Baking Bread with Steam
from https://www.kingarthurbaking.com/

How steam can transform your bread from dull to dazzling. Have you ever loaded your perfectly risen artisan bread into the oven, only to discover a dull, constricted loaf at the end of the bake? How do artisan bakeries achieve that lovely golden, crisp, shiny crust? Baking bread with steam is the key.

Why it's important to bake bread with steam

Steam is critical for achieving crusty loaves of bread, for reasons both functional and aesthetic. If you bake bread in a dry oven, the crust quickly sets and dries, impeding the ability of the dough to expand to its full potential, leading to loaves with a denser crumb. But if you were to bake an identical loaf, introducing steam at the start of the bake, the crust remains moist, and the loaf is able to stretch and expand before the crust sets, resulting in a better crumb structure. Additionally, even if you score your bread properly, those cuts will not expand in a dry oven; you need steam for that.

Besides functionality, there are aesthetic reasons to add steam to the oven when baking. Steam helps gelatinize sugars on the exterior of the loaf, resulting in better browning, and a shinier (and also thinner and crispier) crust.

How can we get results like this at home?

Bakeries have steam-injected ovens that handle this easily; in a home oven, it's not so simple, requiring a more DIY approach.

Today we're going to test different home methods of adding steam in bread baking. Our test bread is the Pain Au Levain recipe used in our Baking School. This lovely sourdough bread has a mild flavor and a wonderfully open crumb. Pain Au Levain is the perfect guinea pig for our steam tests. We can first admire the loaves baked in class, utilizing a professional steam injection oven. Next, we'll use the same recipe at home to test various baking and steaming methods. Which home steaming method will bring us closest to professional oven results?

A brief note about scoring (aka "slashing")

Before we get too steamy, let's take a moment to consider the importance of scoring your bread before baking. Those cuts in your bread aren't just decorative! Scoring the loaf provides a strategic vent to release fermentation gases during baking. Good scoring, along with proper steaming, allows your loaf to open up fully. Without scoring your loaf is likely to burst open at weak spots and end up oddly shaped and constricted.

Method #1: Baking bread with steam using a spray bottle

The simplest method of adding steam to your oven is to spray the loaf with warm water prior to putting it into the oven. Spray the oven once the bread is loaded, and then again about 5 minutes into the bake. Unfortunately, this method doesn’t offer much moisture, and the effects on the bread are minimal.

Method #2: Baking bread with steam using a cast iron pan

In class, our instructor illustrated method #2. She loaded the loaf onto the preheated stone and then poured about 1 cup of boiling water into a preheated cast iron frying pan on the shelf below. This method works quite well.

Method #3: Baking bread with steam using a metal bowl

If you want to enhance the effect of method #2, a large metal bowl can be placed over the loaf to trap the steam and keep it close to the surface of the bread during the oven-spring period. This is part of the reason steam injection ovens get such great results; the individual "decks" of the oven aren't very high, keeping the steam where it's needed — on the surface of the loaf.

Load your loaf onto the preheated stone and then place the bowl over the loaf, with the front of the bowl overhanging the stone and leaving a gap that lines up with the preheated cast iron frying pan below.

Pour about 1/2 cup boiling water into the frying pan and shut the door. Remove the bowl 15 minutes later and allow the bread to finish baking in a dry oven. A butter knife comes in handy to lift the hot bowl, which will be hard to grab with oven mitts.

If steam is so great, why finish in a dry oven?

Steam is vital during the oven-spring period so that the surface of the loaf remains moist and expands easily. However, once the yeast has died and the loaf is set, moisture is no longer a friend to your bread. Too much moisture throughout the bake can lead to a thick, rubbery crust.

Method #4: Baking bread with steam using a Dutch oven

A Dutch oven or cloche also works to keep the moisture given off by the bread during baking close to the surface of the loaf, allowing for the same kind of expansion and shiny, golden crust. Remove the lid after 20 minutes of baking.

Never fear, though, if you don't have a pot suitable for preheating empty (or don't like messing with a very hot pot), you can still get great results baking in your Dutch oven. Again, it’s important to remove the lid and allow the bread to continue baking in a dry oven after the loaf is set (remove the lid after 25 minutes in a preheated oven).

Let's compare our results

The loaf on the left was steamed with method #1 (spray bottle). This loaf failed to open properly where I scored it, and the crust is dull in color. Notice how the crumb structure is relatively dense, in comparison with the other loaves? It will still be a delicious loaf of bread, but more steam would have made it even better.

The loaf in the center was steamed with method #2 (cast iron pan). It opened up beautifully and has a lovely brown crust, although not quite as shiny as loaf #3.

The last loaf was baked with method #3 (cast iron pan + metal bowl). See how shiny and blistery the crust is, and how open the crumb?

Both this loaf and the loaf baked in the Dutch oven were refrigerated overnight in their shaped form before being baked the next day. This added step contributes to a more blistery crust, as well as more sour flavor.