Engineering Properties
Dr. Muanmai Apintanapong
Rationale:
• In handling, processing, storage, and
distribution of foods at various stages,
engineering properties play a key role in
design of the equipment, processes, and
monitoring of the quality. A knowledge of
engineering properties may lead to greater
efficiency in production and utilization of food
materials, less waste, and foods of higher
quality and lower cost to the consumer.
Catalog Description:
• Principles involved in the measurement
of physical characteristics; mechanical;
thermal; electrical; and optical properties
of food materials; analysis; interpretation;
and application of experimental data in
relation
to
harvesting;
handling;
processing;
storage;
and
quality
evaluation.
Course Outline
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Introduction
Structure, Composition and Retention of
Water in Food Materials
Physical Characteristics
Mechanical Properties
Thermal Properties
Electrical Properties
Optical Properties
Introduction
• Importance
– Handling and processing of plant and animal
materials were done by various means such as
mechanical, thermal, electrical, optical, sonic
techniques and devices.
– Knowledge of these properties:
• To design machines, structures, process and controls
• To develop new consumer products
• To determine the efficiency of a machine or an operation
Physical Characteristics
• Such as: shape, size, volume,surface
area, density, porosity, color,
appearance.
• Use to design a specific machine,
analysis of behavior of product in
handling of material
• Heat transfer calculation
– Cooling curve
– Transient heat transfer
• Aerodynamic characteristics
– Assumption of the shape of material
– Important design parameters in conveying of solid
materials by air or water
– Terminal velocity, drag coefficient, Reynolds
number
• Harvesting, sorting and grading
– Surface color and appearance
– Size and shape
Mechanical properties
• During
harvesting,
threshing
and
handling,
mechanical
damage
is
seriously affected to quality of product.
Mechanical properties
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Biological Systems and Mechanical Properties
Food Rheology and Visco-elastic Characterization
Texture Evaluation of Foods
Aero- and Hydrodynamic Properties
Flow Behavior of Granular Materials and Powders
Selected Applications in Design of Equipment and
Processes
Mechanical properties
• Compressive strength, impact, shear
resistance: studying size reduction, seed
resistance to cracking under harvesting
and handling.
• Static and sliding coefficient: design and
predict motion of material in harvesting
and handling equipment.
Mechanical properties
• Compressibility, expansion characteristics,
coefficient of internal friction, cohesion,
elasticity: studying compressibility and
determine methods of compressing and
packaging.
• Shearing resistance and bending strength:
nature of cutting process and energy
requirement in mowing machine.
Mechanical properties
• Mechanical harvesting, bulk handling,
transporting and storage: need basic
information in mechanical properties.
• Mechanical
handling
results
in
deformation and flow: rheological
properties.
Thermal properties
• Thermal processing: heating, cooling,
drying, freezing
• Thermal characteristics: specific heat,
thermal conductivity, thermal diffusivity,
surface conductance, emissivity
Electrical properties
• Electrical conductance, capacitance
properties: used in moisture content
determination in cereal grain.
• Electrical resistance methods: measure
cotton fiber length distribution and
fineness of wool fiber.
Electrical properties
• Conductivity of seed: ability of seed to
hold surface charge
• Impedance technique: to determine the
extent of injury to plant tissue
– Dead tissue = no capacitance
– Uninjured and healthy tissue = has
resistance and capacitance comprising an
impedance
Electrical properties
• Dielectric heating: heating due to its own
dielectric losses when placed in an
electrodynamic field.
• Electromagnetic radiation: radiofrequency,
infrared, visible, ultroviolet, x-rays, gamma
rays
– Heating effects (long wavelength and low energy
range)
– Chemical effects (shorter wavelength and higher
energy range) causing ionization of atoms
Optical properties
• Light transmittance and reflectance
properties: use for electronic sorting and
grading, maturity and surface color
determination and study on interior
characteristics.
Textbooks and Reference books
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M. J. Lewis: Physical Properties of Foods and Food
Processing Systems, Woodhead Publishing Ltd.,
Cambridge, UK, 1996.
N. N. Mohsenin: Physical Properties of Plant and
Animal Materials, Gordon and Breach Science
Publishers Inc., New York, 1986.
S. Rahaman (ed.): Food Properties Handbook, CRC
Press, Boca Raton, 1995.
M. A. Rao, and S. S. H. Riviz (eds.): Engineering
Properties of Food, 2nd Edition Marcel Dekker, New
York, 1994.
Journal and Magazines
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Transactions of ASAE
Journal of Food Engineering
Journal of Food Science Engineering
Journal of Food Science
Grading System
• The final grade will be based on the following
weight distribution:
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short tests (10%)
laboratory assignments (30%)
midterm exam (20%)
final exam (40%)
• The exams are divided into two parts (closed
and open book exams).