Gluten is a word in action these days, popping up on labels at the grocery store, in the news, and all over the Internet. Many of us have even chosen to eliminate gluten from our diets — but I have to ask: Do you really know what gluten is?
Here's a guide to the science of gluten and what that little word actually means.
Gluten Is Actually a Network of Proteins
A bread dough that is just mixed, and that you haven't kneaded at all, looks completely different after you've slaved over it for 10 minutes. That's because the gluten network formed. There are two major proteins that make up that network: glutenin and gliadin. Glutenin provides strength and elasticity to baked goods, while gliadin provides plasticity.
While you can find both glutenin and gliadin proteins in dry wheat flours, the gluten network doesn't yet exist. Glutenin and gliadin can only come together to form the structured gluten network when they come into contact with water, and to form, the network also needs lots of mixing and/or lots of time (think of those no-knead bread recipes, for which the dough has to sit for more than 12 hours).
The process of kneading helps rearrange, stretch, and elongate glutenin and gliadin until they have arranged into an ordered, structured, extensive network that can be pulled and stretched without tearing. Consequently, that ball of dough goes from a shaggy, messy lump, to a smooth, elastic ball.
The Gluten Network Adds Structure to Baked Goods
The gluten network plays an essential structural role in baked goods, which is why gluten-free baking represents such a great challenge. The gluten network can expand and stretch a certain amount without tearing, allowing baked goods to rise during proofing (for breads) and the early-stage of baking (for breads and cakes), trapping air bubbles within before drying and setting in place.
The gluten network also makes breads and cakes a little more cohesive, so when you cut into them, they don't just crumble and fall apart completely. Once baked through, the gluten network provides breads and cakes their ability to bounce when pressed lightly.
Sometimes You Want a Lot of Gluten, And Sometimes You Don't
We tend to assume bread requires a lot of gluten protein, but that's not entirely true — it depends on the bread. For example, artisanal breads — with an open crumb and lots of big holes — are often made from a lower-gluten flour than a white sandwich bread, with its tiny bubbles and finer crumb. As the bread expands, tearing occurs because there isn't enough of a network to hold the tiny bubbles of gas; the small bubbles merge into larger pockets within the bread before setting, leading to a bread with lots of big holes.
On the other hand, some baked goods depend on other structure builders, like eggs in sponge cakes, instead of relying exclusively on gluten. These may have much less flour than other traditional baked goods. In cookies, you don't want too much gluten to form because that gluten will lead to tougher cookies.
And for pie and tart doughs, too much gluten formation will make rolling out your dough more difficult because it will be too elastic, and gluten formation can also contribute to shrinking if it's blind-baked. Best to avoid overworking the dough or adding too much liquid, but you can't get away in most cases with adding no liquid to pie crusts because you want a small amount of gluten to form (and also for hydrated starch molecules to act as glue) so the pie crust and cookies hold together and don't crumble or fall apart when served.
I'd love to hear from you: Did you already know what gluten is? If not, did this post help clear up any confusion or change your opinion about gluten?