Partially oxidized potato starches from bromide-free TEMPO-mediated reaction: characterization of monosaccharide composition.

摘要

Partially oxidized starches were obtained by oxidation of water-soluble potato starch with the NaOCl/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) system in the absence of bromide in aqueous solutions at pH 10.2. Monosaccharide composition of the oxidized starches was studied by acid-base titration and NMR spectroscopy, and it was characterized by a content of B units with carboxyl groups (7-73 mol%), C units with C-6-aldehyde hydrate groups (5-37%), and non-oxidized A units (20-88%). The feature of bromide-free TEMPO-mediated oxidation of starch was the formation of a significant amount of C units. In addition to monosaccharide composition, compositional heterogeneity of a starch sample with 73% of B units was described by the distribution of triad sequences BBB (54 mol%), ABA (20%), AAB + BAA (12%) and BAB (14%), which were quantified by NMR spectroscopy. copyright 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.