Whole milk was heated in the range 65-95 o C using a pilot-scale UHT plant, and analysed by quantitative polyacrylamide gel electrophoresis. Kinetic and thermodynamic parameters for the association of β-lactoglobulin (β-lg) and α-lactalbumin (α-la) with the milk fat globule membrane (MFGM) were determined. Arrhenius plots showed an abrupt change in temperature dependence of the rate constants at 85 o C for β-lg and 80 o C for α-la. Association of β-lg and α-la with the MFGM was described by first-order reaction (65-85 o C for β-lg and 70-80 o C for α-la) in the low temperature range and a second-order reaction in the high-temperature range (85-95 o C for β-lg and 80-95 o C for α-la). Thermodynamic parameters indicated that the protein denaturation was the rate-determining step in the low temperature range and aggregation processes were rate-determining in the high-temperature range.