Properties of granular cold-water-soluble starches prepared by alcoholic-alkaline treatments. (1994)

Cereal Chem. 71(6):623-626 Granular cold-water-soluble (GCWS) starches were prepared from no detectable degradation of starch molecules during the preparation. normal maize, Hylon V (HA5), Hylon VII (HA7), and waxy maize starches The treated GCWS starches showed V-type X-ray diffraction patterns by treating the starches with mixtures of ethanol and NaOH solutions for normal maize, HA5, and HA7 starches; the GCWS waxy maize starch at a controlled temperature. No Maltese crosses appeared when the GCWS pattern was amorphous. The GCWS starches showed fully swollen starches prepared by these treatments were examined under polarized- granules when dispersed in cold water and exhibited -70-90% cold-water light microscopy, which indicated changes of crystalline structures. Gel- solubility. Most of the GCWS starches displayed higher viscosities and permeation chromatography analyses of the GCWS starches were identical better freeze-thaw stabilities than those of their native starch counterparts. with those of their native starch counterparts, which indicated there was Granular cold-water-soluble (GCWS) starches provide instant and greater viscosity and a smoother texture when -compared with drum-dried pregelatinized starch. Therefore, GCWS starches are desirable as ingredients of instant foods. GCWS starches also have more processing tolerance than traditional pregelatinized starches (Light 1990). GCWS starches can be prepared by several methods: 1) spray-drying (Pitchon et al 1981); 2) heating native starch in aqueous monohydric alcohol at 149-177'C under elevated pressure (Eastman and Moore 1984); 3) heating native starch in aqueous polyhydric alcohol at atmospheric pressure (Rajagopalan and Seib 1991, 1992a); 4) treating a slurry of native starch and a monohydric alcohol with an alkaline solution (Jane and Seib 1991, Chen and Jane 1994). The molecular structure and the properties of GCWS starch are of interest and have been investigated. GCWS starch prepared by high-temperature treatment of a starch-aqueous alcohol suspension displayed a V-type X-ray diffraction pattern (Jane et al 1986a,b). The mechanism proposed was that treating native starch with aqueous alcohol at high temperature converted the native double-helical structure into single helices. Removal of alcohol by drying left an empty cavity in the center of the helices, which resulted in starch granules that were metastable and coldwater-soluble. The GCWS starch is not chemically modified, but the processing caused a mild degradation of starch molecules. The paste viscosity of the GCWS starch is similar to that of its amylograph-cooked native starch counterpart. Rajagopalan and Seib (1992b) reported a V-type X-ray pattern of GCWS starches prepared by heating native starches in aqueous propan-1,2-diol at atmospheric pressure, but the X-ray pattern of hydroxypropylated cross-linked wheat starch was amorphous. Thickening and gelling properties of the GCWS starches prepared by heating starches in aqueous propan-1,2-diol at atmospheric pressure were similar to those of their native starch counterparts. Objectives of this study were to characterize the GCWS starches prepared by alcohol-alkaline treatments (Chen and Jane 1994) and to derive a mechanism of the GCWS starch formation. Molecular size distribution, viscosity, ash content, X-ray diffraction pattern, pasting property, and freeze-thaw stability of the resulting starches were investigated.