Process steps for the preparation of purified fractions of alpha-lactalbumin and beta-lactoglobulin from whey protein concentrates.

Fractions enriched with alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-lg) were produced by a process comprising the following successive steps: clarification-defatting of whey protein concentrate, precipitation of alpha-lactalbumin, separation of soluble beta-lactoglobulin, washing the precipitate, solubilization of the precipitate, concentration and purification of alpha-la. The present study evaluated the performance of the process, firstly on a laboratory scale with acid whey and then on a pilot scale with Gouda cheese whey. In both cases soluble beta-lg was separated from the precipitate using diafiltration or microfiltration and the purities of alpha-la and beta-lg were in the range 52-83 and 85-94% respectively. The purity of the beta-lg fraction was higher using acid whey, which does not contain caseinomacropeptide, than using sweet whey. With the pilot scale plant, the recoveries (6% for alpha-la; 51% for beta-lg) were disappointing, but ways of improving each step in the process are discussed.