Foam fractionation has the potential to be a significant cost-effective component of a protein concentration and isolation process. Because this process has been regarded primarily as a means to remove water from dilute protein solution mixtures, it has seen little application to the separation and recovery of complex protein mixtures from such systems as those found in seed extracts. In this study, we explore the feasibility of applying foam fractionation to mimosa seed proteins in a water solution. In particular, the effect of pH on the protein recovery and concentration is explored at a constant air flow rate to determine whether the seeds from a plant such as mimosa can be processed with water to fractionate proteins from the remaining polysaccharides (such as starch and galactomannan), fats/oils, vitamins, and nucleotides. From the stationary points of the measured surface tension-pH profile, particular pH's are identified for subsequent process experiments to maximize the separation of the total protein from the solution to the foam phase. These pH's were among those studied to determine the best operating conditions. Eight apparently new proteins (five in significant concentration) were identified in the seeds by their molecular weight, and they were also observed in the foam phase. At pH 9, the enrichment ratio in the foam phase for the total protein mixture was found to be relatively insensitive to the feed protein concentration above 100 mg/L. The enrichment ratio rose from 1.11 at a feed protein concentration of 100 mg/L to 2.46 at 50 mg/L, while the mass recovery fell from 9.9 to 3.7%, respectively.