Extraction, purification and structural characterization of inulin-type fructans from different selected Asparagus species

Inulin is a naturally occurring fructose polysaccharide and soluble dietary fiber, found in various plants, commonly used in the food industry for its excellent prebiotic properties and as a fat or sugar substitute. Commercial inulin is largely extracted from Chicory plant, which is grown only in temperate parts of the world. This study chemically and structurally investigated the potential of four Asparagus species A. falcatus, A. racemosus, A. officinalis, and A. gonocladus as alternative inulin sources for the food industry. Inulins were extracted using either hot water extraction or microwave-assisted extraction. Asparagus inulin powders were analyzed for inulin content, total phenolics, total flavonoids, radical scavenging activity and mineral composition. A. falcatus, A. gonocladus and A. racemosus fresh roots contained considerably high inulin contents (23.61 ± 1.04, 17.08 ± 2.58, 12.22 ± 1.51 % FW, respectively). The highest inulin content in their powders (92.31 ± 2 0.89 %) was shown by microwave-assisted extracted A. gonocladus inulin powder. The molecular structure and phase behavior of inulin contained in roots of Asparagus were confirmed by FTIR and XRD respectively, and the thermal behavior was confirmed by DSC data. The results suggest that Asparagus inulin possesses significant potential for use in food applications as an alternative inulin source.