Optimization of prebiotic extraction from eremurus spectabilis (Serish) plant using ultrasonic assisted extraction method and investigation of prebiotic and biological activities

The aim of the thesis study was to optimize the extraction of inulin-type fructan obtained from the roots and leaf parts of the Serish (Eremurus spectabilis) plant through ultrasonically assisted extraction, to characterize its physicochemical properties, and to determine its prebiotic and biological activities. The extraction of inulin type fructan was optimized according to the response surface methodology, with the optimum extraction taking place under the conditions of 60°C, 1:12 g/mL, for 20 minutes, resulting in a yield of 44.94%, and the extracts were lyophilized. The polymerization degree of inulin type fructan ES was found to be 57±1, with a water solubility value of 89.8±1.18%, water holding capacity of 6.71±0.12 g/g, oil holding capacity of 4.80±0.01 g/g, moisture content of 6.18±0.12%, and swelling capacity of 2.6 mL/g. It was determined that inulin type fructan ES contains 39.39% fructose and 60.61% glucose in its structure, with monomers bound in the beta configuration. Additionally, it is anticipated that the extracted inulin type fructan ES can be used in industrial processes up to 205°C. Inulin type fructan ES, which was found to be resistant to gastric pH conditions, positively influenced the growth of Lactocaseibacillus rhamnosus ACS5, Pediococcus acidilactici 5008, and Saccharomyces cerevisiae BD21 strains, with their viabilities observed to be 9.58-9.95-9.62 log (CFU/mL) after 24 hours of fermentation, respectively. The highest prebiotic score activity was found to be 1.07 for the Lactocaseibacillus rhamnosus strain against Escherichia coli 11229. Inulin type fructan ES showed high antioxidant activity at low concentrations, with a gradual increase in antioxidant activity values as the concentration increased. It is believed that the ability to obtain high yield at minimum costs, positive effects on food applications and consumer health, fermentation by potential probiotic strains and low utilization by pathogenic microorganisms, resistance to stomach acid hydrolysis, and high antioxidant scavenging activity make E. spectabilis roots a natural, reliable source for industrial applications.