Characterization of inulin from dahlia tubers isolated by microwave and ultrasound-assisted extractions
2018
Petkova, N. T. | Sherova, G. | Denev, P. P.
The “green” methods as microwave (MAE) and ultrasound-assisted extraction (UAE) have been applied for simultaneous isolation of inulin from dahlia tubers. The inulin yield was 42% dw, fructose content 90-95% and reducing groups was 4.3-4.6%, respectively. The structure of dahlia inulin was confirmed by IR-FT and 1 H and 13C NMR spectroscopy. IR-FT spectra showed brands at 817 and 873cm–1 assigned with β-(1→2) bond and proved the presenceof 2-ketofuranose, as well as bands at 937cm–1 typical for α-D-Glcp residue. The shifts at 103.6ppm in 13C NMR spectra confirmed the presence of β-(2→1)-D-Fruf residues in the linear chain of inulin. Therefore, isolated dahlia inulin consisted exclusively of (2→1)-linked β-fructofuranosyl, with terminal α-glucopyranosyl and β-fructofuranosyl units and the average degree of polymerization 19-23. MAE and UAE can be considered as appropriate approachesfor simultaneous extraction of high-molecular inulin from dahlia tubers with high purity (>97%).
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