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- Nilsson, Gunilla S., et al.
(author)
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Determination of the degree of branching in normal and amylopectin type potato starch with 1H-NMR spectroscopy : Improved resolution and two-dimensional spectroscopy
- 1996
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In: Starch/Staerke. - : Wiley. - 0038-9056 .- 1521-379X. ; 48:10, s. 352-357
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Journal article (peer-reviewed)abstract
- Starch from genetically modified potatoes was found to be highly branched compared with normal potato varieties through the use of 1H-NMR spectroscopy. The average chain length, blue-value,and the wavelength at maximum absorptivity clearly show that the new potato varieties produce amylopectin starch. Correlation between the degree of branching as determined by 1H-NMR and starch-iodine complexation, expressed as blue-value, was good and the NMR-method gives low standard deviation. For the first time, the anomeric proton, H-I, of a (1→4)-α-linked D-glucose residue and the H-I of the glucose residue of a non-reducing end have been assigned separate chemical shifts in starch. Assignments were made as determined from two-dimensional homonuclear and 1H-13C heteronuclear spectroscopy (COSY, HMQC, and HMBC). The molecular weight in degraded starch and pullulan were determined by means of NMR-spectroscopy. These results were in accordance with determinations by size exclusion chromatography and with the known molecular weights of pullulan standards.
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