Conventional and unconventional recovery of inulin rich extracts for food use from the roots of globe artichoke

Inulin is a prebiotic, recovered from several vegetable sources, used for its health-promoting and technological properties. In this study, inulin was extracted from artichoke roots, an emerging agricultural waste, using both hot-water and ultrasound-assisted extraction. Roots from five cultivars grown in three different sites were submitted to both hot water extraction and ultrasound-assisted extraction. Physic-chemical characterization of the extracts was carried out, and gelling and prebiotic properties were evaluated. The extraction yields of the artichoke roots ranged between 6.5 and 20.9 g 100 g−1, and the use of ultrasound led to an increase in yield only for two cultivars. The FT-IR spectra of the extracts were comparable to that of commercial inulin from chicory, whereas the average degree of polymerization was higher (32 DP). Furthermore, extracts provided gels with different hardness. In most cases, the ultrasound-assisted method increased the protein residue of extracts and reduced the antiradical activity and the gel hardness. The evaluation of the prebiotic properties showed that almost all the tested probiotic strains were able to grow on artichoke inulin although with different extents. The results of this study suggest that artichoke roots can be a suitable source of inulin, though the extraction technology, the genetic and pedoclimatic variables can severely affect yields, gelling properties and prebiotic activity of inulin extracts.