|
Prepared at the 41st JECFA (1993), published in FNP 52 Add 2 (1993) superseding specifications prepared at the 39th JECFA (1992), published in FNP 52 Add 1 (1992) |
|
SYNONYMS |
INS No. 403 |
DEFINITION |
Ammonium salt of alginic acid. |
C.A.S. number |
9005-34-9 |
Chemical formula |
(C6 H11 NO6)n |
Structural formula |
Structural formula from Phillips, Wedlock and Williams: Gums and Stabilizers for the Food Industry 5 (1990) by permission of Oxford University Press.
The number and sequence of the Mannuronate and Glucuronate residues shown above vary in the naturally occuring alginate. The associated water molecules are not shown. |
Formula weight |
Structural unit: 193.16 (theoretical), 217 (actual average) Macromolecule: 32,000 - 250,000 (typical average) |
Assay |
Yields, on the dried basis, not less than 18.0% and not more than 21.0% of carbon dioxide (CO2), equivalent to not less than 88.7% and not more than 103.6% of ammonium alginate (C6H11 NO6)n. |
DESCRIPTION |
White to yellowish brown filamentous, grainy, granular or powdered forms |
FUNCTIONAL USES |
Stabilizer and thickener. |
CHARACTERISTICS | |
IDENTIFICATION | |
Solubility |
Dissolves slowly in water forming a viscous solution; insoluble in ethanol, ether and chloroform. |
Precipitate formation with calcium chloride |
To a 0.5% solution of the sample in sodium hydroxide TS add one-fifth of its volume of a 2.5% solution of calcium chloride. A voluminous, gelatinous precipitate is formed. This test distinguishes ammonium alginate from gum arabic, sodium carboxymethyl cellulose, carrageenan, gelatin, gum ghatti, karaya gum, carob bean gum, methyl cellulose and tragacanth gum. |
Precipitate formation with ammonium sulfate |
To a 0.5% solution of the sample in sodium hydroxide TS add one-half of its volume of a saturated solution of ammonium sulfate. No precipitate is formed. This test distinguishes ammonium alginate from agar, sodium carboxymethyl cellulose, carrageenan, de-esterified pectin, gelatin, carob bean gum, methyl cellulose and starch. |
Colour reaction |
Passes test Moisten 1-5 mg of the sample with water, and add 1 ml of acid ferric sulfate TS. Within 5 min, a cherry-red colour develops that finally becomes deep purple. |
Test for ammonium |
Passes test |
PURITY | |
Loss on drying |
Not more than 15% (105o, 4 h) |
Water-insoluble matter |
Not more than 1% on the dried basis Disperse 2 g of the sample, weighed to the nearest 0.1 mg, in 800 ml of water in a 2,000-ml flask. Neutralize to pH 7 with sodium hydroxide TS and then add 3 ml in excess. Add 40 ml of hydrogen peroxide solution containing 30% by weight H2O2, cover the flask and boil for 1 h with frequent stirring. Filter while hot through a tared Gooch crucible provided with a glass fibre filter (2.4 cm, No. 934 AH, Reeve Angel & Co., Clifton, N.Y., or equivalent filter). If slow filtration is caused by high viscosity of the sample solution, boil until the viscosity is reduced enough to permit filtration. Wash the crucible thoroughly with hot water, dry the crucible and its contents at 105o for 1 h, cool and weigh. Calculate as percentage of the dry weight. |
Total ash |
Not more than 4% on the dried basis |
Arsenic |
Not more than 3 mg/kg (Method II) |
Lead |
Not more than 10 mg/kg Prepare a sample solution as directed for organic compounds in the Limit Test, using 10 µg of lead ion (Pb) in the control |
Heavy metals |
Not more than 40 mg/kg Test 0.5 g of the sample as directed under the Limit Test (Method II) |
METHOD OF ASSAY |
Proceed as directed under Carbon Dioxide Determination by Decarboxylation. Each ml of 0.25 N sodium hydroxide consumed is equivalent to 5.5 mg of carbon dioxide (CO2) or 27.12 mg of ammonium alginate (equivalent weight 217). |