Microwave-Assisted Isolation and Acetylation of Inulin from Helianthus Tuberosus L Tubers

Jerusalem artichoke (Helianthus tuberosus L.) tubers are industrial crop considered as a promising source for inulin production. “Green” method was performed for accelerated inulin extraction from Helianthus tuberosus L. tubers by the application of microwave irradiation. Further pretreatment of the water extract with acetone and ethanol yielded inulin (20%) with purity 89% and degree of polymerization 18. Jerusalem artichoke inulin was characterized by FTIR and NMR spectroscopy. For the first time eco-friendly synthesis of acetylated Jerusalem artichoke inulin was performed by the reaction with acetic anhydride, without toxic solvent, but only with sodium acetate as catalyst under microwave irradiation for 60 s. The degree of acetylation (DA=2.1) and the structure of inulin esters were confirmed by 1H and 13C NMR. The suggested microwave acetylation shortens significantly the esterification reaction.