FOULING ON PLATE-TYPE HEAT-EXCHANGERS USED FOR HEAT STERILIZATION OF FOODS

With the recent diversification of foods, various liquid foods are increasingly being sterilized by plate-type heat exchangers. However, the heat from plate-type heat exchangers often causes the liquid foods to adhere to the heated surfaces due to heat denaturation. This results in fouling of the surface of the plates, which affects their operations and causes serious technical problems. Therefore, the authors investigated the heating of various types of liquid foods by plate-type heat exchangers as a basic study of long-run, continuous heat sterilizing processing. In this research, the experiments involved measurement of quantitative food deposits which adhered to the heating surface, composition analyses and physical properties as well as investigations of the influence of the flow rate. Milk was used particularly as a representative sample to make a comparison with other foods. From this, the conclusion indicates an index of flow rate selection to minimize the deposits, and its influence on the overall coefficient of heat transfer and pressure drop.