The isolation of whey soy proteins (WSP) from isoflavones in the concentrated solution using foam fractionation was studied, where the concentrated solution was the foamate of foam fractionation. It has been indicated that isoflavones existed in the form of complex with WSP in the foamate. The result of batch dissociation experiments showed that isoflavones were dissociated from WSP through adjusting temperature and pH. Foam fractionation was performed by using the foamate as the feeding solution under the conditions of temperature 50 degrees C, pH 10.0, volumetric air flow rate 40 mL/min and loading liquid height 400 mm. The enrichment ratio and the recovery percentage of WSP reached 9.24 and 89.43%, respectively. The retention percentage of isoflavones in the residual solution was 90.02%. A two-stage batch foam fractionation was developed for successively achieving the enrichment of isoflavones from the soy whey wastewater using WSP as the collectors and the isolation of WSP from isoflavones. (C) 2015 Elsevier B.V. All rights reserved.