Abstract: Disclosed is a process comprising: mixing a soy protein-containing material with an aqueous medium; removing the non-solubilized solids from the slurry to form an alkaline liquid containing solubilized soy protein; adjusting the pH of the solubilized soy protein liquid to between about 3.8 and about 6.6, to precipitate soy protein from the liquid; separating the precipitated soy protein from the pH-adjusted soy protein liquid; resolubilizing the separated soy protein precipitate in an aqueous medium at a pH of from about 1.8 to 3.2; treating the resolubilized soy protein with at least one water-soluble calcium salt to form a calcium-enriched soy protein mixture; precipitating soy protein from the calcium-enriched soy protein mixture by adjusting the pH of the mixture to between about 3.8 and about 6.6; separating the precipitated soy protein from the calcium-enriched soy protein mixture; and washing to form calcium-enriched soy protein isolate having selectively reduced manganese concentrations.