Mechanical Processes in Food Processing Systems Mechanical Processes

Mechanical Processes in Food Processing Systems

Mechanical Processes • Mechanical processing operations are very important in food processing. • They include: – mechanical transport of food materials, – mechanical processing, and – mechanical separations.

– Mechanical transport includes: pumping and mechanical conveyors; – Mechanical processing is concerned with: size reduction, agglomeration, mixing, and forming; – Mechanical separations involve: filtration, centrifugation, and expression.

Mechanical Transport Operations • Liquid and semi-fluid foods are transported in food processing plants using various types of pumps, • Food particles (powders) and grains are transported by pneumatic conveyors. • Hydraulic conveying is used for large food pieces, • Various types of mechanical conveyors are used for solid foods, food packages and containers.

Transport of Fluid Foods • Rheological data are required for the design of pumping of fluid foods in piping systems. (Most fluid foods are non-Newtonian fluids) • Table 2. 3 shows some important fluid transport equipment used in food processing.

Fluid Transport Equipment Pumps Centrifugal Radial, axial flow Positive Displacement Lobe, gear, piston, progressive cavity Applications Low viscosity fluids Dilute suspensions Viscous, sensitive fluids and pastes Pneumatic Conveyors Particles and grains suspended in air Hydraulic Conveyors Fruits and vegetables suspended in water

Mechanical Conveyors Equipment Applications • Belt Conveyors Particles, pieces, packages • Roll Conveyors Packages, heavy products • Screw Conveyors Pastes, grains • Chain Conveyors Containers • Bucket Elevators Particles, grains

• • • Mechanical Processing Operations Equipment Cutting Equipment : Slicers, dicers Grinders : Roll mills, hammer mills disc grinders, pulpers • • Agglomerators – Rotary pan, drum – Fluidized-bed, drying Compression, pelletizing • Homogenizers Milk products • • • Pressure, colloid mills Mixers Agitated tanks mixers of solids Food emulsions • • • Forming/Extrusion Equipment Forming extruders Twin extrusion cookers Applications Fruits / vegetables , meat Cereal grains , fruits / vegetable, meat Food granules from food powders Liquid/liquid, liquid/solid/solid Forming of cereal foods extrusion cooked products

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