Processing and Food Engineering

1. ENGINEERING PROPERTIES OF SEEDS

2.  Physical properties
 Mechanical properties
 Thermal properties
 Electrical properties
 Optical properties

3. Physical Properties Of Biological Materials:
• Shape
• Size
• Volume
• Sphericity
• Density
• Porosity
• Color and appearance

4. Physical properties are important in many
problems associated with design of a specific
machine or analyses of the behavior of the
product in handling of the material

5.  Size and shape are inseparable in a physical
object.
 Both are necessary if the object is to be
satisfactorily described
Importance

6. Shape Description
Round Approaching spheroid
Oblate Flattened at the stem end and apex
Oblong Vertical diameter greater than the horizontal dia.
Conic Tapered toward the apex
Ovate Egg-shaped and board at the stem end
Oblique/ lopsided Axis connecting stem and apex slanted
Obovate Inverted ovate
Elliptical Approaching ellipsoid
Truncate Having both end squared or flattened
Unequal One-half larger than the other
Ribbed In c/s sides are more or less angular
Regular Horizontal section approaches a circle
Irregular Horizontal c/s departs materially from a circle

8. Definition:
Roundness is the measure of the sharpness of the
corners of the solids
Methods of estimation:
1. Roundness = Ap/Ac
Where,
Ap = largest projected area of object in natural
rest position.
Ac = area of smallest circumscribing circle.

9. ROUNDNESS AND SPHERICITY

10. 2. roundness= Σr/NR
Where, r = radius of curvature as defined in fig.
1.2
R = radius of max. inscribed circle
N = total no. of corners sumed in numerator
3. Roundness ratio= r/R
Where , R = mean radius of object.
r= radius of curvature of the sharpest corner

11. Importance
Spheicity gives shape character of the solid
related to that of the sphere of the same
volume.
It is useful in determining the volume of
hoppers.

12. Sphericity=de/dc
Where,
de= dia. of sphere of the same vol. of object
dc = dia. of smallest circumscribing sphere or
longest dia. of the object

13. SCREW GAUGE FOR SPHERICITY MEASURMENT

14.  Drying and storing of hay, design of silo and
storage bins, mechanical compressing of ensilages
.
 Stability of feed pellets and wafers.
 Separation from undesirable materials .
 Determine the purity of seeds separation and
grading.
 Maturity evaluation.
VOLUME AND DENSITY
Importance

15. PLATFORM SCALE METHOD
A simple techniques applies to labs objects such as
fruits vegetables, the fruit is first weighed on the
scale in air and then forced into the water by
means of the sinker rod then the second reading of
the scale with the fruit submerged minus the
weight of container and water is the weight off the
displaced water which will be used in the following
expression calculate volume
Volume (m3) = wt. of displaced water (kg)
wt. density of water (kg/m3)

17. Knowing the wt. in air and the volume, wt.
density of the fruit is then obtained by ratio of wt.
to volume. At the same time sp. Gravity is
calculated from
Sp. Gravity = wt. in air x sp. Gravity of water
wt. of displaced water

18. SPECIFIC GRAVITY BALANCE FOR
MEASURMENT OF VOLUME, DENSITY

19. For smaller objects such as small fruits, bees
and beans, kernels of corn, etc. and analytical
balance or more conveniently a sp. Gravity balance
can be used to the determine volume density and
sp. gravity employing the following expression
Volume = wt. in air – wt. in water
wt. density of water
Sp. Gravity = wt. in water [Sg]l
wt. in air – wt. in water
Where, [Sg]l = sp. Gravity of water

20. Air Compression Pycnometer
(sp. gr.)

21. Importance
 Determination of voids space of agricultural
material.
 The percent voids of materials such as
silage, hay, grain and other porous material
is often needed in air flow and heat flow
studies as well as other applications.

22.  POROSITY=% of volume of inter grain
space / total volume of grain bulk

23. DAYS APPARATUS FOR POROSITY
MEASURMENT
3P
3P1P
1V
2V 


24.  For selective separation in the field as
subsequent handling and processing.
 In selective harvesting of fruits and
vegetables, in sorting and grading at post
harvest and during storage.

25. Some Mechanical Properties Of Biological
Materials
 Compressive strength
 Impact & shear resistance
 Coefficient of friction
 compressibility & expansion characteristic

27.  It is necessary in studying size reduction of
cereal grains.
 Useful in mechanical harvesting , bulk
handling , transporting & storage of fruits &
vegetables.

28.  It is important to know seed resistance to
cracking under harvesting and handling
conditions.
 From an energy standpoint, used to
determine the best method (shear, impact or
crushing ) to breakup or grind grain.

29.  The co. of friction b/w granular materials is
equal to the tangent of the angle of internal
friction for the material.
 Static & sliding coefficient are needed for
rational design and predicting motions of the
material in harvesting and handling
equipments.
 In determining the pressure of grain and
silage against bin walls and silos.

30.  Important in studying compressibility of
materials and determining method of
compressing and packing.
 Useful in storage of grains fruits &
vegetables.

31.  Following are some thermal properties of
biological materials;
 Specific heat
 Thermal conductivity
 Thermal diffusivity

32.  Thermal properties are important for
processing such as heating ,cooling , drying
& freezing .
 Specific heat is important in heat treating
applications where the germination and
viability of seeds may be endangered if
critical temperature or time of heating
exceeds.

33.  A heat balance for a heating or cooling system
cannot be attempted without knowledge of
heat capacity of materials.
 In fruits & vegetables the action of enzymes
and microorganisms causing deterioration can
be controlled by low temperature.
 Thermal properties are important for design of
the equipment and predicting of the processes

34. Following are some electric properties;
 Electrical conductance
 Electrical resistance
 Impedance
 Dielectric heating

36.  Used in moisture content determination.
 Electromagnetic radiations are used in
agricultural product .

37.  This method employed for precise
measurement of cotton fiber length
distribution and fineness of wool fiber.
 Used for separation and cleaning of
agricultural seeds.

38.  Used to determine the extent of injury to
plant tissues due to frost , poisoning by spray
or other means of damage.

39.  Used in drying plastics , ceramics &other
non-conducting materials.
 For inactivating the enzymes in cotton seed.
 Controlling insects &fungi in seeds .
 Drying rice & other grains for storage.
 Used in heat treatment of seeds.

41. LIGHT TRANMITTANCE & REFLECTANCE
 This are important in electric sorting &
grading.
 Maturity & surface color determination.
 To study interior characteristics of fruits &
vegetables.