An optimized version of the UC method as previously described (10,11,35,39,40,45) was used. Human and G1 bovine milk samples were centrifuged twice at 3,000 x g for 10 min at RT to remove the upper cream layer. The supernatants were centrifuged twice at 1,200 x g for 10 min at 4 °C, followed by two top-speed centrifugations at 21,500 x g for 30 min at 4 °C and a final centrifugation at 21,500 x g for 1 h at 4 °C to remove fat globules and casein proteins. The supernatants were filtered through 0.45 μM and 0.22 μM PES syringe filters to remove cell debris and residual fat cells. G2 bovine samples were centrifuged twice at 1,200 x g for 10 min at 4 °C, followed by two top-speed, centrifugations at 21,500 x g for 30 min at 4 °C and a final centrifugation at 21,500 x g for 1 h at 4 °C to remove casein proteins.