Enhancement of separation rate and recovery efficiency of milk whey proteins by addition of calcium and magnesium ions in batch foam separation

Abstract

The influence of Ca2+ and Mg2+ to milk whey solution at pH 6 on the enhancement of proteins recovery in batch foam separation was investigated. The pH of whey solution produced in cheese production was about pH 6. The separation rate was evaluated by the separation rate constant, k, by fitting to first-order kinetic equation, and the recovery efficiency was evaluated by the fraction of residual concentration of whey proteins. In the comparison of the case without and with the addition at pH 6, in the case with the addition of Ca2+ and Mg2+ in the range over 0.06 mol/L, the k became 4.4-fold and 2.0-fold larger, and the recovery efficiency became 5.3-fold and 1.9-fold larger than those in the case without the addition. The overall equilibrium adsorption constant, K, and the overall saturated adsorption density, Xs, were also affected by the addition of Ca2+ and Mg2+. The variation tendency of K and Xs was quite different. As increasing the concentration of both Ca2+ and Mg2+, mostly K decreased, on the other hand, Xs increased. Judging from these results, the formation of aggregates/complexes of whey proteins by the addition of Ca2+ and Mg2+ was suggested. The addition of Ca2+ and Mg2+ could enhance the separation rate and recovery efficiency.