Dissolution behavior of soy proteins and effect of initial concentration.

The solution concentration profiles of soy protein and its components, glycinin and beta-conglycinin, as a function of pH and initial concentration have been measured. The concentration profiles generally followed a U-shaped trend with pH, with a minimum at around pH 4-5. Dissolution concentration unexpectedly increased with the initial concentration of the solution, with the increase being approximately proportional to the increase in initial concentration. The reasons for this are not clear. For the initial concentrations studied, beta-conglycinin is undersaturated between pH 5 and 7 and remains in solution, while glycinin becomes supersaturated in the same pH range and precipitates. Therefore separation of the two proteins can be achieved.