Xanthan Gum Description
Xanthan gum is a polysaccharide produced by the fermentation of the bacterium Xanthomonas campestris. This organism is found in nature on the leaf surfaces of green vegetables, particularly the brassica family.
Indeed it is used as a rheology control agent in aqueous systems and as a stabilizer for emulsions and suspensions. Its numerous areas of applications cover a broad spectrum and range from the food industry to oil recovery.
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Xanthan gum is a white to cream-coloured free flowing powder soluble both in hot and cold water, but insoluble in most organic solvents. Its industrial importance is based upon its ability to control the rheology of water-based systems. Even at low concentrations xanthan gum solutions show a high degree of viscosity in comparison with other polysaccharide solutions. This property makes it a very effective thickener and stabiliser.
The chemical structure of the xanthan gum molecule in aqueous solution confers three unique properties:
- excellent flow control, even at very low concentrations
- long lasting suspension of particulates, even in complex formulations
- ability to withstand severe shear, heat treatment, enzymic attack and high salt levels
The ability of xanthan gum to perform as a long-lasting, highly effective stabiliser which holds particulates in solution is valuable to manufacturers who want to offer long shelf-life products with no risk of separation and sedimentation.
Xanthan gum solutions are highly pseudoplastic but not thixotropic, i.e. even after high shear rates the initial viscosity is rebuilt instantaneously. Xanthan gum is more pseudoplastic than most other hydrocolloids. This pseudoplasticity enhances sensory qualities (flavour release, mouth feel) in final products and guarantees high-degree mix-, pump- and pourability. Xanthan gum solutions are very resistant to pH-variations, i.e. they are stable in both alkaline and acidic conditions. The thermal stability of xanthan gum is usually superior to most other water-soluble polysaccharides. The viscosity of xanthan gum solutions is completely recovered after heat treatment steps during food processing e.g. sterilisation. The rheological properties of the final products thus 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.
Xanthan gum is tasteless and does not affect the taste of other food ingredients.
The caloric value of xanthan gum is very low e.g. of 0.6 kcal/g.
Curiosity: the word xanthan is derived from the Greek meaning a yellow colouration. When the fermentation stage of the production of xanthan gum is complete, the crude gum is indeed a bright yellow!
Extensive investigations with respect to toxicology and safety have shown that xanthan gum is a safe food additive. It was cleared by the FDA (the US Food and Drug Administration) in 1969 and registered in the Code of federal Regulations.
In 1980 xanthan gum was approved as a food additive in the European Community under the number E 415. In 1988 the ADI (acceptable daily intake) of xanthan gum was changed to “not specified” confirming its status as a safe food additive. The xanthan gum food grade produced by Biopolymer members fully meets the standards and the purity criteria issued in different regions of the world or internationally, such as the Food Chemicals Codex and JECFA, the US Pharmacopoeia/National Formulary, the European Directives and the European Pharmacopoeia.
Due to the extraordinary properties as stabiliser and thickener xanthan gum is widely used in the food, cosmetic and pharmaceutical industry. Xanthan gum is also used in various industrial applications as well as for oil drilling. In all these areas xanthan gum is accepted as an excellent stabiliser and a useful processing aid.
In pourable salad dessings xanthan gum has proven to be an ideal stabiliser. The three-dimensional network formed by the xanthan gum molecules prevents oiling off and separation of insoluble solid particles. Further, the shear-thinning flow behavior contributes to mixability, pumpability and pourability of industrially produced dressings. The rheological properties of xanthan gum together with its high tolerance towards acids and salts guarantee a long shelf life for these oil-in-water emulsions.
In the bakery industry xanthan gum is used to increase water binding during baking and storage and extends the shelf life of baked goods and refrigerated doughs. In soft baked goods xanthan gum can also be used as an egg replacement, in particular the egg-white content can be reduced without affecting appearance and taste. Small amounts of xanthan gum give higher baking volume in cakes. Solid particles like raisins and nuts are prevented from settling during baking. Gluten-free bread can be baked with xanthan gum while still providing a fine-pored structure and elastic surface.
