Isoflavones are the major phenolics in the soy whey, thus the isoflavone components of the soy whey extracts were analyzed by HPLC analysis. For HPLC analysis, the freeze-dried extracts was dissolved in ethanol (80%) and filtered with a syringe filter (0.45 m PVDF membrane, Bedford, MA, USA), then subjected to HPLC for the qualitative and quantitative analysis of specific isoflavones.The performed HPLC system referred to our previous study reported (Xiao et al., 2014). The mobile phase consisted of deionized water as solvent A (contain 0.1% trifluoroacetic acid) and acetonitrile as solvent B. The temperature of the column oven was set at 25 °C. The solvent flow rate was 0.8 ml/min, using a gradient of 10% B (90% A) at 0 min, and then increased to 25% B in 10 min. Solvent B sequentially increased to 30% in 2 min and then ramped to 55% in 13 min. Finally, it decreased to 10% B over 5 min. An autoinjector was used to inject 20 l of the test solution into the HPLC system. The wavelength used to monitor was set at 254 nm. Results were expressed as mg/g of extract.