E 469 ENZYMATICALLY HYDROLYSED CARBOXYMETHYLCELLULOSE

Commission Directive 2000/63/EC

Synonyms Sodium carboxymethyl cellulose, enzymatically hydrolysed

Definition Enzymatically hydrolysed carboxymethylcellulose is obtained from carboxymethylcellulose by enzymatic digestion with a cellulase produced by Trichoderma longibrachiatum (formerly T. reesei)

Chemical name Carboxymethyl cellulose, sodium, partially enzymatically hydrolysed

Chemical formula Sodium salts of polymers containing substituted anhydroglucose units with the general

formula:
[C₆H₇O₂(OH)_x(OCH₂COONa)_y]_n
where n is the degree of polymerisation
x = 1,50 to 2,80
y = 0,2 to 1,50

x + y = 3,0
(y = degree of substitution)

Formula weight 178,14 where y = 0,20

282,18 where y = 1,50

Macromolecules: Not less than 800 (n about 4)

Assay Not less than 99,5 %, including mono- and disaccharides, on the dried basis

Description White or slightly yellowish or greyish, odourless, slightly hygroscopic granular or fibrous powder

Identification

A. Solubility Soluble in water, insoluble in ethanol

B. Foam test Vigorously shake a 0,1 % solution of the sample. No layer of foam appears. This test distinguishes sodium carboxymethyl cellulose, whether hydrolysed or not, from other cellulose ethers and from alginates and natural gums

C. Precipitate formation To 5 ml of a 0,5 % solution of the sample add 5 ml of a 5 % solution of copper or aluminium sulphate. A precipitate appears. This test distinguishes sodium carboxymethyl cellulose, whether hydrolysed or not, from other cellulose ethers and from gelatine, carob bean gum and tragacanth gum

D. Colour reaction Add 0,5 g of the powdered sample to 50 ml of water, while stirring to produce a uniform dispersion. Continue the stirring until a clear solution is produced. Dilute 1 ml of the solution with 1 ml of water in a small test tube. Add 5 drops of 1-naphthol TS. Incline the tube, and carefully introduce down the side of the tube 2 ml of sulphuric acid so that it forms a lower layer. A red-purple colour develops at the interface

E. Viscosity (60 % solids) Not less than 2,500 kgm^-1s^-1 at 25 °C corresponding to an average molecule weight of 5000 D

Purity

Loss on drying Not more than 12 % (105 °C to constant weight)

Degree of substitution Not less than 0,2 and not more than 1,5 carboxymethyl groups per anhydroglucose unit on the dried basis

pH of a 1 % colloidal solution Not less than 6,0 and not more than 8,5

Sodium chloride and sodium glycolate Not more than 0,5 % singly or in combination

Residual enzyme activity Passes test. No change in viscosity of test solution occurs, which indicates hydrolysis of the sodium carboxymethyl cellulose

Lead Not more than 3 mg/kg