In beverages xanthan gum effectively suspends insoluble particles for long periods of time. Xanthan gum imparts enhanced mouthfeel with full-bodied taste and good flavor release. For the stabilisation of fruit pulp it is recommended to use xanthan gum in combination with other hydrocolloids e.g. CMC. Because of its solubility in both hot and cold media and its excellent stabilising performance, xanthan gum can be used in almost every instant product, e.g. soups and sauces, desserts, instant drinks and toppings.
Many of today’s prepared foods, semi-prepared food and convenience foods take advantage of the stabilising properties of xanthan gum. In order to obtain a specific flow behavior and texture xanthan gum if often used in combination with other hydrocolloids.
In soups, sauces and gravies xanthan gum provides a uniform viscosity over a wide temperature range. When the sauces are added to spaghetti, potato-chips etc. the presence of xanthan gum imparts good cling and prevents separation of the sauce.
In frozen foods xanthan gum imparts excellent stability and water retention during several freeze/thaw-cycles and reduces the uncontrolled formation of ice-crystals. In combination with other hydrocolloids xanthan gum gives a smooth texture and improved shelf life.
The dairy industry uses xanthan gum in a variety of applications. Xanthan gum is often used in combination with carrageenan or other hydrocolloids to stabilise milk shakes, yoghurts and dairy desserts. The pseudoplastic properties of xanthan gum facilitate the production of cheese spreads, and together with galactomannans it is used in cream dressings for cottage cheese to avoid syneresis.
Xanthan gum provides emulsion stability and water retention to different kind of toppings and ensures both an excellent flow and a good cling.
The meat industry uses xanthan gum in preparation of pate and sauces. In countries where direct treatment of meat products is permitted, it is used in blends of stabilisers for sausages and brine solutions for ham injection.
Xanthan gum is widely used in low-calorie products to bind water and to improve texture and mouthfeel without adding caloric value.
In liquid milk-replacers for calves and piglets xanthan gum is used to stabilise the suspension of insoluble substances.
Xanthan gum is often used in combination with locust bean gum and guar gum as stabiliser and binder in the formulation of canned gravy-based pet food.
Xanthan gum is an ideal stabiliser for various types of tooth pastes, e.g. gels or pumpable types. It provides uniformity and stability to the tooth paste, makes it easy to be pumped or squeezed and gives a consistent and smooth string. Xanthan gum can be used as an emulsions stabiliser and water-binder in creams and lotions. It imparts high viscosity at low concentrations and enables pastes and creams to hold their shape. In shampoos xanthan gum is used to adjust the viscosity and flow properties and it suspends insolubles such as pigments or other active ingredients in medicated shampoos.
Xanthan gum is an excellent stabiliser for pharmaceutical formulations. It uniformly suspends water-insoluble ingredients, e.g. barium sulphate in X-ray contrast media and perfectly stabilises all kinds of pharmaceutical emulsions. In lozenges xanthan gum prolongs the contact time of the active ingredient, in tablets xanthan gum can be used to create a retarded drug release effect.
Other industrial applications:
The agrochemical industry uses xanthan gum as stabiliser in flowables. Xanthan gum has good suspending properties, controls the size of droplets and prevents drifting. It also imparts good cling thus increasing the contact time between the active ingredient and the crop.
As a thickening agent with high pH stability xanthan gum is able to thicken acid and alkaline cleaners, e.g. toilet cleaners. Its pseudo-plasticity increases the cling to vertical surfaces and extends contact time.
Xanthan gum is also useful for suspending abrasive components in metal polishes and to stabilise polish emulsion.
In water based paints xanthan gum is used to stabilise the pigments and to control the flow properties of the paint.
In textile and carpet printing pastes xanthan gum is used to control fine-line and colour migration. Its temperature stability and pseudo-plastic properties improve space printing and dyeing processes.
The viscosity of water based adhesives can easily be adjusted by small amounts of xanthan gum. Its rheological properties facilitate handling during application. In the paper industry xanthan gum can be used as suspension aid and for rheology control.
Xanthan gum can be used in water based printing inks to provide the proper viscosity during application, to control penetration and to increase stability. Xanthan gum is an excellent suspending aid for ceramic glazes and many other hard-to-suspend mixtures.
The oil industry uses xanthan gum in oil well drilling fluids, well completion and fracturing fluids and as a mobility control agent in flooding operations for enhanced oil recovery.