Protein recovery and anti-nutritional factor removal from soybean wastewater by complexing with a high concentration of polysaccharides in a novel quick-shearing system

In this study, to recover proteins and minimize anti-nutritional factor (ANF) levels in soybean wastewater, a novel quick-shearing system was used to obtain homogeneous electrostatic complexes between soybean whey protein (SWP) and a high concentration (4%, w/v) of polysaccharide. During processing, protein recovery and trypsin inhibitory activity loss induced by complexing with sulfated and carboxylated polysaccharides were investigated as function of polysaccharide type, pH, protein to polysaccharide mass ratio, and the physical state (solid, liquid). The removal of 80% of ANF levels and recovery of 90% of proteins were achieved using solid sulfated polysaccharides. Large amounts of particle complexes were observed for sulfated polysaccharides as compared to carboxylated polysaccharides by confocal laser scanning microscopy. A 100-kDa polyethersulfone ultrafiltration membrane was effective in recovering proteins (80%) from ι-carrageenan/SWP complexes, and a small amount of loss of the polysaccharides was observed for each cycle.