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

– 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

• 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

• 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

• 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: – short tests (10%)– laboratory assignments (30%) – midterm exam (20%) – final exam (40%)

• The exams are divided into two parts (closed and open book exams).