Cereal Chem 69:405-409 | VIEW
ARTICLE
Location of Amylose in Normal Starch Granules. I. Susceptibility of Amylose and Amylopectin to Cross-Linking Reagents.
J. Jane, A. Xu, M. Radosavljevic, and P. A. Seib. Copyright 1992 by the American Association of Cereal Chemists, Inc.
When granular starch was cross-linked, more amylopectin than amylose molecules were found cross-linked. For example, when corn starch was treated with cross-linking reagent (0.07% epichlorohydrin) (pH 10.5 for 24 hr), 91% of its amylopectin and 45% of its amylose became insoluble. Cross-linking of pregelatinized and dispersed starch caused less difference in the proportion of soluble amylose and amylopectin than did the cross-linking of native granular starch. After the starch had been cross-linked in the granular form, gel- permeation chromatograms showed no increase in the size of amylose as a result of cross-linking between two or more amylose molecules. However, susceptibility of the amylose to sequential hydrolysis by isoamylase and beta-amylase decreased. The relative blue values of amylopectin peaks indicated that amylose was cross-linked to amylopectin. This was confirmed when the amylopectin isolated from cross- linked starches was debranched with isoamylase. These results are consistent with the view that amylose is interspersed among amylopectin molecules in corn and potato starch granules.