Optimization of Subcritical Water Parameters in Protein Extraction from Wheat Germ for Turbidity Removal

Wheat germ (WG) is an excellent source of plant-based protein, suitable as a natural coagulant. This study aims to assess the feasibility of subcritical water (SubCW) as a technique for extracting protein from WG for use in the coagulation process to remove turbidity. SubCW is a non-conventional method that has grown rapidly, driving demand for greener and more efficient extraction. It offers a great advantage, as it uses only water as the solvent for extracting and hydrolyzing bioactive compounds from natural matrices. The optimized extraction of protein from wheat germ for turbidity removal is achieved through response surface methodology. The optimum protein extraction of 22.93 g Protein/100 g WG, which corresponds to 83% of protein being extracted from wheat germ, was obtained at 160 °C and 0.04 g/mL solid-to-water ratio (swr) in 10 min. The kaolin coagulation jar test using the extracts reduced the turbidity by 98.9%. In conclusion, SubCW was able to efficiently extract the protein containing the active coagulant components from WG. It is therefore a promising method for extracting natural coagulant from WG for a green alternative to treat wastewater in treatment facilities.