Characterisation of soybean glycinin and β-conglycinin fractionated by using MgCl2 instead of CaCl2

P>A simple two step precipitation method was used to investigate the effect of MgCl2 instead of CaCl2 on fractionation of soybean glycinin and beta-conglycinin. Compositional and physicochemical properties of the resulting protein fractions were characterised. The optimised procedure, in terms of protein yield, purity, phytate content and physicochemical properties, was obtained when the addition of 5 mm MgCl2 was used. After application of 5 mm MgCl2, the phytate content of the glycinin-rich and beta-conglycinin-rich fractions was about 0.4% and 1.3%, respectively, but the addition of 5 mm CaCl2 increased the phytate content of the glycinin-rich fraction to 1.25% and decreased that of beta-conglycinin-rich fraction to 0.67%. Low phytate protein product was suitable for use in infant formula and acidic food. The solubility of the glycinin-rich fractions with MgCl2 was significantly higher than that with CaCl2 at pH < 4.5. Application of MgCl2 improved thermal stability of the beta-conglycinin-rich fraction.