Cold-water-swellable starch

Granular Cold-Water-Swellable (CWS) and Cold-Water-Soluble Starch (Pregelatinized Granular Starch)... 

Gums. Gums are hydrophobic or hydrophilic polysaccharides derived from plants or microorganisms that upon dispersing in either hot or cold water produce viscous mixtures or solutions (i.e., gels (1)). As used in the modern sense, the term gum includes any water-soluble or water-swellable polysaccharide or its derivative. This includes starch and dextrins and various derivatives of cellulose. The latter, however, are considered separately. 

Heating of starch suspensions, followed by drying, provides products that are swellable in cold water and form pastes or gels on heating. These products are used in instant foods, e. g., pudding, and as baking aids (cf. Table 4.26). 

The reaction will proceed in aqueous suspension, but the ether formed becomes swellable in cold water if DS becomes >0.1. Therefore, the process is mostly run in aqueous organic solvents such as methanol, ethanol, isopropanol, acetone. After the reaction, the unswollen and undissolved c. is filtered off, washed and dried. Usually DS is 0.2-0.6. Carboxymethylation enhances die hydrophilic character of - starch polysaccharides (- anionic starch). 

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