Abstract
Background: The acid extraction and enzymatic hydrolysis of starch followed by ion chromatography analysis are the tobacco industry standard methods in China which are very timeconsuming, troublesome, and moreover, there has no structure information of starch. This paper aims to develop an overall method for rapid extraction and simultaneous analysis of the content and structure of starch from flue-cured tobacco leaves by 13C CP/MAS NMR.
Methods: The starch from flue-cured tobacco was extracted using pH=10 NaOH solution with the ratio of liquid to solid 30:1 for 90 min and analyzed on the basis of solid state 13C NMR spectroscopy. Its crystalline characteristics, relative crystallinity, proportion of double helices and content were estimated by peak fitting analysis of C-1, C-2,3,5, C-4 and C-6 regions of the spectra.
Results: It was found that tobacco starch was B-type crystallinity and had the lowest double helix content and relative crystallinity compared with maize, sweet potato and lotus root starches. The quantitative result of internal standard method showed that the average recovery was 93.0% with the RSD of 3.2%~4.8%.
Conclusion: This rapid and accurate NMR method could provide important information about both amount and structure of starch in tobacco.
Keywords: NMR Spectroscopy, starch, polysaccharide, structural and quantitative analysis, flue-cured tobacco, hydrolysis.
Graphical Abstract
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