Effect of pasteurization on the distribution of bovine milk transforming growth factor-β2 in casein and whey fractions during micro- and ultrafiltration processes

Whey from bovine milk or colostrum is usually used as a raw material for separation and concentration of small bioactive compounds, such as growth factors. In this work, transforming growth factor-β2 (TGF-β2) was concentrated from farm milk. Casein was separated and concentrated by microfiltration, followed by ultrafiltration of the permeate to concentrate whey proteins. TGF-β2 concentrations were monitored throughout the processes. The distribution of TGF-β2 during microfiltration and ultrafiltration was compared between pasteurized and non-pasteurized milk. For pasteurized milk, 80% of the growth factor was in the casein fraction, in the heat-activated immunoreactive form. For non-pasteurized milk, TGF-β2 was distributed between the casein fraction (55%) and the whey fraction (37%), mostly in the latent form. The highest growth factor concentration was in the ultrafiltration retentate of non-pasteurized milk if expressed per protein content (3.5 μg g−1 protein). The total recovery of TGF-β2 was 83% (pasteurized milk) or 93% (non-pasteurized milk).