Detection of solid-like components in starch using cross-relaxation and Fourier transform wide line proton NMR methods

Abstract

A new proton ('H) NMR method, nuclear magnetic cross-relaxation spectroscopy, permits sensitive detection of immobilized polymer in starch samples. The 'H cross-relaxation spectrum reflects the amount and relative rigidity of immobilized starch chains. Cross-relaxation integrated spectral intensities for freshly gelatinized waxy maize starch were found to depend sensitively on starch concentration above 10 wt ?4 . Retrogradation is observed to introduce a broad component to the cross-relaxation

1H magnetic cross‐relaxation between multiple solvent components and rotationally immobilized protein

“…The relaxation of most liquids in contact with proton-rich solid surfaces is profoundly influenced by the relaxation coupling between the protons of the solid spin system and that of the liquid even though the two populations experience vastly different dynamical regimes (3-7). Biological tissues and food materials provide particularly important proton-rich but dynamically heterogeneous materials (8)(9)(10)(11)(12)(13)(14). Indeed, the relaxation coupling between the liquid and solid components of tissue provides a means for changing the information content of a magnetic resonance image by using a pulse sequence that differentially changes the population of one component compared with the other (15)(16)(17).…”

Physical investigations of surface membrane–water relationship of intact and gelatinized wheat–starch systems

“…A similar behavior of the free water in a sucrose Á/starch system at higher a w and slow increase in tightly bound water was observed. 9 T 2i showed a decrease in relaxation time, indicating less mobile or free water molecules as the a w increased . The shortened relaxation times observed, supported elsewhere, 5 could be accounted for by a small fraction of water molecules hydrogen bonded to macromolecules.…”

Influence of composition of edible films based on gellan polymers on l-(+)-ascorbic acid stability

“…Hence, water populations determined in our work can be ascribed to retarded motion of water into the food polymer environment. According to Wu, Bryant, and Eads (1992), the 1 H NMR spectra for water-polymers systems revealed heterogeneity in proton mobility. Fitting a two component model has been reported to show that the proton mobility is dominated by the rigid components (from macromolecules) and mobile water protons.…”