The buffering capacity beta of skim milk, of microfiltration concentrates made thereof, and of an evaporated concentrate was analyzed using a titrimetric method and the well-known van Slyke equation. The contribution of the different active buffer pairs was calculated based on their apparent dissociation constants (pKa) and their individual buffering curves. b was found to be correlated with their casein contents, and also with their whey protein-and ash content. Higher concentrations of dry matter, e. g., due to microfiltration or evaporation, result in a higher measured buffering capacity.