Effect of pH Shifting on Different Properties of Microwave-Extracted Soybean Meal Protein Isolate

Extraction and improvement of plant-based protein isolate by microwave and pH shifting treatment have received increasing attention to widening its applications. In the current study, protein isolate was prepared by optimizing microwave treatment parameters from soybean meal, and the impact of pH shifting on the microwave-extracted soybean meal protein isolate (SMPI) was analyzed. The maximum yield and purity were obtained at the optimal microwave treatment conditions of 16:1 v/w, 600 W, and 32 s of liquid-solid ratio, power, and time respectively. The SMPI samples shifted at various pH after microwave treatment showed better functional characteristics like solubility, emulsion forming capacity, wettability, and foaming capacity and stability than the control sample (non-pH shifted). The structural characteristics of pH-shifted SMPI studied through FTRI and XRD indicated the presence of more ?-sheets, increased hydrogen bonds, and less crystalline conformation than the control sample. The SMPI sample shifted near the isoelectric point of protein showed better thermal properties than other pH-shifted samples. This study demonstrated that pH shifting of SMPI extracted by microwave treatment causes desirable changes and can play a huge role in the utilization of soybean meal for food product development.