Active Substances And Product Development In Germinated Soybean By Pressurized Solvent Extraction

It is well-known that soybean contain rich nutrients, such as free amino acids, isoflavones,soluble protein and gamma-aminobutyric acid (GABA), etc. In germinating soybean, the total freeamino acids, isoflavones, soluble protein and GABA have a large improvement compared withthose of dried soybean. However, the total sugar, crude fat, fat oxidase, phytic acid, trypsininhibitor in germinating soybean decrease. In this dissertation, we studied1) the changing ofchemical composition of soybean during the period of germination;2) active substances fromblack bean and germinated soybean by accelerated solvent extraction method;3) in developing aseries of soy milk products. At present, there has been a patent named "soy milk made fromgerminated soy beans" in USA. However, there is no research report and products aboutgerminated soy in our country. So, the research will provide foundation and theoretical supportsfor the deep processing of domestic soy products. Meanwhile, it will have profound significance todevelop soy products containing active substances.Firstly, we studied the changing amounts of different nutrients in the germinated soybeans.The results: total reducing sugar increased by50.9%after12h germination; the soluble protein washigher than dry soybeans during the germinating periods, and the peak appeared in the soaksoybeans at12h and in the germinating soybeans at24h; the nitrogen solubility index was themaximum in the soak soybeans at12h and in the germinating soybeans at36h and increased by66%and59%, respectively; the content of glutamic acid, free ammonia nitrogen, GABA andsoybean isoflavones also increased by14.3%,41.8%,44.5%and38.9%respectively. The results ofliquid chromatography confirmed that the glycoside form of soybean isoflavones can be convertedinto aglycone form in the germinating soybeans, and daidzin aglycone content increased by0.0819%and genistein content increased by0.0553%. Besides, crude fat reduced by23.8%after48h germination, and phytic acid and trypsin inhibitor decreased by14.4%and12.9%at24h,respectively. Moreover, fat oxidase activity also showed a trend of decrease during the germinatingperiods.Fourthly, technical methods of GABA extracted in the germinated soybeans with acceleratedsolvent extraction were studied. According to orthogonal test, the optimized extraction conditionof GABA were: the extracting temperature was125℃,7min of the extracting time,0.8kPa ofextracting press and75mL/g of the liquid-solid ratio. Under this condition, the maximum yield ofGABA extracted was31.66mg/g.Secondly, we studied technical methods of total isoflavones in black beans using acceleratedsolvent extraction. According to orthogonal tes, the optimized conditions of total isoflavonesextraction were: the extracting temperature at110℃,75%of ethanol concentration,15min ofextracting time,700kPa of extracting press and30mL/g of the liquid-solid ratio. Under this condition, the maximum yield of the total isoflavones extracted in black beans was1.43%, thecrude yield of isoflavone extraction was12.58%and the purity of isoflavone was3.76%. After thetotal isoflavones were puritied by macroporous resin, the purity of isoflavone was25.67%.Thirdly, the separation of isoflavones in black beans was studied by high-speedcounter-current chromatography (HSCCC). The optimized solvent system was that the ratio ofethyl acetate, acetic acid and water was5:1:10. By the separation and HPLC qualitative analysisfor each fraction, the high purity isoflavones was obtained and the purity was85.54%.At last, a series of soy milk products with high content of active substances were developed.The soybean cultivar containing high isoflavone, genistein, daidzin aglycone, protein and low fatwas selected from129kinds of soybeans. Furthermore, soy milk with high content of activesubstances was produced according to alteration rule of active substances during the germinatingperiod of soybeans. For example, using soybean of resistance to line5and germinating for24h, thesoy milk with high isoflavone and GABA was made. In addition, using fat gsh-px activity as anindex, we determined the optimum deodorization method:6min of the microwave time,microwave temperature at75℃and60ml/g of material quantity. Under this condition, fattyoxidase activity was the lowest. The optimum processing of soy milk products was:8min of themicrowave time, as4times much as water, three times of grind and0.4%of NaHCO3.