Microfiltration of milk II: influence of the concentration factor on the composition of Emmental cheese milk and the kappa-casein macropeptide content of the whey

Kappa-casein macropeptide (CMP) is released into whey from K-casein by the action of chymosin during renneting of cheese milk. The content of CMP is 20 to 25% of total whey proteins. When milk is microfiltrated, the permeate contains only the inherent serum proteins. Without CMP, the protein content of total solids in the permeate was ca. 10%, whereas with CMP the content was 13.2%. The permeability of alpha-LA was higher than beta-LG. Since the formation of CMP is dependent only on the casein concentration, it is possible to obtain CMP enriched whey using whey protein depleted MF retentate in cheese manufacture. The concentration factor (CF) had a significant effect on the CMP content of the whey, but the CMP to total protein ratio could be elevated only to ca. 30% with CIF 4, and to ca. 40% at CF 10.5 using diafiltration. CF had limited effect on the action of chymosin and the transfer rate of CMP from milk to whey.