CONCEPTION OF A STERILE CONCENTRATION PRO CESS OF MILK BY MULTISTAGE FLASH EVAPORATION

Today sterile milk concentrates, as, e.g. evaporated milk, are produce d in a manner that concentration of milk is done prior to sterilizatio n. This manufacturing process, which is normally applied, if the conce ntrate is sterilized in closed containers and is not feasible otherwis e under non-sterile filling conditions, is also used, if the product i s sterilized continuously according to the UHT-process. To maintain he at stability and shelf life of the concentrate mostly stabilizers are added. With the proposed combined sterilization- and concentration pro cess the milk is first sterilized continuously, e.g. according to the UHT-process. After reaching the desired sterilization temperature the product is concentrated during subsequent cooling. This processing ste p can be carried out using flash evaporation; here not only water evap oration, but also cooling of the concentrate takes place. Multistage f lash evaporation and additional utilization of the vaporizer for evapo ration of the product allow dry matter contents of up to approximately 40 % to be obtained as a function of the number of units. For concent rating the milk during the cooling phase exclusively energy is used wh ich is applied to the product during heating to the desired sterilizat ion temperature. Compared with the traditional manufacturing method th is leads to considerable energy savings, which can, further, be increa sed by use of the vapor condensate during preheating of the cold produ ct. The new method presupposes that cooling associated with concentrat ion is carried out under sterile conditions. This is technically easil y possible by means of flash evaporation. As to the apparatus to be us ed, the plate evaporator would be well suited for this.