A Method for Estimating the Nature and Relative Proportions of Amorphous, Single, and Double-Helical Components in Starch Granules by¹³C CP/MAS NMR

Abstract

An improved method to analyze the (13)C NMR spectra of native starches, which considers the contribution of the V-type conformation and the nature of the amorphous component, has been developed. Starch spectra are separated into amorphous and ordered subspectra, using intensity at 84 ppm as a reference point. The ordered subspectra of high amylose starches show the presence of both V-type single helices and B-type double helices. Relative proportions of amorphous, single, and double-helical conformations are estimated by apportioning intensity of C1 peak areas between conformational types on the basis of ordered and amorphous subspectra of the native starch. Quantitative analysis shows that the V-type single-helical component increases with amylose content of starches. Different amorphous subspectra are needed to provide a consistent analysis of granular starches from diverse sources. The method of preparation was found to be more important than the starch botanical origin in determining (13)C NMR spectral features of amorphous samples.

Understanding the structural features of high-amylose maize starch through hydrothermal treatment

“…Both of the two starches were chemically unmodified; and their amylose contents were 56.3% and 82.9%, respectively, and their degrees of crystallinity were 31.3% and 28.3%, respectively [35][36], both as measured previously. 8-Aminopyrene-1,3,6-trisulfonic acid trisodium salt (APTS) and sodium cyanoborohydride were purchased from Sigma-Aldrich China (Mainland) (Shanghai, China).…”

Analysis of crystals of retrograded starch with sharp X-ray diffraction peaks made by recrystallization of amylose and amylopectin

“…According to Ref. [27], the C1 resonance is a triplet at 102, 101, and 100 ppm for the A-type crystalline polymorph, and a doublet at 101 and 100 ppm for B-type crystalline starch, but only one C1 resonances exists in Fig. 3; so, the crystalline pattern of retrograded sweet potato starch is different from those of A or B-type crystalline.…”

An improved approach for evaluating the semicrystalline lamellae of starch granules by synchrotron SAXS

“…WMS, RMS and GMS had amylose contents of ca. 3%, 24% and 56%, respectively, as measured using an iodine colorimetric method (Tan, Flanagan, Halley, Whittaker & Gidley, 2007). Potato starch (PS) (amylose content, ca.…”