Changes of Isoflavones During Processing of Soy Protein Isolate

Soy isotlavones have been shown to have anti-cancer and anti-atherosclerosis properties. Soy foods and foods containing soy protein ingredients have great potential in the prevention of cardiovascular diseases and cancers. The objectives of this study were: (I) to investigate the mass balance of different isoflavones during manufacturing of soy protein isolate; and (2) to study effects of processing conditions (washing times and pH) on the retention of isoflavones. The study revealed that only about 26% of the total isoflavories in soy flour remained in soy protein isolate. The isoflavone profile of the soy protein isolate was very different from that of soy flour. The former had much more aglycones (genistein and daidzein), while the latter had almost none. Solid waste and wash water caused the most severe isoflavone loss. Different washing times and different pH value had no significant effect on isoflavone remaining in soy protein isolates