Modelling techniques for the control of thermal exchanges in mixed continuous–discontinuous flow food plants

In food processing plants chemical, microbiological and organoleptic properties of products modify according to kinetics that typically depend on the time–temperature (tT) profile assumed by the product during the process. The knowledge of these profiles could be profitably used to control the process in order to enhance the product quality. This paper presents a modelling framework, based on the use of compartmental models, to determine the tT-profiles of food products processed in mixed continuous–discontinuous flow conditions as in the case, for example, of plants presenting accumulation points, like tanks, kettles or vats, as well as valves and pumps that are suitably switched on and off. This approach allows the derivation of the tT-profile of any portion of the food product with a limited computational effort. Together with the analytic description of the modelling structure and of its elements, the paper presents a case study concerning a stage of a peach juice production plant to show the effectiveness of the proposed approach.