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ADD:Fengqiao Town Fengbei Industrial Area, Zhuji, Zhejiang , China
CONTACT PERSON: Mr. Wang
M.T.:0086-13806769695
TEL:0086-575-87040258
FAX:0086-575-87040068
E-MAIL:Tech-way@163.com
P.C.:311811 |
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The Source of Gellan Gum
Gellan gum is a bacterial exopolysaccharide, prepared commercially by aerobic submerged fermentation from Sphingomonas elodea (previously called Pseudomonas elodea), in a manner similar to xanthan. discovered in 1978,1988 Approved in Japan,1992 USA full approved.
Compared with other colloids, Gellan Gum has many peculiar advantages:
1. Low dosage;
2. Excellent thermal and acid stability;
3. Good taste-releasing ability;
4. High transparency;
5. Adjustable gel elasticity and rigidity;
6. Good combinability. |
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The Characteristic Of Gellan Gum
| Characteristic |
Advantage |
| 1. Very Low dosage, form gel at 0.05-0.25% concentration |
Gellan gum is a very effective gelling agent |
| 2. Excellent thermal stability and acid stability |
1.Little effect to gel strength after heat sterilization.
2.Its powder form allows longer term of use and long-term stability even under acid condition. |
| 3.Sodium or potassium irons can form thermal reversible gel, while Magnesium or calcium irons form thermal un-reversible gels |
Can be made into thermal reversible and thermal un-reversible gels |
| 4．Good combination with other hydrocolloids |
Adjustable gel elasticity and rigidity |
| 5．Good compatibility with other ingredients |
Can be widely used in many formulations |
| 6．Can form gel between pH 3.5~7.0 |
Can form high quality gels and have good gel strength in acid to neutral food formulations. |
| 7.Anti-aging function |
Prevent aging and viscosity raising of starch |
| 8.Not easy lead to enzymolysis |
Enabling flexibility in the manufacturing process, very suitable for Microbiological media and plant media. |
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The Structure of Gellan Gum
The monosaccharide building units of gellan gum are glucose, glucuronic acid and rhamnose in the molar ratios of 2:1:1. The primary structure, a tetrasaccharide repeating unit is shown in Fig.1. In the native form of the polysaccharide, there are approximately one and a half O-acyl groups per repeating unit. Originally the O-acyl substituent was thought to be O-acetyl, resulting in the various forms of gellan gum being referred to as high-and low-acetyl, and so on. Recent studies by Kuo et al. suggest that gellan gum contains both O-acetyl and O-L-glyceryl substituents on the 3-linked glucose unit, the former tentatively assigned to the 6-position and the latter to the 2-position. Analysis of samples in our laboratory following this work has indicated that glycerate substitution predominates over acetate. Undoubtedly, these bulky glycerate groups hinder chain association and account for the significant changes in gel texture that accompany deacylation. Inclusion of bulkier substituents on the gellan gum backbone has an even more dramatic impact on properties. For example, welan gum and rhamsan gum, which have the same backbone as gellan gum but are substituted by mono- and disaccharide side-chains, respectively, have no similarity to gellan gum in solution behavior.
The shape or conformation adopted by the gellan gum molecule as a result of this primary structure has been under investigation for a number of years using X-ray crystallography. The quality of early diffraction patterns was not adequate to permit a detailed structural Analysis. Subsequent work at Bristol, although resulting in high-quality diffraction patterns from well-oriented polycrystalline samples, also failed to produce a structure consistent with the X-ray data. A recent re-examination of the Bristol data has indicated that gellan gum forms an extended intertwined, three-fold, left-handed parallel double helix. Molecular shape in the solid state is usually an indicator of molecules associate in solution. The mechanism whereby gellan gum molecules associate in solution is believed to involve ion-mediated aggregation of double helices.
Fig.1. Low Acyl Gellan gum tetrasaccharide repeat unit
Fig. 2. High Acyl Gellan gum tetrasaccharide repeat unit
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The Production of Gellan Gum
Over the past 20 years, bacteria have become an increasingly important source of polysaccharides. Dextran, a blood plasma extender and a key constituent of certain types of chromatographic materials, and xanthan gum, the most extensively tested and one of the most intensively researched food polysaccharides, are good examples of bacterial polysaccharides. Kelco Division of Merck & Co.Inc. has pioneered the development of bacterial polysaccharides and has now isolated in excess of 900 gum-forming bacteria. Although all of the gums produced by these bacteria are of scientific interest, most are not of commercial value because they do not offer significant advantages over existing alternatives. However, there are a few notable exceptions, namely rhamsan gum (S-194), a more efficient suspending agent than xanthan gum; Biozan welan gum ( S-130), a thickener for oil-field applications with superior thermal stability to xanthan gum and gellan gum ( S-60), a novel gelling polysaccharide.
Gellan gum offers a potential solution to many of the problems that exist with current gelling agents. Being a fermentation product, it can be produced on demand and with consistent quality. Availability and variability are, thus, not concerns. It is functional at very low use levels and is therefore, very efficient in many applications. Gellan gum can provide a range of gel textures as opposed to a single characteristic texture. Consequently, it can be used to mimic the texture of existing gelling agents or to create new textures. In today’s food industry, a tool to create new textures and hence permit the creation of new , differentiated food products would be highly desirable. Gellan gum is not a difficult product to use and although it is anticipated that eventually various form for a particular application will be determined by textural rather than by complex functional considerations. It should be stressed that gellan gum is in its early development stage, and much still has to be learned about its basic chemistry, properties, applications and , indeed, its ultimate utility in the market place. In this respect, it is encouraging that, for the first time in the history of hydrocolloids, commercial development is proceeding in parallel with the generation of fundamental scientific data on the product. Gellan gum is produced by the bacterium Pseudomonas elodea. The gum is formed by inoculating a carefully formulated fermentation medium with this organism. The medium consists of a carbon source such as glucose, a nitrogen source and a number of inorganic salts. The fermentation is allowed to proceed under sterile conditions with strict control of aeration, agitation, temperature and pH. When fermentation is complete, the viscous broth is pasteurized to kill the viable cells and then subsequently processed to recover the polysaccharide in either the fully acylated native form or the deacylated form, as show in Fig.2. Gelrite-gellan gum for microbiological media and related applications and Kelcogel food grade gellan gum ---are low acyl products. Gels from the native material can loosely be described as cohesive and elastic, while those from the deacylated materials are strong and brittle. Materials of intermediate acyl content, which can be obtained by careful control of the deacylation step, provide gel textures intermediate between those of the native and fully deacylated products.
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The Specification of Gellan Gum
Low Acyl Gellan gum
| Specification items |
Units |
Limits |
| Gel Strength |
g/cm2 |
≥800 |
| Transparency |
% |
≥74 |
| 80Mesh Fine Powder |
% |
≥98 |
| Loss on drying |
% |
≤12.0 |
| Ash |
% |
≤15.0 |
| PH 1% Solution |
|
4-7 |
| Arsenic |
ppm |
≤2.0 |
| Lead |
ppm |
≤2.0 |
| Bacterium account |
cfu/g |
≤10000 |
| Yeast & Mould |
cfu/g |
≤300 |
| E. Coli |
MPN/100g |
Negative |
| Salmonella |
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Negative |
Packing: 25kg/drum.
Store: Preserve in well-closed containers, and store at room temperature.
Expiry date: one year. |
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