Large-scale isolation of food-grade β-casein

Casein fractionation by means of selective precipitation was transferred to small technical scale. The effect of separation using mesh filter bags and small technical separators on the purity, yield, and recovery of beta-casein and additionally on alpha(S)- and kappa-casein was evaluated. By applying small-scale separation, a beta-casein purity of 90 %, a yield of 10 %, and a corresponding recovery of 22 % were achieved, starting with a process volume of 5 L. Separation with mesh filter bags was less suitable, resulting in a considerably lower beta-casein purity and yield. For alpha(S)-casein, only a marginal increase in purity was reached after selective precipitation. Almost threefold kappa-casein enrichment was achieved, whereas the separation method and process scale had no impact on kappa-casein purity, yield or recovery. A further scale-up of the fractionation process using separation to a process starting volume of 85 L resulted in a decrease in purity of the beta-casein fraction to 85 % at comparable yield and recovery. It is suggested that after optimisation of the cold separation step, e.g. by a more effective temperature control, the objective of 90 % purity in the beta-casein fraction may be achieved.