BiologyChemistryFeaturedFood

Baking Gluten-Free Bread, Part 1

I think we can all agree that bread (and its many cousins like pizza dough and bagels) is pretty delicious and amazing. Consequently, people who avoid gluten in their diets can miss out on some pretty tasty foods. But this does not have to be so!

This post was generously sponsored by Donnie as part of the SkepchickCON 2013 fundraiser. Thank you, Donnie!

While I’m not going to get into the science behind why people with Celiac disease and other conditions have trouble processing gluten, I am going to look at the science behind gluten-free bread.

What is gluten?

You may be wondering why gluten-free baking is a challenge in the first place. To understand why, you need to understand the role that the missing element plays in traditional, gluten-full bread.

Gluten molecule tattoo

Gluten molecule tattoo. Source: http://sine-beena.tumblr.com/

Gluten is a combination of wheat proteins called glutenin that forms when water is introduced. Gluten molecules look something like springs, with coils and kinks, and their structure means that these molecules are both plastic and elastic, both changing in response to added pressure and also springing back into place when that pressure is relieved. In the case of bread, that pressure is applied by yeast, a microscopic single-celled fungus. Specifically, the yeasts consume and metabolize sugars in the dough and produce carbon dioxide and alcohol* as a by-product.

That’s right: bread is made delicious because of fungus farts. You’re welcome.

When this gas is expelled, it becomes trapped in the dough thanks to the springy nature of gluten–the dough stretches and bubbles form to accommodate the gas. As these bubbles accumulate, the bread rises, and all of the air pockets inside mean it will be soft and fluffy after baking. Without gluten, the bubbles don’t form, air doesn’t get trapped, and the bread can’t rise. It will be dense and likely dry, because these air pockets also trap moisture during baking.

And so, we come to one of the keys of gluten-free baking: replacing the gluten with something else that can make the dough similarly stretchy.

Gluten-Free Baking

Gluten-free flour can technically be any flour that is not made from wheat. You can find flours made from a wide range of other grains, grasses, tubers, legumes, and nuts: oats, sorghum, buckwheat, corn, teff, arrowroot, potato, garbanzo, fava, tapioca, rice, almond… Different flours will contribute different textures and flavors to the final product. All-purpose gluten-free flours contain some combination of these alternative flours.

xanthan gumThe most common gluten substitutes are xanthan gum (a bacteria-produced polysaccharide) and guar gum (the ground endosperm of guar beans). Psyllium husks and eggs can also help to bind the dough and retain moisture.

One advantage that gluten-free dough has over traditional bread dough is that you can’t “overwork” it. Remember how gluten molecules are like springs? When you knead bread you stretch out those springs. A certain amount of this is needed to unfold and align these molecules and form the bonds that will let those bubbles form. However, just as if you stretch a metal coil too far or too many times you can wear it out and it loses its springiness–the same thing happens with gluten molecules. Knead it too much and you won’t be able to trap any fungus farts. Gluten-free dough doesn’t have this problem, so can use an electric mixer without fear of breaking down the gluten network.

Check out Part 2: my experiences baking gluten-free bread!

*Both the CO2 and the alcohol end up getting expelled from the bread by the heat of baking. So no, bread will not get you drunk.

Sources:

On Food and Cooking, by Harold McGee
Gluten-Free Baking Fact Sheet, from Colorado State University
Top Ten Secrets to Baking the Best Gluten-Free Bread, from Gluten-Free on a Shoestring
All photos by Anne unless specified otherwise.

Previous post

Mad Quickies 6.19

Next post

Drabble Lab 8: Solstice

Anne S

Anne S

Anne Sauer is an atheist with an appetite for science, good food, and making connections between the two. She is currently pursuing her MBA in Sustainable Management at Presidio Graduate School in San Francisco. Her favorite foods are salted caramel ice cream and chicken tikka masala. You can find her on twitter @aynsavoy.

No Comment

Leave a reply