Table 1.
Specifications of guar gum have been defined in Commission Regulation (EU) 231/2012 and by JECFA (2008). The available specifications are listed in Table 1. Commission Regulation No 231/2012/EC and JECFA specifications of guar gum (E 412) (JECFA, 2008a) and guar gum (clarified) (JECFA, 2008b)
| Regulation (EU) 231/2012 on guar gum | JECFA on guar gum (2008a) | JECFA on clarified guar gum (2008b) | |
|---|---|---|---|
| Definition | Guar gum is the ground endosperm of the seeds of natural strains of the guar plant, Cyamopsis tetragonolobus (L.) Taub. (family Leguminosae). Consists mainly of a high molecular weight hydrocolloidal polysaccharide composed of galactopyranose and mannopyranose units combined through glycosidic linkages, which may be described chemically as a galactomannan. The gum may be partially hydrolysed by either heat treatment, mild acid or alkaline oxidative treatment for viscosity adjustment | Primarily, the ground endosperm of the seeds from Cyamopsis tetragonolobus a (L.) Taub. (family. Leguminosae) mainly consisting of high molecular weight (50,000–8,000,000) polysaccharides composed of galactomannans; the mannose:galactose ratio is about 2:1. The seeds are crushed to eliminate the germ; the endosperm is dehusked, milled and screened to obtain the ground endosperm (native guar gum). The gum may be washed with ethanol or isopropanol to control the microbiological load (washed guar gum) |
Primarily, the ground endosperm of the seeds from Cyamopsis tetragonolobus (L.) Taub. (family Leguminosae) mainly consisting of high molecular weight (50,000–8,000,000) polysaccharides composed of galactomannans; the mannose:galactose ratio is about 2:1. The seeds are crushed to eliminate the germ; the endosperm is dehusked, milled and screened to obtain the ground endosperm (native guar gum). The gum is clarified by dissolution in water, filtration and precipitation with ethanol or isopropanol Clarified guar gum does not contain cell wall materials. Clarified guar gum in the market is normally standardised with sugars |
| MW | 50,000–8,000,000 | ||
| Assay | Galactomannan content not less than 75% | – | |
| Description | A white to yellowish‐white, nearly odourless powder | White to yellowish‐white, nearly odourless, free‐flowing powder | White to yellowish white, nearly odourless, free‐flowing powder |
| Functional uses | – | Thickener, stabiliser, emulsifier | Thickener, stabiliser, emulsifier |
| Identification | – | ||
| Tests for galactose and for mannose | Passes tests | – | |
| Solubility | Soluble in cold water | Insoluble in ethanol | Insoluble in ethanol |
| Gel formation | – | Add small amounts of sodium borate TS to an aqueous dispersion of the sample; a gel is formed | Add small amounts of sodium borate TS to an aqueous solution of the sample; a gel is formed |
| Viscosity | – | [test] | [test] |
| Gum constituents | – | Proceed as directed under Gum Constituents Identification using 100 mg of the sample instead of 200 mg and 1–10 μL of the hydrolysate instead of 1–5 μL. Use galactose and mannose as reference standards. These constituents should be present | Proceed as directed under Gum Constituents Identification using 100 mg of the sample instead of 200 mg and 1–10 μL of the hydrolysate instead of 1–5 μL. Use galactose and mannose as reference standards. These constituents should be present |
| Microscopic examination | – | [test] | – |
| Purity | |||
| Loss on drying | Not more than 15% (105°C, 5 h) | Not more than 15.0% (105°, 5 h) | Not more than 15.0% (105°, 5 h) |
| Ash | Not more than 5.5% determined at 800°C | Not more than 1.5% (800°, 3–4 h) | Not more than 1.0% (800°, 3–4 h) |
| Acid‐insoluble matter | Not more than 7% | Not more than 7.0% | Not more than 1.2% |
| Protein (N × 6.25) | Not more than 10% |
Not more than 10.0% Proceed as directed under Nitrogen Determination (Kjeldahl Method) in Volume 4 (under ‘General Methods, Inorganic components’). The percentage of nitrogen determined multiplied by 6.25 gives the percentage of protein in the sample |
Not more than 1.0% Proceed as directed under Nitrogen Determination (Kjeldahl Method) in Volume 4 (under ‘General Methods, Inorganic components’). The percentage of nitrogen determined multiplied by 6.25 gives the percentage of protein in the sample |
| Starch | Not detectable by the following method: to a 1 in 10 solution of the sample add a few drops of iodine solution (no blue colour is produced) | – | |
| Organic peroxides | Not more than 0.7 meq active oxygen/kg sample | – | |
| Furfural | Not more than 1 mg/kg | – | – |
| Pentachlorophenol | Not more than 0.01 mg/kg | ||
| Lead | Not more than 2 mg/kg |
Not more than 2 mg/kg Determine using an AAS/ICP‐AES technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the methods described in Volume 4 (under ‘General Methods, Metallic Impurities’) |
Not more than 2 mg/kg Determine using an AAS/ICP‐AES technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the methods described in Volume 4 (under ‘General Methods, Metallic Impurities’) |
| Arsenic | Not more than 3 mg/kg | – | – |
| Mercury | Not more than 1 mg/kg | – | – |
| Cadmium | Not more than 1 mg/kg | – | – |
| Borate | – |
Absent by the following test Disperse 1 g of the sample in 100 mL of water. The dispersion should remain fluid and not form a gel on standing. Mix 10 mL of dilute hydrochloric acid with the dispersion, and apply one drop of the resulting mixture to turmeric paper. No brownish red colour is formed |
Absent by the following test Disperse 1 g of the sample in 100 mL of water. The dispersion should remain fluid and not form a gel on standing. Mix 10 mL of dilute hydrochloric acid with the dispersion, and apply one drop of the resulting mixture to turmeric paper. No brownish red colour is formed |
| Residual solvents | – | Not more than 1% of ethanol or isopropanol, singly or in combination | Not more than 1% of ethanol or isopropanol, singly or in combination See description under TESTS |
| Microbiological criteria | – |
Test: Initially prepare a 10‐1 dilution by adding a 50 g sample to 450 mL of Butterfield's phosphate‐buffered dilution water and homogenising the mixture in a high‐speed blender Total (aerobic) plate count: Not more than 5,000 CFU/g E. coli: Negative in 1 g Salmonella: Negative in 25 g Yeasts and moulds: Not more than 500 CFU/g |
Initially prepare a 10‐1 dilution by adding a 50 g sample to 450 mL of Butterfield's phosphate‐buffered dilution water and homogenising the mixture in a high‐speed blender Total (aerobic) plate count: Not more than 5,000 CFU/g E. coli: Negative in 1 g Salmonella: Negative in 25 g Yeasts and moulds: Not more than 500 CFU/g |
AAS: atomic absorption spectroscopy; ICP‐AES: inductively coupled plasma atomic emission spectroscopy; CFU: colony‐forming units.
Current accepted name Cyamopsis tetragonoloba (ILDIS, 2013).