Fouling of heat exchangers in the dairy industry

A general overview is given of the main factors in the fouling of processing equipment used for heating dairy fluids. The data collected indicate that the primary step in fouling is the adsorption of a monolayer of proteins onto the wall of the heating equipment at room temperature. Real fouling (i.e., the formation of macroscopic layers of foulants), however, is caused by particle formation in the bulk of the liquid being processed. These particles include both whey protein aggregates and calcium phosphate particles. Their formation is heat induced, and the deposition takes place through diffusion toward the heating surface. Only very high flow rates are able to prevent their deposition and subsequent sticking. To better control the process of fouling, special attention is given to the parameters affecting the formation of both types of particles and how their formation can be retarded or prohibited, including the role of calcium sequestrants, pH, preheating, and flow rate herewith. (C) Elsevier Science Inc., 1997.