COMMISSION REGULATION (EU) No 231/2012 of 9 March 2012
E 400 ALGINIC ACID
Linear glycuronoglycan consisting mainly of β-(1-4) linked D-mannuronic and α-(1-4) linked L-guluronic acid units in pyranose ring form. Hydrophilic colloidal carbohydrate extracted by the use of dilute alkali from strains of various species of brown seaweeds (Phaeophyceae)
Chemical formula: (C 6 H 8 O 6 ) n
Molecular weight: 10 000-600 000 (typical average)
Assay: Alginic acid yields, on the anhydrous basis, not less than 20 % and not more than 23 % of carbon dioxide (CO 2 ), equivalent to not less than 91 % and not more than 104,5 % of alginic acid (C 6 H 8 O 6 ) n (calculated on equivalent weight basis of 200)
Alginic acid occurs in filamentous, grainy, granular and powdered forms. It is a white to yellowish brown and nearly odourless
Solubility: Insoluble in water and organic solvents, slowly soluble in solutions of sodium carbonate, sodium hydroxide and trisodium phosphate
Calcium chloride precipitation test: To a 0,5 % solution of the sample in 1 M sodium hydroxide solution add one fifth of its volume of a 2,5 % solution of calcium chloride. A voluminous, gelatinous precipitate is formed. This test distinguishes alginic acid from acacia gum, sodium carboxymethyl cellulose, carboxymethyl starch, carrageenan, gelatin, gum ghatti, karaya gum, locust bean gum, methyl cellulose and tragacanth gum.
Ammonium sulphate precipitation test: To a 0,5 % solution of the sample in 1 M sodium hydroxide solution add one half of its volume of a saturated solution of ammonium sulphate. No precipitate is formed. This test distinguishes alginic acid from agar, sodium carboxymethyl cellulose, carrageenan, de-esterified pectin, gelatin, locust bean gum, methyl cellulose and starch.
Colour reaction: Dissolve as completely as possible 0,01 g of the sample by shaking with 0,15 ml of 0,1 N sodium hydroxide and add 1 ml of acid ferric sulphate solution. Within 5 minutes a cherry-red colour develops that finally becomes deep purple.
pH: Between 2,0 and 3,5 (3 % suspension)
Loss on drying: Not more than 15 % (105 °C, 4 hours)
Sulphated ash: Not more than 8 % on the anhydrous basis
Sodium hydroxide (1 M solution) insoluble matter: Not more than 2 % on the anhydrous basis
Formaldehyde: Not more than 50 mg/kg
Arsenic: Not more than 3 mg/kg
Lead: Not more than 5 mg/kg
Mercury: Not more than 1 mg/kg
Cadmium: Not more than 1 mg/kg
Total plate count: Not more than 5 000 colonies per gram
Yeast and moulds: Not more than 500 colonies per gram
Escherichia coli: Absent in 5 g
Salmonella spp.: Absent in 10 g