Patent ID: 7378114

Claim:
A method for producing a soluble composition containing isoflavones, comprising: performing a water extraction to obtain a soybean extract liquid from soybean hypocotyls; treating the soybean extract liquid with a protease preparation having a low β-glucosidase activity so as to reduce the formation of aglycone which is formed by breaking a β-glucoside bond between an aglycone moiety and a saccharide moiety of isoflavone glucoside; adjusting the pH value of the soybean extract liquid so that the pH is ≧2 and <5.5 and adjusting the temperature to 0-17° C. after the soybean extract liquid is treated with the protease preparation and removing insoluble materials that are generated after the pH value and the temperature of the soybean extract liquid are adjusted from the soybean extract liquid.