A Doehlert experimental design was conducted and surface response methodology was used to determine
the effect of temperature, contact time and solid liquid ratio on isoflavone extraction from soybean
flour or Soybean Protein Isolate in pressurized water system. The optimal conditions conducted gave an
extraction yield of 85% from soybean flour. For Soybean Protein Isolate compared to soybean flour, the
isoflavone extraction yield is 61%. This difference could be explained by higher aglycon content, while
aglycon appears to be the least extracted isoflavone by pressurized water. The solid liquid ratio in the
ASE cell was the overriding factor in obtaining high yields with both soybean products, while temperature
has less influence. A high temperature causes conversion of the malonyls-glucosides and glucosides
isoflavone derivatives into glucosides or aglycons forms. pressurized water extraction showed a high solubilization
of protein material up to 95% of inserted Soybean Protein Isolate.