Title
TEMPO oxidation of gelatinized potato starch results in acid resistant blocks of glucuronic acid moieties
Author
ter Haar, R.
Timmermans, J.W.
Slaghek, T.M.
van Dongen, F.E.M.
Schols, H.A.
Gruppen, H.
TNO Kwaliteit van Leven
Publication year
2010
Abstract
Chemical derivatization is often applied to improve polysaccharide functionality. Primary hydroxyl groups in starch can, for example, be oxidized to aldehydes by using a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated reaction. The major part of the aldehydo groups is subsequently converted to carboxyl groups by NaOCl. The exact structure of TEMPO-oxidized starch was studied to promote a better understanding of the TEMPO oxidation mechanism and the functionality of oxidized starches. By using weak and strong acidic hydrolysis, and methanolysis, at elevated temperatures, oxidized starches with different degrees of oxidation (DO) were broken down into oligomers and monomers. Analysis of the oligomers by chromatographic and mass spectrometric techniques revealed that blocks of glucuronic acid moieties are present in the oxidized starch polymers. The α(1 → 4) glucuronic acid-glucuronic acid bond was found to be very resistant to breakdown by acids. The α(1 → 4) glucuronic acid-glucose bond also showed increased resistance to acids compared to α(1 → 4) glucose-glucose bonds. The size of the blocks of glucuronic acid moieties increased when DO increased. Furthermore, the presence of clusters of aldehydes close to carboxyl groups directly after oxidation was proven. This implies that TEMPO, which is positively charged in its active state, is apparently attracted by the negatively charged carboxyl groups. Because of this, TEMPO tends to be active in areas where carboxyl groups have already been formed, which leads to a block wise distribution of the glucuronic acid moieties. © 2010 Elsevier Ltd. All rights reserved.
Subject
Biology
Food and Chemical Risk Analysis
Acidic hydrolysis
Acidic methanolysis
Glucuronan
Potato starch
TEMPO oxidation
To reference this document use:
http://resolver.tudelft.nl/uuid:cb896021-9951-406f-83a9-44e9d4245897
TNO identifier
360805
ISSN
0144-8617
Source
Carbohydrate Polymers, 81 (4), 830-838
Document type
article