Preparation of high content soyasaponins by column chromatography and crystallization

In order to obtain high content soyasaponins, Six macroporous adsorption resins including AB-8, XAD-2, HPD-100, ADS-7, HPD-300, and HPD-600 were used to separate soyasaponins by column chromatography. The loading amount, elution rate and purity of soyasaponins had been examined to get the best-suited resin and optimal processing conditions. Then, soyasaponins were further purified by crystallization in ethanol solution. The nature of solvent, initial concentration of soyasoponins and rate of temperature fall were investigated and optimized. The results showed that ADS-7 was the best resin for column chromatography, the optimal operation conditions were as follows: temperature of feed and elution 60℃, feed concentration 6 mg/mL and flowrate of feed and elution 1.0 BV/h. The suitable crystallization conditions were as follows: solvent 30%～40% ethanol, initial concentration 165 mg/mL and rate of temperature fall 3.2℃/h. Under these conditions, the content of soyasaponins could be increased from 3.0% to 45% by column chromatography. The recovery rate was more than 90%. The content could further be raised to more than 96% by crystallization, with a recovery rate of more than 50%. It was indicated that the technology for high content soyasaponins preparation developed in this article was more suitable for industrial production than traditional solvent extraction process.