Water Retention and Solubility of Soy Proteins and Corn Germ Proteins in a Model System

Response surface methodology was used to study water retention and protein solubility of soy flour (SF), concentrate (SC), and isolate (SI), and corn germ protein flour (CGPF). Water retention increased with pH (6 to 8) and incubation temperature (10–70°C), but not with increasing incubation time (10–30 min). SC had highest water retention per gTam, followed by CGPF, SF, and SI. Water retention in relation to protein content was higher in CGPF than in the three soy products. Protein solubility was significantly affected by pH and temperature of incubation. Protein solubility increased when pH (6 to 8) and incubation temperature increased (30–70°C) in all samples. SI had highest protein solubility, and CGPF had the lowest.