beat up cast iron pan and optionally add a few links of chain, lava rocks, ball bearings or other noncombustible items to increase the surface area; b/preheat the pan on the floor of the oven to 500 degrees; c/pour in about 1/3 cup of water just after loading the bread and quickly close the oven door; d/pour in another 1/3 cup of water after two minutes (by which time the first water should be completely evaporated) and again quickly close the door; then bake as usual. [This description has been updated.]

A few cautions. Be sure you’re wearing gloves and protecting your face when you pour the water because steam can burn you, badly. Keep the water away from the glass in the oven door or it might crack. And don’t use too much water because then it will just puddle in the bottom of the pan instead of turning into steam.

You might also try squirting blasts of water at the oven walls with a good strong garden type sprayer, and pouring in more water after you load the bread, when the first steam has dissipated. All this will give you steam, and the question is whether it’s good enough in your oven for the results you want. Let me know how it goes.

UPDATE: Years later, I have figured out a much better strategy than any of the above. Read about it here.