A gelling agent produced through fermentation of an algae, gellan gum is used in molecular gastronomy to make all sorts of firm-jellied pieces with distinctive shapes.
Gellan gum is produced by fermentation. The micro-organism naturally responsible for this fermentation is the Sphingomonas elodea, which lives on an aquatic plant, Elodea Canadensis. It is native to North America and naturalized on most continents. The natural gum was discovered in the late 1970s and has since been produced by fermentation of calcium hydrates in Sphingomonas elodea monocultures extracted from natural sources. The gellan gum is then isolated from the culture bath by precipitation in an alcohol since it is not soluble in ethanol.
Gellan gum is a water-soluble gelling agent which presents very special characteristics. There are two types of gellan gum which are distinguished by their chemical composition. One has a high rate of acyl, the other a low rate of acyl. Acyl is derived from an acidic group of molecules. High-acyl gellan gum forms gels that are very flexible, elastic and that do not break. Low-acyl gellan gum, however, can create strong gels that are crumbly and non-elastic. Mixtures of these two types of gum in varying proportions can be developed to obtain the specific properties required for the many uses of gellan gum.
In an aqueous preparation, gellan gum can form a solid gel at a concentration as low as 0.1%. The temperatures for dissolving and gelling of gellan gum vary according to the types used. Dissolution occurs between 85°C (185°F) and 95°C (203°F) and gelling takes place on cooling between 10°C (50°F) and 80°C (176°F). Gellan gum gels are not thermo-reversible, that is to say, the gels formed are not altered by high heat. Once set, the high-rate acyl jelly can be heated up to about 80°C (176°F) without melting, whereas the low-rate acyl gel is able to withstand much higher levels of heat. These gels retain their stability under a wide range of pH.
Gellan gum is used mainly in the food industry as an anti-settling agent, thickener, stabilizer or to structure prepared foods. Used in very small doses, it acts as an anti-settling agent in liquids, while adding only a very light viscosity. It may well allow, for example, the uniform distribution of cocoa in chocolate milks or strengthening agents like calcium or fiber in all kinds of beverages.
It does not alter the taste of foods to which it is added. Gellan gum’s resistance to heat allows processed foods to better support temperature changes during transportation and storage. The processed foods most likely to contain gellan gum are: baked goods, cake icings, various sweets, jellies and spreads, jams, puddings, sauces, and many dairy products or foods ready for the microwave. Gellan gum is used as a substitute for starch in some prepared products. Finally, it offers good moisture retention. Thus, for example, pie fillings that contain gellan gum are less likely to wet the crust.
Gelatinous beverages are very popular in Southeast Asia and gellan gum can be used to make them. It was also used by the Clearly Canadian Beverage Corporation company, in the late 1990’s, for a briefly marketed drink in North America called Orbitz, which featured suspended colored flavor spheres in a clear liquid
Gellan gum can also be used in cosmetic and hygiene products such as makeup, facial masks, creams and lotions, for a good hold and a pleasant texture. It can also be used as an anti-settling agent and stabilizer in shampoos and conditioners. In sunscreens, gellan gum can be used to stabilize the oily phase and to distribute active agents uniformly.
In pharmaceuticals, for example, gellan gum is used to make tablets that are easy to swallow, as well as to adjust the rate of release of their medicinal compounds in the body. It is also used in biotechnology, as replacement for agar-agar, as a growth environment of bacteria. Indeed, gellan gum offers benefits in the cultivation of thermophilic microorganisms, that is to say, living at high temperatures. Finally, it is used in the manufacturing of indoor deodorizers to be used in warm environments such as cars.
Creative cooking applications
As a gelling agent, gellan gum can be used to achieve a variety of jellies and a multitude of dishes requiring jelly, such as terrines or aspics. To activate its properties, the gellan gum powder needs only to be dispersed in a liquid of choice, heated and stirred until dissolved. The gelling will occur during cooling and it may be necessary to place the preparation in the refrigerator. Gellan gum gels are easily sculpted so it is often used to make all sorts of original dishes from a full range of liquid foods such as broths, infusions and juices.