Influence of pH and calcium concentration on milk protein fractionation by 0.1 μm microfiltration at low temperatures

Abstract

During the microfiltration of skim milk at low temperatures, such as 10–20 °C, the casein micelle partially disintegrates, mainly releasing β-casein into the serum phase, which can pass the membrane along with the whey proteins. This results in undesirable casein losses on the retentate side and in a reduced purity of the whey protein fraction. The goal of this study was to assess means to reduce the permeation of casein monomers during milk protein fractionation by microfiltration at temperatures between 10 and 20 °C. Therefore, calcium concentration and pH variation were applied in order to counter the effect of release of casein monomers. It could be shown that the permeation of serum casein monomers can thus be substantially reduced, without negative effects on flux, as long as the added calcium level does not exceed 5 mm. Whey protein concentration in the permeate remained unaffected up to 1 mm added calcium.