The Isolation, Purification And Analysis Of Isoflavones In Defatted Soybean

The dissertation focuses on the research of isoflavones and soyasaponins in soy meals. Soyisoflavones and soyasaponins are two main components of activity and nutrition in soybean, which are in the focus of food and nutritional research nowadays due to their numerous health-promoting properties. Soyisoflavones have bioactive properties of cholesterol lowering, carcinogenesis prevention and alleviation of osteoporosis and menopause syndrome etc. Soyasaponins have beneficial properties of fat and cholesterol lowering, antioxidant activity, cancer prevention and immunity promoting etc.They can be widely used in pharmacy, healthful food and additives.In this dissertation, we mainly studied the extraction, isolation and purification methods of soyisoflavones and soyasaonins from soy meals. Especially the modern analytical methods were developed to measure the contents of the products.1 .The isolated and purified conditions of soybean isoflavones were studied and the best techniques were confirmed as follows: the ethanol extracts were cooled 48 hours and centrified 10 minutes at 3600r/min, the supernatant liquid was decompressed and condensed without ethanol odor, then refrigerated 24 hours and degreased. Following hydrochloric acid was added to it until the value of the meal extracts achieved its isoelectric point. After stocked at 4 癈 for 72 h, it was precipited and the supernatant liquid was neutralized. In succession the mixture was passed the macroporous adsorption resin.The impurity such as sugars and salts could be eluted by distilled water from the macroporous adsorption resin column and the isoflavones could be eluted by 30%, 60%, 95% ethanol. On the other hand, the isoflavones also could be eluted directly by 95% ethanol. The eluates were decompressed and condensed to produce the rude products I.2.The several adsorption method and solvent precipition method were studied in concentrating soyisoflavones and soyasaponins from the meal extracts, and the two methods were compared. The resulting analytical data showed that the silica gel column was eluted by chloroform-methanol-water (65:35:10,v:v:v), the purity of soyisoflavones and soyasaponins purified by the silica gel exceed 90% respectively. The polyamide column was gradient eluted by methanol and athyl acetate, the soyisoflavones and soyasaponins were separated preferably.The Sephadex LH-20 column was eluted by 50% methanol, the soyisoflavones and soyasaponins are baseline separated.3.The capillary eletrophoretic seperation of the three standard samples genistein, genistin and puerarin were investigated. The effects of the concentration and pH value of buffer solution on the separation behavior of the above three standard samples were also discussed. The best seperation condition of them was founded. Under the proposed CE method, the contents of genisteuu daidzin and genistin were detected in some extracts of isoflavones.4.We optimized the ionization conditions of the three isoflavones separately. In the same time, HPLC/ESI/MS was employed to study the isoflavone products II .The components were identified by standards, and ESI/MS and the contents of the isoflavones were determined by peak areas. The results obtained by HPLC were similar to those by HPCE.