The relationship between the denaturation of β‐lactoglobulin (β‐lg) and the deposition of milk constituents in a heat exchanger was investigated. Experiments were carried out on a plate heat exchanger with skim milk by applying different temperature‐time combinations in the temperature range 70 to 122°C. The aggregation of β‐lg was measured by high performance gel permeation chromatography, and the amount of deposits on the plates of the heat exchanger was determined by chemical oxygen demand measurements. Based on the results of the experiments, a fouling model at temperatures up to 100°C is proposed and some measures to reduce the amount of deposits by more than 5