| High temperature drying, such as roasting and baking, is a major process in the food industry. Controlling food attributes such as moisture content, color, flavor, texture, thickness, density and surface breakage and at the same time minimizing operating costs is an essential requirement in the design and operation of such processes. But in the past only an empirical approach to process optimization and control was possible. The mathematical tools are now becoming available to treat high temperature drying processes in a rigorous and quantitative way.;A general yet realistic mathematical model has been developed to represent heat and moisture transfer with associated chemical reactions in food material during a high temperature dry cooking process. This model has been used to investigate the effect of several physical and chemical parameters, processing conditions and food material properties on the food product attributes. Both single-layer and multi-layer models have been developed and used.;A controllability study based on linearization has been done on the mathematical model in order to determine whether the dry cooking system can be driven to an arbitrary final state by properly selecting a control variable profile. Several optimization methods have been used in conjunction with the mathematical model to study optimal control of food attributes during the dry cooking of food materials. The optimization problem is treated as a minimum time problem, which may be one of the most important results in practice since it is very closely related with maximum productivity. |
