Gelzan

 Gelzan

(formerly named Gelrite®)

Gelzan is known as a plant-based food additive because it is produced naturally in specific plants like water lilies [8].

• Gelzan (Gellan gum) is composed prolifically of naturally occurring polysaccharide chains uniquely combined with one another in repeating orders which typically enhance the tissue growth in microbiological culture media. Polysaccharide is naturally a long chain of elementary carbohydrates joined together by glycosidic bonds [4].
• The unique strain which results in the excessive production of Gelzan or Gellan Gel is the economic strains of specific bacteria Pseudomonas elodea. It is also titled as Sphingomonas elodea (a non-pathogenic bacteria). Some other strains of the genus Sphingomonas are equally involved in the sustainable production of gelzan [7].
• When compared with agar, Gelzan remains preferably a gelling agent or an economical alternative agar substitute that contains rarely or no endogenous contaminants. That’s why it is utilized in slight quantity to adequately maintain the same texture as compared to agar.
• Structurally, it is composed of two units of d-glucose, one unit of d-glucoronic acid, and one unit of L-rhamnose. Its molecular structure maintains a molar ratio of 1:2:1 [5].
• Gellan Gums are also marketed on the distinctive names of various registered labels. For Example, Phytagel, Gelrite, Gel-Gro, Applied Gel, and Gelzan [6].
• There are respectively two distinguished types of Gellan Gums (GG) that are correctly classified on the comparative basis of the number of acyl groups present. They are extensively used for commercial purposes:
• Acylated Gellan Gums
• De-Acylated Gellan Gums [3].

PROCEDURE:

The working procedure of Sphingomonas paucimobilis which results in the effective production of Gelzan or Gellan Gum under suitable conditions is described below:

• Two key steps are typically involved in getting the pure culture of Sphingomonas paucimobilis which is necessary for the successful production of Gelzan or GG.
• A microbiological culture used to promptly initiate the fermentation process is allowed sufficiently to grow under suitable conditions in the high nutrient medium. This specific medium is rich in other nutrients like carbon or nitrogen sources which undoubtedly enhances the number of bacteria in starter culture and it also leads to the standard formation of EPS.
• This increase in bacterial population leads to the sustainable production of thicker concentrations in the high nutrient medium which will be used appropriately in the inoculation for further growth of desired bacterial population. This ideal medium is made by mixing water, marmite, organic honey, and skimmed milk (in dried form) in an adequate amount.
• After the propagation of beneficial bacteria Sphingomonas paucimobilis in a high nutrient medium, it is promptly transferred to a low nutrient medium. This preferred medium is made by mixing some ingredients like table salt, ammonia, etc. along with skimmed milk, organic honey, marmite in appropriate quantities. Both high and low nutrient mediums are properly sterilized using an autoclave to cautiously avoid possible contamination.
• This specific culture is further allowed to reasonably achieve saturation after cooling at room temperature. This saturation is accomplished by incubating the paucimobilis for 2 days in an insulated enclosure with suitable environmental conditions. The standard temperature of the enclosure is obstinately maintained at 30 degrees Celsius, and it is essential to shake the bacterial culture after regular time intervals until gellan gum is produced.
• A highly sticky and gelatinous culture is adequately prepared after 8 days which is then mixed with necessary Epsom salt to undoubtedly increase the concentration of magnesium atoms in the bacterial culture so that it helps in strengthening gel’s desired texture.
• After gently heating the specific culture in a microwave cautiously (avoiding over-boiling), sterile medium is achieved which is then poured into petri dishes and required number of plates are made by this sterile medium. That’s how gellan gum is obtained from bacteria [9].
• Commercially large sized fermenters are used for converting carbohydrates into gellan gel in the presence of particular bacteria. This gellan gum (Gelzan) is then treated in various ways to get its different forms that are described below:

1. 1. Acylated unclarified gellan gum
   2. Acylated clarified gellan gum
   3. Deacylated unclarified gellan gum
   4. Deacylated clarified gellan gum [4].

Figure 1: Flowchart showing production of various Gellan Gums

• Gelzan is available in different sizes and plastic containers of 100g, 200g, 250g, 1kg, and 5kg [1].

APPLICATIONS:

• Gellan Gums are knowingly used in an infinite variety of products belonging to different industries like the food industry, bakery, medical, pharmaceutical, confectionery, dairy, and beverages industries.
• Gellan Gums are used in typically making gel desserts because of their heat stability, gel strength, and transparency. In order to achieve excellent clarity in the texture of the gel, low acyl gellan gums are used. It imparts a good taste in desserts. It is not utilized solely, sometimes gets mixed with other gelling agents to maintain flexible and elastic texture.
• In bakery applications, it is widely consumed as a stabilizer in making bakery fillings, icing, frosting, glazing, and bakery mixes [2].
• Gellan gums appropriately give a refreshing feel in delicious juices in comparison with other stabilizers.it is used in assorted varieties of preferred beverages.
• It is used in making medicine, allergy relief, and bone repairing drugs [8].

SPECIFICATIONS:

Safe:  Gellan gel is considered safe and is widely consumed in the number of countries like the United States of America, China, Japan, Korea, Europe, and Canada. It is also approved by World Health Organization and used extensively by millions of people around the globe. No side effects are observed in humans [8].

TERMS & DEFINITIONS:

Pseudomonas elodea is economically capable bacteria (non-pathogenic in nature) that produces Gelzan during fermentation in the presence of adequate oxygen.

EPS correctly represents Extra Cellular Polysaccharides which are the base for the efficient production of Gelzan [3].

References:

1. BioTrend CliniSciences – Gelling agents for plant culture
2. Food Additives – What is High & Low Acyl Gellan Gum (E418) in food? Uses and Safety
3. Plant Cell Technology – Agar vs Gellan Gum – Which to Choose?
4. Science Direct – Gellan
5. Chemical Book – GELLAN GUM
6. Science Direct – “gellan is a linear, anionic, tetrasaccharide with average molecular weight of about 500 kDa [13], consisted of repeating carbohydrate units (1,3-β-d-glucose, 1,4-β-d-glucuronic acid, 1,4-β-d-glucose, 1,4-α-l-rhamnose)”
7. Science Direct – Elodea
8. HealthLine – What is gellan gum?
9. NCBI NIH – Bacterial Production of Gellan Gum as a Do-It-Yourself Alternative to Agar
10. Cinogel – A Good Overview Of Scientific, Technical And Commercial Aspects For Gellan Gum