Method for producing composition containing soluble isoflavones

Abstract

A method for producing a composition containing soluble isoflavones is described, which uses soybean materials as raw materials. The composition is obtained in a natural state without addition of solubilizing agents and chemical modification, and has high solubility under neutral to acidic conditions and good long-term stability under refrigeration. By removing the insoluble materials from the water-extract liquid of a soybean material having a pH value of 2-7 and a temperature of 0-17° C., a composition containing isoflavones can be efficiently obtained with high solubility under neutral to acidic conditions and good stability under refrigeration.

What is claimed is:  
     
         1 . A method for producing a composition containing soluble isoflavones, comprising: 
 preparing a soybean extract liquid that has a pH value adjusted to 2-7 and a temperature adjusted to 0-17° C.; and    removing insoluble materials from the soybean extract liquid.    
     
     
         2 . The method of  claim 1 , wherein an amount of isoflavones is 0.2-20 wt %, a crude protein content is 30 wt % or less, and a lipid content is 4 wt % or less in total solid content of the soybean extract liquid.  
     
     
         3 . The method of  claim 1 , wherein preparing the soybean extract liquid comprises a process of adjusting the pH value of the soybean extract liquid to 5.5-7 without a protease treatment.  
     
     
         4 . The method of  claim 2 , wherein preparing the soybean extract liquid comprises a process of adjusting the pH value of the soybean extract liquid to 5.5-7 without a protease treatment.  
     
     
         5 . The method of  claim 1 , wherein preparing the soybean extract liquid comprises: 
 a process of adjusting the pH value of the soybean extract liquid to satisfy the equation “2≦pH<5.5”; and    a process of treating the soybean extract liquid with a protease.    
     
     
         6 . The method of  claim 2 , wherein preparing the soybean extract liquid comprises: 
 a process of adjusting the pH value of the soybean extract liquid to satisfy the equation “2≦pH<5.5”; and    a process of treating the soybean extract liquid with a protease.