A hydrocolloid with outstanding properties
Xanthan gum is a natural polysaccharide. It was discovered in the late fifties in the research laboratories of the US Department of Agriculture during research work into the industrial applications of microbial biopolymers. Extensive research revealed that the bacterium Xanthomonas campestris, found on cabbage plants, produces a high molecular weight polysaccharide, which protects the bacterium from heat or other microorganisms. This polysaccharide, called xanthan gum, proved to have technically and economically outstanding properties. The industrial importance of xanthan gum is based upon its exceptional qualities as a rheology control agent in aqueous systems and as a stabiliser for emulsions, suspensions and foams.
Top view of a xanthan gum molecule (Moorhouse et al. 1977)
Properties
Xanthan gum is a white to cream-coloured free flowing powder with a neutral taste. It is soluble in both cold and hot water and provides a rapid increase of viscosity. Even at low concentrations, xanthan gum solutions offer a higher degree of viscosity than other polysaccharides. Due to its elastic properties xanthan gum also features great stabilising effects, which allows the suspension of solid particles. Xanthan gum solutions are highly pseudoplastic (shear thinning) but not thixotropic, which means that after high shearing the initial viscosity is rebuilt instantaneously. Shear thinning enhances sensory qualities (flavour release, mouthfeel) and guarantees good pouring, brushing and cling of final products. Furthermore, it eases processing procedures such as mixing, pumping and spraying. Xanthan gum is very resistant to pH-variations and is therefore stable in both alkaline and acidic conditions. The thermal stability of xanthan gum is usually superior to most other water-soluble hydrocolloids. Its viscosity recovers after heat treatment steps during food processing, such as sterilisation or pasteurisation. Thus the rheological properties of the final products remain stable, irrespective of being kept in a refrigerator, stored at room temperature, or heated. Xanthan gum also improves the freeze/thaw stability of frozen foods.
Compatibility
Xanthan gum is compatible with most food, cosmetic and pharmaceutical ingredients. It tolerates most salts and specifically high levels of monovalent ions. Depending on the type of ions, pH and concentration, the addition of electrolytes can actually increase the viscosity and stability.
Xanthan gum also has an excellent stability in the presence of acids and can be dissolved directly into many acidic solutions. Furthermore, it is compatible with most commercially available thickeners.
Combinations of xanthan gum with galactomannans, such as guar gum, locust bean gum and tara gum show strong synergistic interactions. This means an increase of the viscosity, which is higher than the sum of viscosities of either gum alone. Solutions of xanthan gum and locust bean gum can form thermally reversible gels.
Xanthan gum is highly resistant to enzymatic degradation due to the nature of the sugar linkages and the structure of the side chains on the polysaccharide backbone. Pure xanthan gum can therefore be safely used in the presence of most common enzymes such as galactomannanases, cellulases, amylases, pectinases and proteases. Xanthan gum is not directly soluble in most organic solvents. However, up to 50% of common solvents can be added to aqueous solutions of xanthan gum without precipitation of the gum.
Preparation of Solutions
Xanthan gum is a hydrophilic biopolymer readily soluble in cold and hot water. Rapid dissolution requires an even dispersion of xanthan gum particles in the aqueous medium. For that reason, intense agitation of the solution is necessary when introducing xanthan gum into the aqueous phase. Insufficient dispersion will cause lumps. Preblending
xanthan gum with other dry ingredients orpresuspending it in oil or alcohol facilitates the
preparation of xanthan gum solutions.
Applications
Due to its extraordinary properties as stabiliser and thickener xanthan gum is extensively
used in the food, personal care and pharmaceutical industry. In addition, xanthan gum is applied in various industrial applications and for oil drilling. In all of these areas xanthan gum is recognised as an excellent stabiliser and useful processing aid.
| Food Applications | Usage % | Function |
| Salad Dressings | 0.1 – 0.5 | provides easy pourability and good cling; suspends spices |
| Bakery Products, Gluten Free Bakery Egg-free Products | 0.05 – 0.3 | binds water; improves texture and moisture retention; suspends fruits and nuts |
| Beverages | 0.05 – 0.2 | enhances mouthfeel; suspends fruit pulp |
| Instant Products | 0.05 – 0.2 | contributes body; quick viscosity build up in cold and hot water |
| Prepared Food | 0.1 – 0.3 | stabilises; avoids syneresis |
| Soups, Sauces and Gravies | 0.05 – 0.5 | provides good temperature stability; prevents separation; improves texture |
| Frozen Food | 0.05 – 0.2 | provides good freeze/thaw stability; contributes smooth texture |
| Dairy Products and Plant-based Alternatives | up to 0.30 | inhibits syneresis; stabilises emulsions |
| Toppings | 0.05 – 0.3 | stabilises foams and emulsions; provides good flow and cling |
| Meat Products and Plant-based Alternatives | up to 1.2 | binds water; inhibits syneresis |
| Low-calorie Products | 0.1 – 0.5 | improves texture; stabilises |
| Personal Care Applications | Usage % | Function |
| Creams and Lotions | 0.2 – 1.0 | stabilises emulsions; gives creamy consistency |
| Shampoo | 0.2 – 0.5 | controls rheology; suspends insolubles |
| Hair Gel | 3 – 5 | good fixation properties and curl retention performance |
| Oral Care Applications | Usage % | Function |
| Toothpaste | 0.5 – 1.0 | provides easy pumpability and excellent flow properties; gives good stand on the brush |
| Tooth Tabs | 1.50 | provides pleasant mouthfeel and good foaming |
| Industrial Applications | Usage % | Function |
| Agricultural Chemicals | 0.1 – 0.3 | suspends active ingredients; controls drift and cling |
| Cleaners | 0.2 – 0.7 | provides good pH-stability; extends contact time |
| Polishes | 0.2 – 0.7 | suspends abrasive components |
| Water Based Paints | 0.1 – 0.3 | controls rheology; stabilises pigments; inhibits drip off |
| Textile and Carpet Printing | 0.2 – 0.5 | improves processing; controls colour migration |
| Adhesives | 0.1 – 0.3 | controls rheology and penetration |
| Paper Industry | 0.1 – 0.2 | acts as suspension aid and rheology control |
| Ceramic Glazes | 0.3 – 0.5 | suspends solids effectively |
| Oil Drilling | 0.1 – 0.4 | controls rheology; provides good stability against salt, temperature and shear |
| Enhanced Oil Recovery | 0.05 – 0.2 | functions as mobility control agent |
| Animal Feed | Usage % | Function |
| Liquid Milk Replacers | 0.05 – 0.2 | stabilises water insoluble ingredients |
| Pet Food | 0.1 – 0.4 | prevents syneresis; contributes body to gravy |
| Pharmaceuticals | Usage % | Function |
| Suspensions and Emulsions | 0.1 – 0.5 | provides excellent stability and good flow |
| Tablets | 1.0 – 3.0 | retards drug release |
| Lozenges | 0.3 – 1.0 | prolongs contact time of active ingredients |
Storage and Stability
In its powder form xanthan gum can be easily andsafely stored for several years. Xanthan gum solutions, however, although more resistant to microbial attack than most other water soluble biopolymers, should be protected by adequate preservatives when the storage time exceeds 24 hours.