Cooking Bread with Steam

Bread dough doesn’t have to be baked. In Chinese cooking, for example, it’s often steamed to make buns. Commercial western-style bakeries also use steam to bake larger loaves with shinier, crisper crusts, an effect home cooks replicate with Dutch ovens. In this post, we’ll compare three methods of cooking bread dough using 花卷 (huājuǎn, literally “flower roll”), a type of Chinese steamed bun speckled with scallions. We’ll compare the traditional steaming method to baking and to baking with steam.

Experiment Overview

Goal: To see and taste differences in texture and appearance in breads cooked in the oven versus the steamer
Recipe: Adapted from Scallion Flower Rolls by Red House Spice
Method: Prepare bread dough and shape the buns. Bake, steam, or steam then bake the buns.
Results: Among the three cooking methods, we noticed differences in
– Crust color
– Crust shine
– Crust texture
– Bun texture
Conclusions: Steaming, baking, or a combination of the two produces buns with different appearances and textures. The best cooking method will depend on the type of bread and your preferences.

Testing Method

Ingredients and Equipment

  • 1 tsp Baker’s Corner active dry yeast
  • 1 tsp Baker’s Corner granulated sugar
  • 130g water at 105°F
  • 2 c (250g) Baker’s Corner bleached all-purpose flour
  • Scallion filling from Red House Spice recipe
  • 6 squares of parchment paper
  • Steamer

Making the buns

  1. Dissolve the yeast and sugar in the water. Let sit until mixture foams, about 5–10 minutes.
  2. Pour the yeast water into the flour and stir until a cohesive dough forms. Cover and rest for 10 minutes.
  3. Knead until dough is smooth and elastic. Cover and let rise for 1 hour until doubled in size. Prepare filling as directed in the meantime.
  4. Divide dough into 6 portions (63g each). Shape the buns using the method from Cooking of Joy and place each bun on a square of parchment paper. Cover and let rise for another 30 minutes. Preheat oven to 410°F and prepare steamer by placing a plate on top of a metal rack in a pan filled with water.
  5. Bake 2 buns at 410°F for 15 minutes, then turn the oven up to 480°F and bake for 3 more minutes (baked). Place the 4 remaining buns on the steamer plate, close the lid, and turn on the heat. Steam for 10 minutes after the water reaches a rolling boil. Remove 2 buns (steamed). Bake the other 2 buns at 480°F for 10 minutes (steamed then baked), until they’re a similar color to the baked buns.
Shaped and ready to cook!

Note: In this experiment, I replicated the effect of baking with steam by first steaming the buns, then putting them in the oven to bake. This method worked best with the equipment I had available, but most recipes use Dutch ovens, a water mister, or a pan of water in the oven. All of these methods use heat to create steam—as long as there is liquid water to vaporize, the environment remains wet. Thus, I felt that my method of steaming then baking the bread was a good substitute for these methods, though if I were to bake an entire batch of buns with steam, I’d just use the oven with a pan of water inside.

Results

To better understand some of these results, I suggest reading through the last few posts about starch, especially the one about flour. At the end of that post, I discuss the effects of steaming bread, which are reflected in these buns.

Crust color

One of the most striking differences among the three types of buns is the color of the crust. While the steamed buns remained pale, both the baked and the steamed then baked buns browned nicely. This reflects a difference in the temperature between the oven and the steamer.

As we discussed previously, browning occurs quickly at high temperatures above 300°F (150°C) as a result of two chemical reactions, both involving sugar. The high heat breaks down sugar molecules into fragments that react with each other in a process called caramelization. The fragments also participate in Maillard reactions with proteins. Both types of reactions produce the brown chemical compounds that add complex flavors to food.

In the steamer, so long as there is still water in the pot, the environment will not surpass water’s boiling point of 212°F (100°C). Any heat we add is taken by the water, not the steam. As a result, the buns at their very hottest can only reach 212°F (100°C), nowhere near the temperatures we need for browning reactions to occur rapidly. Since they can never get hot enough to brown significantly, the steamed buns remain pale.

On the other hand, with enough time in the oven, the buns can reach whatever temperature we set. 410°F (210°C) is plenty hot for browning reactions, so if we bake the buns at least until the crust reaches 300°F (150°C) or so, they begin to brown. We can also use the oven to increase the crust temperature of the steamed buns. Thus, the steamed then baked buns are also brown.

Crust shine

However, the steamed then baked buns do not look exactly like the baked buns. Both types of steamed buns have shinier crusts than the baked buns. This is a result of high humidity in the steamer, where the surfaces of the buns have access to plenty of water as they heat up. This encourages starches to gelatinize. Gelatinized starch forms a thin film—you’ve probably seen it dried onto the edges of a pasta or rice pot. On the buns, the smooth layer reflects light, creating a shiny surface.

In contrast, the dry heat of the oven removes moisture from dough. As a result, water quickly vaporizes from the surface of the baked buns, and there is not sufficient water for starches to gelatinize. Without the film of gelatinized starch, the crusts are dull.

Crust texture

The different moisture levels in the two cooking environments also create differences in the texture of the crust. Because the steamed buns never have a chance to dry out, the outer skin remains soft. In contrast, both types of baked buns have hard and crunchy crusts because they dried in the oven. But compared to the baked buns, the steamed then baked buns have a thinner, crisper crust. The gelatinized starch on the surface of the steamed buns is stretchier than the gluten proteins, so even after the surface cooks, the bun expands a little, stretching the layer of starch in the process. (You may notice that the steamed buns are marginally larger than the baked ones.) Ultimately, this creates a thin skin that, when dried, crisps up nicely. The baked buns, on the other hand, cannot expand once the outer crust is cooked and set. The resulting crust is thicker and more crunchy than crisp.

Bun texture

The insides of the buns also had different textures. Both types of steamed buns were softer, denser, and chewier than the baked buns, which had a looser, drier texture. This difference is again due to the humidity of the steamer. In wet heat, the dough retains more of its moisture, so the cooked bread is wetter and doughier. In fact, many steamed bun recipes contain less water because they retain more moisture. In contrast, the baked buns lose a lot of their moisture in the oven, and the final crumb is drier. In the steamed then baked buns, the interior tasted just as moist as the steamed buns. When these buns were transferred to the oven, the gelatinized starch on the surface formed a waterproof barrier, so water only vaporized from the surface, not from the crumb. Thus, the interior of the steamed then baked buns remained moist despite their time in the oven.

Conclusions

In this experiment, we explored two different ways to cook bread dough. The wet heat of steam gelatinizes starches on the surface of the bread, creating a shiny, thin skin and a moist crumb. The high heat of the oven helps bread dry and brown. We can also combine the two methods to create a thin, crisp crust around a chewy, moist bread. All of these options can produce beautiful loaves, but ultimately, our choice of cooking method depends on the appearance and texture we want the bread to have.



References

Corriher, S. O. Bakewise; Scribner: New York, 2008.

Corriher, S. O. Cookwise, 1st ed.; William Morrow and Company, Inc.: New York, 1997.

Figoni, P. How Baking Works, 3rd ed.; John Wiley & Sons, Inc.: Hoboken, 2011.

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