Granular cold-water soluble (GCWS) starch

Although the rationale for generating granular cold-water soluble (GCWS) and standard pregelatinized starches is similar (solubility/swelling without cooking), GCWS starches provide the added advantage of a retained granule structure, resulting in superior starch properties (Jane, 1995). Thus, the strategy associated with creation of GCWS starches involves disruption of the native granule crystallinity, while maintaining the starch in some degree of granular form. Industrially, GCWS starch is made by spray-cooking (Pitchon, O’Rourke, and Joseph, 1981) or heating in an aqueous alcohol slurry (Eastman and Moore, 1984; Rajagopalan and Seib, 1992). Other processes for generation of GCWS starches include treatment with liquid ammonia (Jackowski, Czuchajowska, and Baik, 2002; Baik and Jackowski, 2004) or suspension in alcoholic–alkaline solution (Chen and Jane, 1994a,b; Singh and Singh, 2003). By definition, granules remain intact, however, all processes used to generate GCWS starches report some degree of granular distortion, ranging from cracks, fissures, and indentations at granule surfaces to slight increases in granule size.

In general, GCWS starches exhibit a greatly reduced or a complete lack of both a gelatinization endotherm and native granule crystallinity, and no longer exhibit the characteristic polarization cross under planepolarized light. For GCWS starches prepared by heating aqueous alcohol slurries, double helices undergo transformation from the native crystalline packing arrangement to a V single-helix form, providing an explanation for the enhanced cold-water solubility of the modified products (Jane et al., 1986). Cold-water solubilities greater than 90% are reported for various GCWS starches (Jane et al., 1986; Chen and Jane, 1994a; Singh and Singh, 2003), and swelling powers as high as 15.3% have been observed, depending on the preparation process and the starch botanical source (Baik and Jackowski, 2004). Similar final viscosities are observed for GCWS and native corn starches subjected to pasting at 25°C and 95°C, respectively (Jane et al., 1986). Like conventional pregelatinized starches, pastes of GCWS starches have properties similar to those of their parent starches. Furthermore, properties of GCWS starches may be extended through various types of chemical modification.

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