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The Effects of Amylose and Starch Phosphate on Starch Gel Retrogradation Studied by Low‐field 1 H NMR Relaxometry
Author(s) -
Thygesen Lisbeth G.,
Blennow Andreas,
Engelsen Søren B.
Publication year - 2003
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.200390062
Subject(s) - amylose , amylopectin , chemistry , retrogradation (starch) , relaxometry , starch , phosphate , food science , chromatography , analytical chemistry (journal) , nuclear chemistry , crystallography , biochemistry , medicine , spin echo , magnetic resonance imaging , radiology
Low‐field Nuclear Magnetic Resonance (23 MHz) was used to study the effects of the degree of phosphorylation, the amylose content and the amylopectin chain length distribution on gel retrogradation for a set of 26 starches, six of which were of crystal polymorph type A, 18 of type B and two of type C. The phosphate content ranged from 0 to 58.8 nmol Glc6P/mg and the amylose content from 0 to 72.1%. The starch pastes (13%, w/w) were measured before and after storage for six days at 35 °C. It was found that Principal Component Analysis (PCA) of the raw Carr‐Purcell‐Meiboom‐Gill (CPMG) relaxation curves from the two measurements (day 1 and day 7) could be used as a simple, illustrative way of describing the retrogradation. Three different behaviours were identified: One group of samples (mostly potato starches) slowly changed from a soft to a more rigid gel from day 1 to 7. A second group (mostly cereal starches) formed a rigid gel already before the first measurement and changed little after that. A third group comprised a few samples containing little or no amylose aged similarly to the first group of samples, but at a much slower rate. For the potato starches, a weak negative correlation ( r = ‐0.63) was found between the degree of phosphorylation and the difference between the LF NMR relaxation curves of day 1 and day 7.