The invention relates to a method and a device for reducing the growth of thermophilic bacteria in heat exchangers of dairy processing plants, in which untreated milk or the fractions thereof, cream and skimmed milk (M), that has/have not undergone heating to a high temperature to deactivate thermophilic bacteria is/are subjected in this state to a thermal treatment in a further treatment process in a recuperative heat exchanger, at least in a temperature range of 50°C to 70°C, wherein the optimum temperature (Top) for the optimal growth of the thermophilic bacteria lies in a temperature range of 63°C to 68°C (63°C < Top < 68°C). The method according to the invention and the device for carrying it out ensure an increase in the lifetime of the recuperative heat exchangers that are exposed to untreated milk or the fractions thereof (cream and skimmed milk) and are in particular operated regeneratively. This is achieved by a method in which, before its thermal treatment, which is performed • either in the region of the optimum temperature (Top) • or when passing through the region of the optimum temperature (Top) in one direction or the other, the non-deaerated skimmed milk (M) provided in the treatment process undergoes deaeration and thereby becomes deaerated skimmed milk (M*).
