Non-reducing 2-DGE of sweet whey fraction from heat-treated milk visualised by colloid Coomassie Brilliant Blue G-250 staining. The sweet whey was prepared from skimmed milk of one representative individual cow and separated in an 8–16% polyacrylamide gel at a pI gradient from 4 to 7. A total of 150 μg of protein was applied. The positions of protein spots referred to in Tables III and IV are indicated by an arrow and by their identification number in the image analysis of the non-reducing gels.