Pilot study of recovery of whey soy proteins from soy whey wastewater using batch foam fractionation

• Foam fractionation of whey soy proteins (WSP) was performed at 120 L in volume.
• Effect of each processing procedure on food-related properties of WSP was studied.
• The end product decreased by 40% in the levels of the food-related properties.
• The up-scaling effect in foam fractionation of WSP was analyzed.

For industrializing foam fractionation of whey soy proteins (WSP) from soy whey wastewater, a pilot study of 120 L in liquid loading volume was conducted. Firstly the effects of sodium bisulfite concentration, superficial gas velocity and temperature were investigated for increasing the WSP recovery. Furthermore the protein composition of WSP before and after foam fractionation was analyzed. Then the effects of foam fractionation, thermal sterilization and spray-drying on the fraction of soluble proteins, foaming properties, and emulsifying properties of WSP were examined. Finally the up-scaling effect of foam fractionation was analyzed. The results show that the end product of WSP with an effective recovery of 30.6 ± 1.5% had Kunitz trypsin inhibitor (the major ingredient), lipoxidase, β-amylase and lectin. The processing procedures, particularly foam fractionation and thermal sterilization, resulted in about 40% decrease in the levels of the food-related properties. The up-scaling effect slightly decreased the WSP recovery and intensified their denaturation.