Amylose involvement in the amylopectin clusters of potato starch granules

The granular organization of common corn and potato starch is characteristically different. The objective of this study was to investigate iodine complex formation with starch lintners from common corn starch (CCS) and potato starch (PS) litners as a function of water content. Starches were subjected to mild acid hydrolysis (lintnerization). Size exclusion chromatography of the lintners indicated that the linear chains remaining after lintnerization had smaller degree of polymerization in PS lintners than in the corresponding CCS lintners. For both CCS and PS, the absorbance intensity and the wavelength of maximum absorption (λmax) of molecularly dispersed starches, in diluted iodine solution, decreased with increasing lintnerization extent. When the granular lintners were exposed to iodine vapor, following equilibration to different moisture contents, the reduction in the iodine binding was evident in PS lintners but not in CCS lintners. Furthermore, the iodination partially destroyed the crystallinity of native PS granules but not that of CCS granules. However, B-type crystallinity was still evident in PS lintners. This behavior was attributed to different location of amylose within starch granules, supporting the involvement of amylose in the B-type crystallites of PS, and the independence of amylose from the A-type crystallites of CCS.