Green approach in saponin extraction from Acanthophyllum caryophyllaceae root based on ultrasonication coupled with solvent extraction method and its lyophilization

Saponin, as nonionic emulsifier, has been broadly used in food products and formulations, such as ice cream, chocolates, mayonnaises and bakery food. Acanthophyllum caryophyllaceae root is known as Chubak in Iran and is one of the main sources of saponin. In the present study, saponin was extracted from dried A. caryophyllaceae root using hydro-alcoholic solvent in combination to ultrasonication. UV-Vis spectroscopy indicated that pure and extracted saponin (ES) had absorbance at 520 nm. Effects of the ethanol percentage in the hydro-alcoholic solution (10 to 80% V/V) and ultrasonication time (10 to 20 min) on the absorbance, emulsification index and antioxidant activity of the colloidal solution containing ES were evaluated. Colloidal solution with maximum absorbance (0.157% a.u), emulsification index (0.588) and antioxidant activity (25.55%), was obtained using optimum amount of ethanol in solvent and sonication time of 34% and 13 min, respectively. Finally, lyophilized saponin was prepared using colloidal solution having saponin with concentration of 1.4% W/V, and characterized by DLS, FT-IR, SEM, DSC, BET, XRD and DPPH methods. Lyophilized saponin shown spherical shape and semi-crystalline structure with particle size, polydispersity index, zeta potential, melting point and specific surface area of 7 nm, 0.341, - 15.3 mV, 123.7 °C and 72.14 m² g^-1, respectively. Current research provided a basis for study on further application of lyophilized saponin and development of food emulsions.