Cold-water-soluble starch

Figure 10.5 Scanning electron micrographs (a b) showing granular indentation and fragmentation in granular cold water-soluble starches (source Singh and Singh, 2003).

Rajagopalan, S., Seib, P. A. (1992). Properties of granular cold-water soluble starches prepared at atmospheric pressure. J. Cereal Set, 16,29 0. 

Tapioca starch and chemically modified tapioca starches are easily converted to instant (pregelatinized) forms (also known as cold-water-soluble starch). This physical modification is brought about by pasting of the starch and subsequent drying as described in Section 12.4. Control of particle size is critical to texture and rehydration rate when the product is redispersed in water.68 Fine particle size results in a smooth texture on redispersion, e.g. in pudding preparation.69 As a comparison, coarse texture could be more desirable in fruit- or vegetable-based foods. 

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

STARAMIC Starches are pregelatinized, cold water soluble starches that fill a number of application needs in various industries—in ceramics, paper and textiles, in building materials, paints and molded pulp products. 

The Water Unextractable Solids were isolated from dehulled, defatted, untoasted soy bean meal (particle size < 0.5 mm) by removal of cold water solubles, proteins and starch. The soy bean meal was extracted with cold water, a solution containing sodium dodecylsulphate and 1,4-dithiothreitol, and incubated with a-amylase, to yield the CWS, SDSS and HWS... 

The yield and the composition of the fractions from soy bean meal obtmned with isolating WUS is shown in Table 1. The removal of cold water solubles, proteins and starch from soy meal was successful. The larger part of the material appeared in CWS, 59.1%. UFF contained mainly oligosaccharides and some water soluble proteins and UFR contained mainly water soluble proteins. The solution of SDSS and DTT extracted the residual proteins from the soy meal and the extract consisted for over 80% of proteins. Since the yield of the HWS fraction is only 0.4%, the composition is not discussed here. The remaining WUS contained 90% of NSP and the yield was 15.7%, which indicates that from the polysaccharides present in soy meal 92% was recovered in the WUS. By isolating WUS a fraction is obtained in which almost all cell wall polysaccharides are recovered and which contained only little other components. 

Retrogradation is the reassociation of solubilized starch polymers in their native state or those in dextrins or in low-DE hydrolyzates resulting in an insoluble precipitate. Dextrins are depolymerized starches produced by heating a starch moistened with dilute hydrochloric acid or heating a moist starch in the presence of gaseous hydrogen chloride until a cold-water-soluble product is formed. 

Note The treatment outlined above is satisfactory for starch products that are insoluble in cold water. For pregelatinized starch and other water-soluble starches, prepare a 1% to 2% aqueous paste, place it in a cellophane tube, and dialyze against running distilled water for 30 h to 40 h. Precipitate the starch by pouring the solution into 4 volumes of acetone per volume of paste while stirring. Recover the starch by vacuum filtration in a medium-porosity fritted-glass or Buchner funnel, and wash the filter cake with absolute ethanol. Dry the filter cake, and determine the amount of dry substance as directed for water-insoluble starches. 

Pregelatinized starch 0.1-0.5 Cold-water soluble so easier to prepare than starch... 

HAMACO cold-water soluble corn starches are used as thickeners and binders for a variety of applications. They offer rapid and complete dispersion without lumping, and are extremely stable for long periods of storage. 

STADEX Dextrins are partially hydrolyzed starches that are prepared by heating or dry roasting starch in the presence of an acid catalyst. The conversion process - the change from starch to dextrin - changes the properties of the parent starch in several ways. Notably, the dextrin exhibits a thinner cooked-paste viscosity, an increased cold water solubility, and a color change from white to off-white or yellow. 

Within the three STARAMIC "families" 300, 600, and 700— a broad, controlled range of viscosities, particle sizes, and cold water solubilities are available. Individually, each starch exhibits outstanding film-forming characteristics and exceptional adhesive qualities. 

In the case of the White dextrins, pyrolysis induces an apparent hydrolytic reaction, because, with time, there is a steady increase in reducing power and cold-water solubility and a steady decrease in viscosity. These characteristic changes are shown in Fig. 1. Pastes made from such dextrins show gelation, or set-back, properties comparable to those of the original starch. 

Determine the boric acid in the cold water-soluble portion by titration in the presence of 50 per cent of glycerol with 0-5N alkali to phenol-phthalein or phenol violet. To the residue add dilute hydrochloric acid, heat to boiling and filter. Wash, dry the talc at 105° and weigh. Determine the zinc in the acid filtrate by titration (p. 696). The starch figure is usually obtained by difference, but may be assayed using the cold hydrochloric acid method described under Starch (p. 577) which gives a close approximation. 

Singh, J. and Singh, N. (2003) Studies on the morphological and rheological properties of granular cold water soluble com and potato starches. Food Hydrocolloids 17 (1) 63-72. 

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