:Part 2. Reaction of Epichlorohydrin with Corn Starch

概要

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Although epichlorohydrin has been used as one of the most common cross-bonding reagents of starch, to inhibit swelling of starch granules during cooking, only a little is known about the relation between physical properties of cross-bonded starch and the site of crossbonding in starch molecule. The samples of various degree of cross-bonding in the range of 1 cross-bonding/110 AGU-1 cross-bonding/2300 AGU were prepared by the reaction of epichlorohydrin with corn starch at room temperature. The reaction efficiency of epichlorohydrin was about 70%. There were good relationships between the degree of cross-bonding and the absorbance at 95°C of photopastegrams, and also swelling power at 100°C. In order to determine the site of the cross-bonding in starch molecule, the samples were treated with exo-amylases, then the limits of the hydrolysis were determined. The extent to which cross-bonded starch was hydrolyzed by exo-amylases was greatly decreased depending upon the degree of cross-bonding produced. Therefore, it may be concluded that the decrease in the hydrolysis extent of starch by the enzymes is due to inability of starch to swell as well as to insusceptibility of starch to the enzyme by formation of the cross-bondings, presumably at the nonreducing ends of starch molecules.
日本応用糖質科学会の論文