Characterization of the Nonvolatile Minor Constituents Responsible for the Objectionable Taste of Defatted Soybean Flour

A scheme was developed for the separation of the nonvolatile minor constituents from soy flour which are responsible for the astringent an bitter tastes. The scheme involved solvent extraction, freeze drying, and fractional crystallization. Two fractions, collected by semipreparative HPLC, had the characteristic bitter and astringent tastes. Further fractionation by reverse phase HPLC produced three pure compounds which were identified by UV, NMR spectrometry and elemental analysis, as daidzein, glycitein 7‐β‐O glucoside, and genestin. Preliminary sensory evaluation showed that these isoflavones might contribute additively to the undesirable bitter and astringent tastes of soy protein products.