Xanthan gum is a natural thickening and stabilising agent used to create full flavoured and perfectly smooth fluid gels, purées, and emulsions. It improves or modifies textural qualities, pouring characteristics and cling. The added viscosity that it imparts adds a sensation of enhanced body and mouth feel without reducing flavour impact.
Xanthan gum can also be used as a substitute for traditional thickening agents like gelatine, gluten and starch, where it has been shown to provide better flavour release and a more pleasing texture or mouth feel.
Xanthan gum does not solidify like gelatine, but can become highly viscose or thick when allowed to set. When vigorously agitated the formula will become liquid again. This is known as pseudo-plasticity and is a key feature of Xanthan gum.
Xanthan Gum in Production
Xanthan gum is derived from a fermentation process by a micro-organism known as Xanthomonas Campestri. The fermentation process transforms sugars, nitrogen, magnesium and other minerals into polysaccharides. Polysaccharides, like Xanthan gum, are characterised by large molecules and in some cases are water soluable, Xanthan gum is highly water soluable, which results in thick solutions from very small quantities. Xanthomonas Campestri occurs naturally on plants from the cabbage family and it is often responsible for the presence of dark spots on broccoli, cauliflower and other leafy vegetables.
In production, Xanthomonas Campestri are inoculated in a sterile growth medium until the fermentation process is complete. Post fermentation, the micro-organisms are eliminated through a heat sterilisation process. The Xanthan gum is collected through precipitation, centrifuging and drying, it is then ground into a powder. Xanthan is mostly used in the food industry. However, it is also used in cosmetics, personal hygiene products, and the pharmaceutical industry, where it is mostly used as a stabilizer.
Specification, Limitations and Culinary Uses
Heat
Xanthan gum solutions are unique in their ability to tolerate a wide range of temperatures and will retain their viscosity until a definite "melting temperature" is reached. Melting temperatures are dependent on the strength of the Xanthan gum solution created. However, a strong Xanthan gum solution can maintain its viscosity up to 100°C and above. When the solution has cooled to below the melting temperature it will regain its viscosity once more. Determining the melting temperature of a specific Xanthan gum solution is a matter of experimentation.
This feature allows the chefs to create Xanthan solutions with predictable viscosities at various temperatures. As a result, Xanthan is great for creating perfectly smooth fluid gels and purée, thick and unctuous sauces and unique gelatinous textures.
Tip:Try adding Xanthan gum to a Pumpkin or Celeriac purée for an ultra-smooth result.
Acidity pH
Xanthan gum is virtually un affected by pH and uniform and high viscosity is maintained over the pH range 2-12. However, differences in viscosity with pH are more evident at low concentrations of Xanthan gum.
Salts
Salts have varied effects on the viscosity of a Xanthan solution, but essentially the they are minor and dependent on the concentration of the solution. Extremely low concentrations can experience minor decreases in viscosity, while medium-high strength concentrations actually notice minor increases in viscosity. Mostly this will not have a noticeable effect on your Xanthan creations, but if you find that you are not getting the desired result you might consider this as the cause and adjust your formula to compensate.
Alcohol
Xanthan gum tolerates alcohol up to 60% volume.
Stabilising Effects
One of the benefits of having a tolerance to heat and pH means that the addition of Xanthan gum can help to stabilise sauces that have a tendency to split. Consider sauces like Beurre blanc, Hollandaise, Béarnaise, and Sabayon, which are all emulsions. Typically to avoid sauces like these from splitting and create the desired consistency chefs will add more or less eggs or butter or both (depending on the sauce). Traditionally, this would mean finding a compromise between flavour and texture. Eggs and butter will thicken the sauce while reducing the impact of the flavour base, adversely the liquid flavour base will thin the sauce and increase the chances of splitting. The addition of Xanthan gum will allow you to stabilise your sauce and even increase the ratio of flavour base to butter/eggs.
Xanthan gum is also freeze/thaw tolerant, which means you can freeze sauces that would traditionally split after freezing.
In gluten-free baking, Xanthan adds “stickiness” to reinforces gluten-free flour mixtures. However, it worth mentioning that excessive Xanthan gum will create an undesirable "clumpy" texture.
Tip: Clumping can be overcome through the addition of Guar gum obtained from Guar beans.
Pseudo-Plasticity
As mentioned Xanthan gum has a pseudo-plastic character, which means that when it is allowed to rest it will thicken and when it is agitated or shaken-up it will thin. The advantage of this, given the advantages mentioned above, means that it is perfect for creating coating sauces like salad dressings. Tolerance to pH allows for thick and creamy acid-based emulsions (like salad dressing) and Pseudo-Plasticity allows sauces to be applied to salad leaves and other produce in thin layers, which then sets giving the desired coating effect.
Hot sauces like the Beurre blanc mentioned above can also take advantage of pseudo-plasticity with the use of a stick blender to agitate the sauce before application.
Xanthan Gum Preparation, Tips and Tricks
Xanthan gum belongs to the hydrocolloid family, and as such, its molecules must have time to hydrate after having been dissolved in liquid. This hydration period allows water to penetrate inside hydrocolloid molecules, which then facilitate reactions as they are surrounded by water and suspended in the solvent. Hydration can be done equally well in a hot or cold liquid.
As mentioned Xanthan gum is a robust food additive and will withstand salt, high pH and even alcohol up to 60%, but when possible, it is best to complete the hydration phase before these additions.
Xanthan hydrates quickly at all temperatures, so it has a strong tendency to clump. One popular dispersion method is to disperse in oil (either on a 1:1 or 1:2 ratio of xanthan to oil) followed by vigorously whisking and, optionally, straining to remove any remaining clumps. Another method is to thoroughly mix xanthan with a small amount of sugar, preferably in a mortar, prior to dispersion. This delays the hydration enough to allow the gum to disperse before it has a chance to form lumps. As when working with other hydrocolloids, vigorous whisking or mixing with a hand blender works very well to aid dispersion.
The History of Xanthan Gum
Xanthan gum was discovered in the late 1950s after an extensive research effort by Allene Rosalind Jeanes and her team at the US Department of Agriculture.
In 1964, CP Kelco pioneered the production of polysaccharide gums by viscous fermentation and subsequently, commercialized Xanthan gum. Since then, Xanthan has been used in thousands of applications by a multitude of industries. After extensive toxicological testing that verified its safety, Xanthan was approved in the United States for general use in foods in 1969.
References:
KELTROL®/KELZAN® Xanthan gum Book 8th Edition
Molecular Gastronomy by Molecule-R
On Food and Cooking By Harold McGee
