Guar gum

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Other names/abbreviations:

Guaran Gum cyamopsis

Material type:	Polymer
Material group:	Hetero polysaccharide, branched Galactomannans
Monomer(s):	D-galactose D-mannose
Links:	alpha-(1-4) alpha-(1-6)
Origin of the polymer:	Natural
CAS-Number:	9000-30-0
EINECS-Number:	232-536-8

Structure

(→4)-α-D-mannose(1→) (main chain) α-D-galactose(1→6) (side chain) [8]. Crystallographic data in [9].

Chemical properties

Behavior in solution
Hydrates rapidly in cold-water systems to give highly viscous colloidal thixotropic dispersion [8]. Complete hydration typically occurs in about 30 minutes, depending on preparation [8].

Maximum viscousity is achieved at 25-40 °C. Viscosity is not affected by pH in pH 1.0-10.5. This is believed to be because of the nonionic uncharged nature of the molecule. Hydration rate is however. Maximum hydration rate is at pH 8-9, while the slowest hydration rate is pH >10 and <4. since guar gum is nonionic, it is not sususceptible to salting out. the stability of guar gum solution is good with mono-,di-, and trivalent ions (both cations and anions), and the viscousity increases with increasing concentrations of salt. the viscosity decreases with inceasing concentrations of sugar. sugar protects guar gum from hydrolysis and loss of viscousity [1].

Guar is stable at pH 10-12. At pH 1-2, guar depolymerizes in a short period of time [8].

Biological properties

Gastrointestinal properties:
Retards gastric emptying when used as a dietary fiber. The fiber decrease postprandial insulin levels, indicating a slowing down of glucose absorption [2]. Guar gum stimulate the growth of colonic microflora [3].


Antiviral activity:

Inhibitor/Concentration (μg/mL)	200
Adsorption HSV-1 in Vero cells [5]	75
Adsorption HSV-2 in Vero cells [5]	90
Adsorption and replication HSV-1 in Vero cells [5]	75
Adsorption and replication HSV-2 in Vero cells [5]	85

Inhibition of virus multiplication in cells.

Cell line	Concentration
Vero cells [5]	200

Maximal non-cytotoxic concentration (μg/ml).


Molecular biology
10-35% inhibition on the restriction enzyme HindIII at 100-500 μg polysaccharide / μg λ DNA [6].


Misc.
Guar gum reduces the level of serum lipids. Hydrolyzed guar gum also reduces serum lipid levels, but not as well as the guar gum. Especially the less volatile lipids like palm oil [4].

Hepatic levels of cholesterol and tricaylglycerol were lowered, but not the levels of phospholipids [4].

Guar gum increase the rate of bile flow [4].

Guar gum feeding increases the activity of 3-hydroxy-3-methylglutaryl-CoA reductase and cholesterol 7a-hydroxylase irrespectively of the dietary fat source [4].

No enhancement of lectin hemagglutinability [4].

Physical properties

Appearance
	Physical state @ 20°C:	Solid
	Color:	White

Bulk properties
	Molecular weight (g/mol):	200,000-300,000 [1]

Occurence, isolation & synthesis

Occurence
Guar gum is derived from the endosperm of the guar bean from Cyamopsis tetragonolobus. Guar is grown in India (about 90%), Pakistan (about 5-10) and USA (Texas and Oklahoma) [8].

Isolation
The hull of the guar bean is softened by soaking in water and removed by grinding. Purification is accomplished by multistage grinding and sifting, separating the germ from the endosperm. The endosperm is ground to a powder called guaran [8].

History

Origin of name
From sanskrit gau = cow and aha = food [8].

References

1: Glicksman,M. Gum Technology in the Food Industry
(1969) Academic Press

2: Begin,F., Vachon,C., Jones,J.D., Wood,P.J., Savoie,L. Effect of Dietary Fibers on Glycemia and Insulinemia and on Gastrointestinal Function in Rats
Can. J. Physiol. Pharmacol. (1989) 67 1265-71

3: Lampe,J.W., Effertz,M.E., Larson,J.L., Slavin,J.L. Gastrointestinal Effects of Modified Guar Gum and Soy Polysaccharide as Part of an Enteral Formula Diet
J. Parenter. Enteral Nutr. (1992) 16 538-544

4: Ide,T., Moriuchi,H., Nihimoto,K. Hypolipidemic Effects of Guar Gum and its Enzyme Hydrolysate in Rats Fed Highly Saturated Fat Diets
Ann. Nutr. Metab. (1991) 35 34-44

5: Marchetti,M., Pisani,S., Pietropaolo,V., Seganti,L., Nicoletti,R., Orsi,N. Inhibition of Herpes Simplex Virus Infection by Negatively Charged and Neutral Carbohydrate Polymers
J. Chemother. (1995) 7 90-96

6: Do,N., Adams,R.P. A simple technique for removing plant polysaccharide contaminants from DNA
Biotechniques (1991) 10 162-166

7: Melito,C.A.U., Levy-Benshimol,A. Vegetable gums modify lectin hemagglutinability
Acta Cient. Venez. (1992) 43 312-314

8: Schoenberg,T., Chowdhary,M. Formulating with Quaternized Guar
Happi (2001) 38 (9) 90-93

9: Chandrasekaran,R., Bian,W., Okuyama,K. Three-dimensional structure of guaran
Carbohydr. Res. (1998) 312 216-224

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© Michael Pilgaard
Created: March 9, 2008