Extraction and identification of inulin-type fructo-oligosaccharides from Dahlia pinnata L.

A method for obtaining high yields of high-quality inulin from dahlia tubers was developed in the present study. The steps involved were the extraction of inulin, determination of inulin concentration and elucidation of inulin structure. The highest yield of inulin was obtained by ultrasonic- and microwave-assisted extraction (UMAE) (5.77 %), followed by stirring extraction (4.97 %) and indirect sonication (5.09 %). The concentrations of inulin extracted from dahlia tubers using UMAE were determined to be 41.94 % (w/w) and 33.52 % (w/w) by 3,5-dinitrosalicylic acid and high-performance liquid chromatography, respectively. Analysis of inulin extracted from dahlia tubers by Fourier-transform infrared spectroscopy confirmed the presence of an inulin-type fructan that is the same as commercial inulin. ¹H NMR and ¹³C NMR spectroscopy indicated that it has a degree of polymerization of 19-20 and a molecular weight of 3.173-3.316 Da.