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Title: DETERMINATION OF THE BRANCHING RATIO IN STARCHES USING 1H HR MAS NMR SPECTROSCOPY

Author
item Himmelsbach, David
item Meadows, Frederick

Submitted to: European Experimental Nuclear Magnetic Resonance Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/11/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Proton high-resolution magic-angle spinning (1H HR MAS) NMR spectroscopy was used to determine the alpha-(1-4)/alpha-(1-6) branching ratio in starch as an accurate alternative to the starch-iodine determination of apparent amylose content. Both isolated starches and starches in rice flour were investigated. The branching ratio was determined by division of sum of the eintegrals of the linear, branched and non-reducing terminal protons by the integral of the signal due to the anomeric proton of the alpha-(1-6) branch. The 1H HR MAS experiments were conducted using both a wide bore 300 MHz NMR system with a modified CP/MAS probe and a narrow bore 500 MHz NMR system using a 1H/13C gradient HR MAS probe. Both MAS systems provided increased signal/noise over the comparable solution NMR method but with reduced resolution. It appears that 300 MHz NMR system is sufficient to make accurate determinations of the branching ratio in the case of in situ starches. Two-dimensional COSY and HSQC experiments were used to confirm assignments and are being used to investigate further interactions between proteins and lipids with starch in rice flour.