Functionality of starch granules in milling fractions of normal wheat grain

Normal wheat grains were milled into nine fractions (A-I) ranging from the surface layer to the center of a grain with a modified machine used for polishing brewers' rice. Starch granules were isolated from the fractions in this study. Amylose content and functionality of the starches, hydrolysability with enzyme, gelatinization and retrogradation properties, swelling power and freeze-thaw stability of gels of starches were investigated. The results indicated that the apparent amylose content was similar among wheat fraction starches, but the structures and the functionalities of the starches differed with location of the grain. Starch granules from the surface were hydrolyzed and gelatinized easily, and swelled little compared with those from the center. The gel from the starches of the center was more stable in freeze-thawing than those from the surface, and more difficult to retrograde. These findings may provide important information to utilize the classified wheat flours produced by the new method.