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Facoltā di Scienze Agrarie e Alimentari Universitā degli Studi di Milano
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Unit operations in food engineering
Code: G290B-
Teacher:  Gabriella Giovanelli
CFU subdivision: Lectures: 7
Practices in classroom: 1
Basic aims:  Knowledge of the phenomena, material balances, energy balances and kinetics of the unit operations of food processing. Knowledge of the basic engineering principles of unit operations and of the mathematical models for the solution of numerical problems of project and control of operations. Knowledge of the schemes, operating conditions and optimization criteria of the most important equipments.
Acquired skills:  Resolution of numerical problems for the engineering and the control of the treatments. Evaluation of the suitability of the equipments and the processing conditions used in the various operations; process optimization. Use of proper technical terminology.
Course contents:  Dimensions and units. Mass balances. Fluid statics and fluid dynamics. Fluid flow, viscosity and rheology. Heat transfer theory: heat conduction and convection. Evaporation. Pasteurization and thermal sterilization. Air-drying and freeze-drying. Sedimentation and centrifugal separation. Filtration and membrane separation. Solid-liquid extraction. For the unit operations described, resolution of heat and mass balances and kinetic equations, description of the equipment and of the optimization criteria.
Program:  P-hysical and thermodynamic properties related to unit operations in food processes, material and energy balances. -Study of fluid statics and fluid dynamics: fluid pressure, Bernoulli's equation, manometers, fluid flow meters, pumps. -Rheology; Newton's equation and power law; rheometers. -Heat transfer by conduction and convection; energy balance in cooling and heating operations; properties of saturated steam; heat exchangers; resolution of problems. P-asteurization and sterilization; death rate of microorganisms (I and II Bigelow's laws); kinetics of heat damage reactions (zero, fisrst and second order); evaluation of kinetic parameters; evaluation of the sterilization effect of thermal treatmens; optimization of thermal treatments; sterilizers and pasteurizers; resolution of problems. -Equilibrium moisture content and water activity. -Air drying: psychrometry; adiabatic saturation of air; Mollier's psychrometric diagram; heat and material balances in air drying; dryers; solution of problems; freeze-drying. -Sedimentation and centrifugal separation; centrifuges. -Filtration: mechanisms of solid retention; filtering materials and aids; filters. -Membrane separations (ultrafiltratin, reverse osmosis). -Solid-liquid extraction:single and multistage concurrent extraction, contiuonous countercurrent extraction; extractors.
Prerequisites:  Students must be familiar with physical properties and fundamental physical and mechanical laws related to the unit operations considered in the course.
Preparatory instructions:  The following propedeutical courses are highly recommended: mathematics, physics and applied physics.
Learning materials:  Textbook: C. Pompei - Operazioni unitarie delle tecnologie alimentari, Casa Editrice Ambrosiana. Some material will be provided by the teacher
Other info:  The final exam consists in a written test, which includes resolution of numerical problems and answers to open questions, regarding phenomenology, plants and optimization criteria of the unit operations discussed in the course.
Program of Unit operations in food engineering (pdf version)
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