PRESENTATION ON

PHYSICAL PROPERTEIS OF Food MATERIALS PFE-502

SUBMITTED BY :-

Er.

OM_SURYAWANSHI

9302528033

M. Tech. (Previous)

Department of APFE

Physical Properties

Mechanical Properties

Thermal Properties

Electrical Properties

Optical Properties

Chemical Properties

Rheological Properties &

Hygroscopic Properties

Important Properties of Food Materials :-

Physical Properties:-

Shape & Size

Density & Specific gravity

Volume

Porosity

Surface Area etc.

It is important in the design of any particular

machine or analysis of the behaviour of the product

during process.

Importance of Physical Properties:-

These properties are necessary for the design of :-

Cleaning unit

Grading unit

Separating unit

Handling unit

Shorting unit

Storing and

drying system.

Shape & Size :-

Shape is the rigid form of body while, Size is the

measurement of dimensions.

Used in :-

Shape & Size of Screen openings.

Selection of Disk

Adjustment of Cylinder Clearance.

Angle of inclination.

Vibration amplitude & Frequency of Screen.

Parameters for determining the shape & size :-

Roundness:- measure of the sharpness of the solid

materials.

Roundness, = Ap/Ac

Ap= largest projected area of object

Ac=area of smallest circumscribing circle

Roundness,=∑r/NR

r= radius of curvature

R= radius of maximum inscribed circle

N=total no. of corners

Roundness,=r/R

r= radius of curvature of sharpest corner

R=mean radius of the object

Sphericity:-

It is the cubic root of volume of solid and the volume of

circumscribed sphere.

It may be defined as the ratio of surface area of sphere having

same volume as that of particle to the surface area of the particle

Ratio of the solid to the volume of circumscribed volume.

Sphericity, = Di/Dc

Di=dia. of largest inscribed circle

Dc=dia. of smallest circumscribed circle

Almost all spherical objects have sphericity approaching 1

The value of sphericity ranges from 0 to 1.

An orange has sphericity of the order of 0.95 and

Paddy has 0.130to 0.1520

Sphericity continues……

Sphericity = [Volume of solid/Volume of circumscribed sphere]1/3

Methods for measuring Size

Vernier calliper :- least count 0.01 cm

Micrometer Method :- least count 0.01mm

Projection Method :- Ac = (A1+A2+A3)

Travelling Microscope

Sieve Analysis Method :- D = 0.10332(2)FM

Instruments for Measuring Shape & Size:-

Vernier Callipers

Screw Gauge

Density & Specific gravity :-

Density = Mass/ Volume (Kg/M3)

Used in :-

Design of Silos and Bins

Mechanical composition of silage

Separation of crops

Sorting and Grading

Maturity evalution

Texture and softness

True Density

Bulk Density

Apparent Density

This properties are used in

designing of silos and storage bins,

separation of desirable materials from

impurities, cleaning and grading etc.

Density & Specific gravity…..

Specific gravity = weight in air x specific gravity of water

weight of displaced water

Specific gravity

Methods :-

Suspension Method

Density column Method

Platform Method

Specific gravity balance Method

Relative density bottle Method

Suspension Method

Density of mixture = V1 S1 V2S2 V1 V2

Density of grain = Density of mixture

Where V1 = volume of one liquid

S1 = specific gravity of one liquid

V2 S2 = Respectively of other liquid

Density column Method

Carbon tetrachloride

Cyclohexane

Platform Method

Weight of fruit in air = W1 gm

Weight of fruit in water = W2 gm

Specific gravity of fruit = W1 / (W1 – W2)

Specific gravity balance Method

If the solid is heavier than water

If the solid is lighter than water

If the solid is heavier than water

Volume = Weight in air – weight in water / weight

density of water

Specific gravity = [weight in air / weight in air – weight

in water]x (Sg)L

Where, (Sg)L = Specific gravity of water

If the solid is lighter than water

Specific gravity = (Wa) object / (Wa - Ww) both –

(Wa -Ww) sinker x (SG)L

Where Wa = weight in air, Ww = weight in water

Relative density bottle Method

Weight of bottle in air = W1

Weight of bottle + Water in air = W2

Weight of bottle + toluene in air = W3

Specific gravity of toluene = W3 – W1 / W2 – W1

Weight of the bottle + 10 of the grain + toluene to cover

the sample = W4

Specific gravity of grain = (S.G. of toluene) x Weight of

the grain / weight of toluene displaced by the grain.

Porosity:-

It is relationship between volume of

the inter-grain space to the total column of

grain mass.

Porosity = - B g

Where, B = bulk density of material,

g = True density of material

Porosity determination Method:-

Air compression pycnometer method

Porosity Measuring Method

Surface Area:-

Leaf Surface Area:-

Graphical Method

Air Flo Planimeter :- Two perforated plates Having 100 holes per square cm.

Fruits Surface Area:-

Apple, S=6.72+0.129W

Pears, S=7.49+0.99W

Eggs, S=4.82W0.66

Plum, S=2.18+0.149W

Where, S= surface area in sq. inch,

W= fruit weight in gm.

References:-

Singhal OP & Samuel DVK. 2003. Engineering properties o

Biological Materials. Saroj Prakashan

Sahay KM & Singh KK. 1994. Unit operation of Agricultural

Processing. Vikas Publ. House.