Alginate monomer composition studied by solution- and solid-state NMR - A comparative chemometric study

作者：Salomonsen Tina^*; Jensen Henrik Max; Larsen Flemming Hofmann; Steuernagel Stefan; Engelsen Soren Balling

来源：Food Hydrocolloids, 2009, 23(6): 1579-1586.

DOI：10.1016/j.foodhyd.2008.11.009

• Alginate
• Calcium
• Nuclear magnetic resonance
• CP-MAS NMR
• HR-MAS NMR
• Chemometrics

The potential of using 1 H high-resolution (HR) magic angle spinning (MAS) nuclear magnetic resonance (NMR) of alginates suspended in D(2)O or (13)C cross-polarisation (CP) MAS NMR of alginate powders as an alternative method to the traditional (1)H solution-state NMR method for the analysis of the alginate monomer composition (mannuronate (M)/guluronate (G) ratio) has been investigated. The MAS NMR experiments can be performed directly on the intact alginate powders and thereby avoiding the relatively time-consuming and]about intensive sample preparation required for the traditional solution-state experiment. A total of 42 different sodium alginate samples were analysed and it was found that the M/G ratio derived from the HR-MAS NMR spectra were comparable to the M/G ratio calculated from the solution-state NMR spectra. However, both these methods overestimated the M/G ratio of samples with high calcium content. In contrast, the (13)C CP-MAS NMR spectra were not affected by residual calcium in the samples and thus Provided more consistent measurements independent on physico-chemical phenomena Such as partial solubility, viscosity and interactions with ions. It is concluded that (13)C CP-MAS NMR is a most suitable candidate for accurate analysis of the M/G ratio of intact alginate powders.

• 出版日期2009-8