Xanthan Gum...Say What?

Xanthan gum was something I first noticed when I took a few tentative steps into gluten free cooking.  Planning to make a cake as a hostess gift, I bought it in a giant bag guaranteed to last approximately forever, and didn't ask any questions.  I was after a decent tasting cake, not a science lesson.  But during my Food Science class last semester, I started wondering what it was and why it was used so much in gluten free baking.

Scientifically, xanthan gum is a polysaccharide, or a bunch of individual sugar molecules linked together in a chain.[1],[2]  The individual sugars are D-glucose, D-mannose, and D-glucuronic acids, for those biochemically inclined.[2]  It is produced by a bacterium that ferments carbohydrates, creating a gel that is then dried and milled.[1],[2],[3]  The specific carbohydrate fermented varies by the xanthan gum manufacturer.[4]  Thus, xanthan gum is a carbohydrate - one that contains quite a lot of fiber (7g per tablespoon according to Bob's Red Mill).[1]  Some people, apparently, don't digest xanthan gum well, reporting various symptoms from mild intestinal discomfort to severe pain.[3]   

It turns out that xanthan gum isn't something that is used exclusively in gluten free cooking.  In fact, it's used commercially as a thickener and/or stabilizer in salad dressings, sauces, refrigerated doughs, dry mixes, emulsions, ice creams, and cakes.[2]  For example, both Edy's Slow Churned Cookie Dough Ice Cream and Duncan Hines Classic Yellow Cake Mix - obviously not gluten free - contain it.[5],[6] 

In gluten free cooking, specifically, xanthan gum can help "replicate some of the stretching and structural characteristics of gluten."[3]  Gluten provides structure because it is elastic and plastic - it stretches in response to expanding heated gases and then is locked in place, holding that stretch, when heat coagulates the proteins.[2],[4]  Without gluten - or something to replace gluten's elasticity and plasticity - gluten-free products are heavy, dry, and/or crumble to pieces.[4]  As a result, the vast majority of gluten free baking recipes call for a binder (like xanthan gum) to improve elasticity and strengthen the baked goods' protein structure.[7] 

It doesn't take much - most recipes call for 1/4-2 teaspoons of xanthan gum per cup of flour.  In fact, an eighth of a teaspoon short or heavy can make a big difference in the final product, according to America's Test Kitchen's brand new The How Can it Be Gluten Free Cookbook. 

For more information about

Xantham Gum, see

[1] Bob's Red Mill on Xanthan Gum

[3] The Kitchn on Xanthan Gum

[4] Gluten Replacers in Gluten Free Baking

Other Sources

[2] Brown, Amy.  Understanding Food:  Principles of Preparation.  4th Ed.  Belmont, California:  Wadsworth, Cengage Learning, 2011.  Print.

[5] Edy's Slow Churned Cookie Dough Ice Cream

[6] Duncan Hines Classic Yellow Cake Mix

[7] The Editor's at America's Test Kitchen.  The How Can It Be Gluten Free Cookbook.  Brookline, Massachusetts, America's Test Kitchen, 2014.  Print.

This post is not intended to address the safety of consuming xanthan gum.  I did find an article by Chris Kressler here that attempts to grapple with that question, but I cannot vouch for its accuracy or completeness.