Solubilities of Soybean Saponins and Their Solubilization with a Bisdesmoside Saponin

Abstract

The solubilities of Bb (soyasaponin I), one of the major monodesmoside saponins in soybean seeds, were measured in aqueous ethanol and buffer. Bb showed the highest solubility in 60% ethanol, and was more soluble in alkaline region in buffers prepared at various pHs. On the other hand, Bb'(soyasaponin III) and B-G (3-O-β-D-glucuronopyranosyl soyasapogenol B) were almost insoluble in buffer. Solubilities of Bb, Bb'and B-G in buffer were increased by the addition of Ab (acetyl-soyasaponin A1), which is one of the major bisdesmoside saponins in soybean seed hypocotyl. The solubilizing effects of bisdesmoside saponins on monodesmosides, which are responsible for some physiological effects in soybean, may be important for processing beneficial foods using saponins for human consumpution.