Valorization of Soy Whey Wastewater: How Epigallocatechin-3-gallate Regulates Protein Precipitation

The manufacture of soy-based foods generates significant wastes in the form of soy whey wastewater (SWW). There is a demand for the valorization of SWW due to its high protein content. For this purpose, this study aims at developing a sustainable and environmentally friendly strategy in the recovery of soy proteins from SWW through precipitation proteins using epigallocatechin-3-gallate (EGCG). The precipitation process was optimized with respect to the sample pH and amount of EGCG used, and protein–EGCG aggregates were characterized to obtain insights on their structural and morphological properties. EGCG regulates proteins in SWW to form protein–EGCG aggregates with a 3D hard-sphere configuration. Also, the formed protein–EGCG aggregates have a much greater molecular weight and size than their protein precursor. This interesting phenomenon was depicted as the assembly of protein "snowball" subunits into larger protein–EGCG aggregates. Results from the present study showed that a high protein recovery of 60.7% with a protein purity of 69.51% was obtained, with the recovered protein–EGCG aggregates showing enhanced antiapoptotic properties. In light of this, EGCG could serve as an environmentally friendly approach in recovering proteins from SWW, with the added additional functional properties to the protein–EGCG aggregates.