Sodium carboxymethyl cellulose is a natural cellulose by chemical modification and obtained a high polymer fiber ether, its structure is mainly D glucose unit by beta ( 1, 4) are formed by the connection of the glycosidic bond. The main reaction : natural cellulose first with NaOH alkalization reaction, with chloroacetic acid to join, the glucose unit on the hydroxyl hydrogen and chlorine acetic acid by carboxymethyl group substitution reaction.
From the structure type can be seen in each glucose unit had a total of 3 hydroxyl groups, i.e. C2, C3, C6 hydroxyl, glucose unit the hydroxyl hydrogen by Carboxymethyl substitution the number of substitution degree, if each unit on the 3 hydroxyl hydrogen were carboxymethyl substituents, defined as the degree of substitution is in 3, CMC substitution degree directly affects the size of the CMC solubility, emulsifying property, thickening property, stability, acid resistance and salt resistance and other properties. Is generally believed that the degree of substitution in 0.6 to about 0.7 when the emulsion has good performance, and with the increase of the degree of substitution, other properties corresponding to be improved, when the degree of substitution is greater than 0.8, the acid resistance, salt resistance performance was significantly enhanced. In addition, it is also mentioned in each unit had a total of 3 hydroxyl groups, namely C2, C3 secondary hydroxyl groups and C6 primary hydroxyl, theory on the primary hydroxyl group activity is greater than the secondary hydroxyl groups, but according to C C2 parity effect, the OH base more acidic, especially in alkali environments than C3, its vitality C6 is stronger, so more susceptible to substitution reaction, C6, C3 weakest. In fact, CMC performance not only with the degree of substitution on the size, but also with carboxymethyl groups in the cellulose molecule distribution uniformity and each molecule hydroxymethyl in each cell and C2, C3, C6 substituted heterogeneity related. Because CMC is a high polymerization linear compounds, and the carboxymethyl in molecules in the presence of substituted inhomogeneity, so when the solution when standing molecules in the presence of different orientation, when the solution of shear stress exists, its linear molecular long axis to the flow direction of the trend, and with the increase of shear rate this trend more strong, until finally completely aligned so far, this characteristic of CMC called fake plastic. CMC pseudo plasticity is beneficial to reduce the energy consumption of liquid milk production, in favor of homogeneous and pipeline transportation, in liquid milk doesn't taste too greasy, conducive to milk liquid aroma release.
CMC and other various stabilizers ( yellow gum, guar gum, sodium alginate, carrageenan, starch, gelatin, maltodextrin, ) is used in combination with synergism. In addition of sodium citrate and chelated salt can enhance its viscosity. CMC and other stabilizing synergistic effect of a table.
Along with the CMC technology, CMC substitution degree up to 1 or more, and replace the uniformity is improved, CMC acid, salt resistance has been greatly improved, CMC is not only a single application in neutral food, acid CMC is widely used in acid, sugar and salt in food, especially in the acidified milk drinks.
