ABSTRACT
The design of food processes, processing equipment, and processing plants has evolved from an empirical art and industrial practice into an applied engineering and economics area, based on the principles and practices of modern Chemical Engineering. Chemical process and plant design have contributed greatly to the development of efficient chemical and petrochemical plants, producing large quantities of industrial (commodity) and consumer products at relatively low cost. The conventional design of chemical processes, equipment, and plants is described in standard books, such as Seider et al. (1999), Turton et al. (1998), Biegler et al. (1997), Perry and Green (1997), Sinnott (1996), Smith (1995), Peters et al. (2003), Douglas (1988), and Walas (1987). The design and operation of the chemical process industries has been improved by the application of modern molecular thermodynamics, mathematical modeling and simulation, and computer technology. These industries process mainly gases and liquids, for which sufficient data and predictive models of their physical and engineering properties are available in the literature (Biegler et al., 1997). Most large chemical process industries are operated continuously, which makes them easier to model, simulate, and control. Limited literature and fewer data are available for food process and plant design. Food products are more sensitive to processing and storage than chemicals, and there are strict requirements on food safety and quality, which should be considered in addition to conventional engineering and economics. The application of Chemical Engineering analysis to Food Process Design has been successful in the classical unit operations of heat and mass trans-
fer (heating/cooling, evaporation, drying, extraction), and in the kinetics of biochemical and microbiological reactions (Fryer et al., 1997; Maroulis and Saravacos, 2003). However, widely used mechanical processing operations of Food Manufacturing, such as size reduction, mechanical separations, mixing and forming, and packaging are still designed empirically, based on industrial experience and technical information from suppliers of equipment (Saravacos and Kostaropoulos, 2002; Walas, 1988; Perry and Green, 1997). Recent research and publications on engineering properties of foods (Rahman, 1995; Rao et al., 2005) and food transport properties (Saravacos and Maroulis, 2001) have improved significantly the quantitative design of food processes and processing equipment. Food Plant Design involves the estimation of capital (investment) and operating costs. The capital cost is based on the estimation of the equipment cost, while the operating cost includes the costs of raw materials, labor, utilities operation, and various overhead expenses. Design and overall cost data of several food processing plants were published by Bartholomai (1987). In addition to conventional Process Engineering, the food plants must comply with the special requirements of hygienic (sanitary) design of equipment and plant facilities, and the safety and quality of the processed food products (Clark, 1997; Clark, 2000; Lelieveld et al., 2003). More attention is paid recently to Food Product Engineering, i.e. the design and engineering of food structure and quality of processed foods. A similar trend is observed in chemical product design (Cussler, 2001). The microstructure of complex fluid and solid food products, such as colloids, emulsions, porous and extruded products, plays an important role in determining their quality and acceptability (Aguilera and Stanley, 1999). The transport properties of foods, especially the mass diffusivity and the thermal conductivity, are affected strongly by the micro-structure (1 – 10 μm) and the macro-structure (0.1 – 10 mm) of the foods (Saravacos and Maroulis, 2001). Food Process Economics is applied to estimate the profitability of food processing operations. The methods used in Process Engineering Economics (Couper, 2003) can be applied to the economic analysis of food processes and processing plants.
