G.D. Saravacos’s research while affiliated with Rutgers, The State University of New Jersey and other places

Mechanical transport of food materials may be divided into fluid and solids transport. The mechanical transport of air, gases, and vapors is carried out by fans, blowers, compressors, vacuum pumps, and ejectors, which are discussed briefly in Appendix D (Utilities). For the transport of liquids, semifluids, and suspensions, pumps are used. The transport of fluid foods by pumping in process pipelines is a well-developed technology, based on the theory of fluid mechanics, and applied extensively in the chemical process industries ([Perry and Green, 1997]). The mechanical transport equipment is often used in combination with other food processing equipment, such as heating and cooling of water, air, or steam, and fluidization and transport of particles ([Loncin, 1969]).

Size reduction or enlargement of solid foods can be attained by mechanical methods, without use of heat. Size reduction refers to the production of large or small pieces and several particle sizes. Enlargement includes agglomeration or coating of small food pieces or particles. In the case of liquids, size reduction of particles is achieved by homogenization. Below, the sections, “Size Reduction” and “Size Enlargement” deal with solid foods, while “Homogenization” deals with size reduction of liquids.

Refrigeration is applied to cooling/chilling and freezing of foods. The freezing temperature of foods (around 0° is the borderline between the cooling and the freezing processes. In food processing, low temperatures are applied: (1) for preservation and (2) in facilitating other nonpreservation processes or manufacturing products that are directly or indirectly related to foods. In preservation, the main aim is to extend the shelf life of fresh or processed products through cooling, chilling, freezing, and subsequent storage, by reducing the activity of microorganisms, enzymes, and chemical and biological reactions. In preservation, two main categories are distinguished: (1) the application of refrigeration without any other method and (2) the application of refrigeration in connection with some other method of preservation.

A number of novel food processing and preservation methods and equipment have been developed and applied or evaluated for commercial application. They are the result of research and development efforts in food science and technology and in other process technologies. Some of these processes are already applied commercially in the food industry, such as membrane separations and supercritical solvent extraction, while most of the others are still in the development and evaluation stages. Some technical, economic, and public acceptance difficulties must be resolved before there is large-scale application.

The principles of mechanical design and construction of food processing equipment are similar to those for the equipment of the chemical and process industries. The basic engineering requirements of process equipment are the containment of the material, the strength of the components, the efficiency of the operation, and the transfer of energy during processing. The equipment should be resistant to corrosion, be cost-effective, and its operation should not present occupational hazards to the operators. In addition, the food processing equipment must comply with strict standards and regulations, which are necessary for securing the quality and safety of the food products to the consumers.

This text covers the design of food processing equipment based on key unit operations, such as heating, cooling, and drying. In addition, mechanical processing operations such as separations, transport, storage, and packaging of food materials, as well as an introduction to food processes and food processing plants are discussed. Handbook of Food Processing Equipment is an essential reference for food engineers and food technologists working in the food process industries, as well as for designers of process plants. The book also serves as a basic reference for food process engineering students. The chapters cover engineering and economic issues for all important steps in food processing. This research is based on the physical properties of food, the analytical expressions of transport phenomena, and the description of typical equipment used in food processing. Illustrations that explain the structure and operation of industrial food processing equipment are presented. The materials of construction and fabrication of food processing equipment are covered here, as well as the selection of the appropriate equipment for various food processing operations. Mechanical processing equipment such as size reduction, size enlargement, homogenization, and mixing are discussed. Mechanical separations equipment such as filters, centrifuges, presses, and solid s/air systems, plus equipment for industrial food processing such as heat transfer, evaporation, dehydration, refrigeration, freezing, thermal processing, and dehydration, are presented. Equipment for novel food processes such as high pressure processing, are discussed. The appendices include conversion of units, selected thermophysical properties, plant utilities, and an extensive list of manufacturers and suppliers of food equipment.

Size reduction or enlargement of solid foods can be attained by mechanical methods, without use of heat. Size reduction refers to the production of large or small pieces and several particle sizes. Enlargement includes agglomeration or coating of small food pieces or particles. In the case of liquids, size reduction of particles is achieved by homogenization. Below, the sections, “Size Reduction” and “Size Enlargement” deal with solid foods, while “Homogenization” deals with size reduction of liquids.

Packaging of food consists of the operations shown in Fig. 13.1. These operations may be distinguished in package preparing operations, product preparing for filling operations, filling in packages, closing (sealing), control of filled packages, and preparation for storage and shipment. The equipment used in feeding the food into the filling unit depends on the nature and properties of the food. For liquids, pumps or gravity is used. For granulates or small pieces, transfer can be done pneumatically, by special pumps, gravity, or belts. Larger pieces are transferred to the packaging line by conveyors or trucks. Before being packaged, the product is stored shortly in feeding tanks or other containers. Depending on the filling technique, the tank may be open or closed. The product in closed tanks may be under pressure or in vacuum. When using trucks or conveyors, mounted on the ceiling, the short storage may be in intermediate bulk containers (Chap. 3), replacing the fixed short storage equipment. In all cases, the main aim of short storage is to have a product of constant properties. Therefore, if, e.g., a liquid food consists of mixed components, it is continuously agitated to secure homogeneity in consistency and temperature.

Heat transfer equipment is used in most food processing operations as an important part of the manufacturing or preservation processes. The transfer of energy to or from food materials during processing requires special equipment, which is designed and operated on the basis of the engineering principles of heat transfer and the experience and practice of food process engineering.

Food process design is concerned with the engineering design and economics of industrial food processes. Quantitative analysis of food processing operations requires material and energy (heat) balances on the process flowsheet. Equipment and energy (heat) requirements are calculated from rate equations of momentum (flow), heat, and mass transfer. Process engineering calculations require the thermal and transport properties of foods, which are taken from the literature. Reliable values of thermal properties (specific heat and enthalpy changes) can be predicted from empirical correlations or taken from published data. Transport properties (viscosity, thermal conductivity, and mass diffusivity) are strongly affected by the composition and physical structure of the food product, such as apparent density and porosity. The rheological properties of fluid foods are affected by the size and concentration of the dissolved molecules or suspended particles. Temperature has a stronger effect on the viscosity of concentrated solutions, such as sugars, than on the apparent viscosity of suspensions. Experimental data on thermal and mass diffusivity are essential. The thermal conductivity of solids decreases at higher porosities, while the opposite effect is observed with mass diffusivity. Temperature has a small effect on thermal conductivity, while mass diffusivity is affected strongly in nonporous and less in porous solids. Heat and mass transfer coefficients in food process design are affected by the heat transfer medium, food material, and process equipment. Approximate values of the transfer coefficients are obtained from data in the literature and empirical correlations.