93832 - Process innovation in the food industry

Academic Year 2023/2024

  • Docente: Luigi Ragni
  • Credits: 9
  • SSD: AGR/09
  • Language: Italian
  • Teaching Mode: Traditional lectures
  • Campus: Cesena
  • Corso: Second cycle degree programme (LM) in Food Science and Technology (cod. 8531)

Learning outcomes

At the end of the teaching, the student has acquired the knowledge about the innovative solutions applied to food plants, in particular for the thermal treatments, the homogenization and drying and is able to operate some technical choices. At the end of the course the student has acquired the knowledge of the principles of operation, the dimensioning and choice of modern refrigeration systems. The student has also acquired the basic technical, legal and normative concepts on safety of the equipment.

Course contents

Plant schemes

Process and driving schematics: normative and associations references, nomenclature and symbology, main parts, process and service lines, instruments, controls, valves, filters, materials.


Dryers for grain: parameters describing the drying process, heater group, desiccant container, classification of dryers for grain, functional parameters of the dryer, Mollier diagrams. Dryers for food fluids: spray (turbine, nozzle pressure, conventional two-stage dryer, "high," "compact", non conventional dryer, freeze dryer or lyophilizer, roller dryer (single, double rolls), steam tube dryers, rotary vacuum, continuous and discontinuous fluidized bed agglomerators.

Pasteurizers and UHT sterilizers

Parameters of pasteurization, pasteurization plant, UHT plant by direct exchange (plate, tube bundles, scraped body), UHT plant by direct exchange (injection and direct steam infusion), advanced facilities by infusion.

Heat concentrators or evaporators

Traditional bubble concentrators, with rotating coil, submerged tubes in natural or forced circulation, agitated film, vertical tube bundles (falling and rising film, with natural or forced circulation), bubble expansion. Accessories: vapor condenser (mixture and at the surface). Plant in three stages. Cryo-concentrator.

Homogenizers and shredders

Components: pump, homogenizing valve. Control of the homogenizing valve (mechanical, hydraulic, pneumatic). Effects of the physical parameters on the degree of homogenization. Innovative systems and experimental methods for the homogenization. Single-stage and two-stage crusher, turbo extractor, centrifugal extractor (strainer), shredder hammers.

Plants for special applications

Pulsed electric fields and devices for gas-plasma treatments: constructive and functional aspects and food applications.

Refrigeration systems

Phase diagrams: pressure(p)-volume(v), p-temperature(t), p-v-t. First and second principles of thermodynamics. Enthalpy(h) and entropy(s). Freezing machine. Ideal vapour compression refrigeration cycle. Standard cycle and its variations. Cycles representations in the p-h and t-s plans. Efficiency of the refrigeration cycle. Multi-stadium systems: vapour bubbles extraction and intermediate cooling. Compressors, evaporators, condensers, expansion valves: mechanical and thermodynamic aspects. Refrigerants characteristics. Structures and freezing plants for the agri-food storage "at positive temperature" and for the deep-freezing, thermal load calculation and dimensioning. Control of the atmosphere in the cooling cell.

Safety and control of plants

Legal and normative framework in Europe on safety. Directive 2006/42/EC and Italian Law Decree 2010/17. Directive 89/391/EEC and Italian Law Decree 2008/81. The instrumental control of the machines: acquisition and signal processing, sensors and functional aspects of construction, signal conditioners, analog to digital converters, data processing. The ISO1999/2013: noise measurement, analysis and effects. Specificity on the safety of refrigeration systems.


Educational material distributed in classroom and downlodable from the exchange folder and from "Virtuale". Other material downlodable from Internet: diagrams, directives, standards. Records from lectures.


Dario Friso, Ingegneria dell'industria alimentare, Operazioni unitarie del food engineering, Macchine e impianti, Cleup, 2013 (for consultation).

W. F. Stoecker, "Manuale della refrigerazione industriale", Tecniche nuove, Milano, 2001.

Teaching methods

Lessons with drawing and projection of schemes of plants and equipment. Lessons on theoretical aspects on food plants and refrigeration systems. Exercises on the performance of some plants for food processes. Drills mainly consisting in calculation of the thermodynamic parameters for the refrigerating cycles analysis, thermal loads determination for the dimensioning of plants for "positive temperature" refrigeration and deep-freezing, finding of norms and laws on safety from Web.

Assessment methods

Final exam quiz-type with multiple choice and single answer, with the use of the PC (21 questions; duration of the test: 95 min).
See "Virtuale" for details on exam method.
The exam is designed to assess the student learning on all the arguments covered in class. In particular, the following aspects are evaluated:
1) the theoretical and technical knowledges;
2) the ability of critical choise;
3) the ability, by numerical calculation, to determine some parameters related to the subject of study.
During the course, the teacher has also opportunity to assess the degree of attention and critical participation of the students in the lectures and exercises looking for, although it is not required, the involvement of the students in the analysis and discussion. This is useful to better modulate the teaching according to the student's answer, without which the result of this interaction can represent prejudice for the final evaluation.
Call dates for each session: two.

Teaching tools

Personal computers connected to Internet used by the teacher in classroom. Blackboard. Whiteboard with camera. Audio system. Video projector. Library. Computer room. Food engineering lab.

Office hours

See the website of Luigi Ragni