By: Morgan Rease

Xanthan gum is a very common, very versatile food additive and can be found in many products. You probably have at least one item containing xanthan gum in your fridge or pantry right now (go check, this article isn’t going anywhere). It might be in some of your favorite foods, like a salad dressing or some tasty baked goods. But WHAT is it?

Xanthan gum is a hydrocolloid (a water-binding carbohydrate) produced via fermentation of simple sugars by the bacterium Xanthamonas campestris. The sugars can be derived from a variety of sources, including, but not limited to, corn, sugar cane, whey, and molasses.^[1] The production process is laid out in the flowchart below, or you can watch this video from the folks at howstuffworks.com.

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The resulting biopolymer is wonderful for thickening water-based solutions or for creating gels. Xanthan gum is added to ice cream to prevent large ice-crystal formation (large ice crystals can make ice cream grainy). Xanthan gum is added to gluten-free baked goods to improve their texture by providing some elasticity and air trapping power normally provided by wheat gluten.^[2] It can also be found in non-food applications, like providing the thickness of non-drip paint and controlling fluid loss in oil drilling. Don’t let its functional versatility be the basis for negative opinion!

The reason behind xanthan gums incredible water binding ability is its physical structure. Xanthan gum is composed of a linear (β1-4) backbone of glucose (like cellulose) and has trisaccharide side chains on every other glucose subunit. This particular branching pattern is thought to be key to the formation of Xanthan gum’s fivefold helical structure.^[3] This results in thixotropic behavior which means the thickness (viscosity) can be changed over time if shaken or agitated.

Thixotrophic fluids are defined by their decrease in viscosity with applied stress (translates from science-ese to English as: becomes thinner when agitated, like when you hit a ketchup bottle to get the ketchup out).

Gif courtesy of minutebuzz.com

Another characteristic of xanthan ‘gels’ is that they are thermo-reversible (they get thinner when heat is applied, like gravy). I put gel in quotes because to truly form a gel, xanthan gum must be mixed with another polysaccharide, such as  a glucomannan (konjac) or a galactomannan (guar gum or locust bean gum).^[4] Lastly, the gelling ability of xanthan gum is increased in ionic solutions, especially calcium ions. If you really want a thick, solid gel from xanthan gum, make sure you’ve got some calcium ions in your fluid, which is why it works in dairy desserts so well.^[3]

The coolest thing about xanthan gum is the series of events that led to its discovery. Time for a brief history lesson! During the Great depression, about 750,000 farms were foreclosed on.^[5] US farmers were in great need of new markets for their crops to stay afloat. Recognizing the need for long-term research and development, the Agricultural Adjustment Act of 1938 established four regional research labs to help find new uses and new markets for agricultural commodities. The Northern Regional Research Laboratory (NRRL) in Peoria, Illinois was working on improving the conversion of cornstarch to sugar for sweeteners and alcohol production. Acid-hydrolysis of starch produced small quantities of a bitter compound: isomaltose. Bitter compounds have no place in sweeteners, and this particular compound also happened to be difficult to ferment into alcohol too. Enter Allene Rosalind Jeanes, a USDA Chemist who wanted to study isomaltose, but needed a reliable source of it for a standard. It was known that the bacterium Leuconostoc mesenteroides produced dextran, a slimy polysaccharide, which could be hydrolyzed to isomaltose.

The strain of Leuconostoc mesenteroides used by Dr. Jeanes was originally isolated from a bottle of locally made root beer that had become ‘ropy’. Inspired by Swedish research describing dextrans potential as a blood plasma replacer, the NRRL would use an isolate from the same strain of Leuconostoc mesenteroides to produce dextran for use as a blood plasma extender during the Korean War and consequently saved countless lives. Dr. Jeanes also realized that microbial polysaccharides like dextran worked similarly to plant gums, which were being imported for use in foods. Jeanes, her team, and Dr. Martin Cadmus of the Fermentation Division of the NRRL eventually determined that Xanthomonas campestris produced substantial amounts of high-quality gum from glucose fermentation. Another new market for corn farmers!

In the early 1960’s, commercial scale production of xanthan gum began with the Kelco Corporation (now CP Kelco).^[6] Then, in 1969, the FDA approved xanthan gum for use in food as a stabilizer and thickener.^[7]

Gif courtesy of buzzfeed.com

So is xanthan gum something only food scientists and big factories can use? No! Xanthan gum most certainly has a place in the home pantry. And you don’t need to be busting out some crazy, modernist cuisine, molecular-gastronomy, peanut butter and goose liver foams to use it (that would actually be pretty gross…maybe. Somebody do it and email me how it turned out). That said, I’m not going to lay out a ton of recipes for you here. This article is long enough already and I couldn’t discuss every possible aspect of xanthan gum in one blog post. If you want some ideas, check out these websites:

More info on Xanthan Gum

Recipes using xanthan: http://www.molecularrecipes.com/tag/xanthan/

Explanation of how to use xanthan: http://www.modernistcookingmadeeasy.com/info/modernist-ingredients/more/xanthan-gum

Stuff I didn’t cover: https://google.com

Fun Facts: For all you biochemists out there, X. campestris utilizes the Entner-Doudoroff pathway and the tricarboxylic acid cycle to convert the glucose into xanthan gum.^[7] Dextran is still used as a plasma extender today.
Sources:

1. Palaniraj, A. and V. Jayaraman, Production, recovery and applications of xanthan gum by Xanthomonas campestris. Journal of Food Engineering, 2011. 106(1): p. 1-12.
2. Oulton, R. Xanthan Gum. Thickeners [website] [cited 2015 August 23].
3. Group, T.F., Xanthan, in Food polysaccharides and Their Applications, G.O.P. Alistair M. Stephen, Peter A. Williams, Editor. 2006, CRC Press.
4. Tania M.B Bresolina, M.M., Marguerite Rinaudoa, Joana L.M.S Ganterb, Xanthan–galactomannan interactions as related to xanthan conformations. International journal of Biological Macromolecules, 1998. 23(4): p. 263-275.
5. Moore, S. U.S. Farmers During the Great Depression. 2011 [cited 2015 August 26th].
6. Finkenstadt, G.L.C.a.V.L. A HISTORY OF CARBOHYDRATE RESEARCH AT THE USDA LABORATORY IN PEORIA, ILLINOIS. BULLETIN FOR THE HISTORY OF CHEMISTRY, 2008. 33, 103-111.
7. Petri, D.F.S., Xanthan gum: A versatile biopolymer for biomedical and technological applications. Journal of Applied Polymer Science, 2015. 132(23).