Cereal Chem 38:34 - 46. | VIEW
Structure of the Starch Granule. II. Action of Various Amylases on Granular Starches.
H. W. Leach and T. J. Schoch. Copyright 1961 by the American Association of Cereal Chemists, Inc.
The dissolving action of various amylases on granular starches has been studied, with particular attention to bacterial alpha-amylase. The following starches are listed in order of increasing resistance to amylase: waxy maize, tapioca, waxy sorghum, sorghum, corn, wheat, rice, sago, arrowroot, potato, heat-moisture-treated potato, high-linear corn. Two general patterns of enzymatic solubilization were observed: A, extensive erosion and fragmentation of corn and sorghum starches and their waxy counterparts, and B, selective granule-by-granule destruction of potato and most of the other starches. Even after 50% solubilization of corn and sorghum starches, the fragmented residues have iodine affinities, intrinsic viscosities, Brabender viscosities, and swelling and solubility patterns similar to those of the parent starches. It is suggested that these cereal starches may have a porous granule structure accessible to the enzyme, while potato starch is less permeable. Other evidence indicates that the starch granule has no restrictive outer membrane, that the starch fractions are distributed uniformly throughout the granule, and that amylase action is not related to considerations of molecular association or crystallization pattern.