Effect of Certain Salts on Precipitation of Casein by Calcium Chloride and Heat

Abstract

The effect of sodium chloride, citrate, and phosphate on the precipitation of casein by calcium chloride and heat, and the reversal of the precipitation at lower temperature, has been investigated. The re-solution of the casein precipitate occurs in the presence of sodium chloride and citrate but not in the presence of phosphate. With excess of citrate or phosphate, the precipitation of casein by calcium chloride and heat is prevented; with sodium chloride, a large reduction in the amount of precipitate occurs. Both citrate and phosphate act by binding calcium, a reaction that in the case of phosphate leads to the formation of insoluble calcium phosphate. Sodium phosphate is more effective in preventing casein precipitation by calcium chloride and heat at pH 6.6 than at pH 6.1, because more calcium phosphate is precipitated at the higher pH. © 1957, American Dairy Science Association. All rights reserved.