Greener extraction of inulin from Jerusalem artichoke (Helianthus tuberosus L.) tubers: Optimization, purification and biological activity

Abstract

This study presents a green and efficient method for the extraction, optimization, purification, and structural characterization of inulin from Jerusalem artichoke using ultrasound-assisted extraction (UAE) with water as an eco-friendly solvent. The process of optimization via Response Surface Methodology (RSM) achieved a maximum inulin yield of 69.25% under conditions: solid-to-solvent ratio of 1:40 g/mL, extraction time of 120 min, and temperature of 60 °C. LC-MS analysis confirmed 97% purity with a degree of polymerization (DP) of 12. FT-IR and FT-NMR spectra identified characteristic β-(2 → 1) linkages, and XRD analysis revealed the amorphous nature of the product. FESEM showed agglomerated morphology, while EDS analysis indicated high carbon (56 wt%) and oxygen (43.4 wt%) content. In vitro Antibacterial activity assessed via agar well diffusion demonstrated dose-dependent inhibition of low DP inulin against E. coli, S. aureus, L. monocytogenes, and S. typhi, with maximum zones of inhibition at 50 mg/mL. This research presents a novel paradigm by illustrating how the degree of polymerization causes inulin to show direct in vitro antibacterial activity.

Keywords: Antibacterial; Characterization; Inulin; Jerusalem artichoke tuber; Optimization; Ultrasound-assisted extraction.