Structural analysis of novel kestose isomers isolated from sugar beet molasses

•Eight kestose isomers were isolated from sugar beet molasses.•The structures of the kestose isomers were confirmed using NMR techniques.•Five of eight kestoses were novel oligosaccharides. [Display omitted] Eight kestose isomers were isolated from sugar beet molasses by carbon–Celite column chromatography and HPLC. GC–FID and GC–MS analyses of methyl derivatives, MALD-TOF-MS measurements and NMR spectra were used to confirm the structural characteristics of the isomers. The 1H and 13C NMR signals of each isomer saccharide were assigned using COSY, E-HSQC, HSQC–TOCSY, HMBC and H2BC techniques. These kestose isomers were identified as α-D-fructofuranosyl-(2- > 2)-α-D-glucopyranosyl-(1 2)-β-D-fructofuranoside, α-D-fructofuranosyl-(2- > 3)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside, α-D-fructofuranosyl-(2- > 4)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside, β-D-fructofuranosyl-(2- > 4)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside, β-D-fructofuranosyl-(2- > 3)-α-D-glucopyranosyl-(1 2)-β-D-fructofuranoside, α-D-fructofuranosyl-(2- > 1)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside, α-D-fructofuranosyl-(2- > 6)-α-D-glucopyranosyl-(1 2)-β-D-fructofuranoside, and α-D-fructofuranosyl-(2- > 6)-β-D-fructofuranosyl-(2 1)-α-D-glucopyranoside. The former five compounds are novel saccharides.