Chromatographic quantification of isoflavone content from soy derivates using HPLC technique

Glycine max soybean and its derivates stand out as functional food due to its content being free of aglycon isoflavones and their respective beta-glucosides. This study is aimed at classifying and quantifying the isoflavones content in defatted soy flour (DSF) derivates and textured soy protein (TSP). From DSF and TSP samples found in the market, the soy protein isolates (SPI) and the soluble soy protein concentrate (SSPC) were obtained. The isoflavones were extracted from SPI and from SSPC, classified, and quantified through HPLC. The isoflavones daidzein and genistein and their glucosides daidzin, genistin, were found. For the SPI obtained from the TSP, values of beta-glucosides came out with an average of 32.08 mg/100 g. However, for the SPI obtained from the DSF, values averaged 13.32 +/- 0.172 mg/100 g. The highest content levels were observed in the derivates obtained from TSP. SPI was found with the lowest levels of daidzin in SSPC obtained from the DSF. Genistein was only observed in the supernatant, a derivate of SSPC obtained from TSP. During the derivatization process, losses of up to 35.7% of isoflavones in the precipitate occurred. Both SPI and SSPC, obtained from DSF and from TSP, presented great concentration of b-glucosides compounds.