Its a ppt that covers all most all aspects of Extrusion procedure, changes and products as well.

1. Doctor M.Waseem Riaz Sabri
I.U.B, Islamia Bahawalpur

2. Line of learning contents
• Extrusion
• Why gain popularity
• Extruders types
• Extruders components
• Principle of operation
• Physicochemical changes during extrusion
• Extrusion products
• Extrusion vs pelleting

5. Why gain
popularity?
Versatility
Cost effective
High
Productivity

6. Extrusion
Developed in 1870 for sausages
Single screw extruder was evolved
in1930
Twin screw extruder in 1940s

7. Based
on
Method
of
operation
Cold extruders
Hot extruders
Type of
construction
Single screw
extruders
Twin screw
extruders
Types of
extruders

9. Twin screw types
1) Co-rotating
a) Intermeshing b) Non-intermeshing
2) Counter rotating
a)
Intermeshing
b) Non-
intermeshing

13. Cylindrical
Rotates in grooved barred made of alloy or stainless steel
Length to diameter ratio 2:1 and 25:1
Typical screw speeds are 150–600 rpm
Compression is achieved by back pressure
Die pressures vary from 2000_103 Pa for low viscosity products
17 000_103 Pa for expanded snack foods
Features of
single screw
extruder

14. i. Rotate within a ‘figure of 8’ shaped bore
ii. Has segments for different actions
iii. Designed in 10:1 length to width ratio
Twin screw features

17. Extruders
part
Pre-conditioning
system
Feeding
system
Screw or
worm
Barrel
Die and the
cutting
mechanism

20. When preconditioning is required??
Uniform particle
hydration
Reduces retention times
within the extruder
Increases throughput
Increase the life of the
equipment.
When feed material
contains moisture
content of 20-30%
Preconditioning
favors

21. Feeding
system
Guarantee a
constant feed
material
Non-interrupted
feeding of the
raw materialsFor an efficient
Uniform
functioning of
the extrusion
process

22. Determine
cooking degree
Gelatinization
Starch and
protein
denaturation
Final product
quality
Importance of
screw

23. Barrel
Its
surrounded
by sleeve
Sleeves can
be solid
But often
permits the
circulation of
steam and
heat

24. Die
Give shape to the
final product
Increase internal
pressure of extruder

25. Physico-chemical changes during extrusion
Major changes occur
during extrusion
process are:
1) Changes in
starch
2) Changes in
proteins
3) Changes in
lipid
4) Changes in
fibers

26. General changes during extrusion
Bubbles rapidly expand as the superheated water is released very quickly at atmospheric
pressure
Recombination
Thermal degradation
Fragmentation
loss of native conformation
Cleavage
Binding

27. • Changes in starches
• Gelatinization
its define as ‘the irreversible destruction of crystalline order in starch granules so
that the surface of each molecule is accessible to solvents or reactants

28. Gelatinization
is brought by
Moisture
combination
Heat
Pressure
difference
By PH
modification.

29. Gelatinization
occurs in 3
phases
Phase 1
Phase 2
Phase 3
slow absorption
of water
immense
absorption
Step by
step
changes

31. Changes in protein
Disulfide bonds are broken and may re-form.
Electrostatic and hydrophobic interactions favor the formation of insoluble
aggregates.
The creation of new peptide bonds during extrusion is controversial
High molecular weight proteins can dissociate into smaller subunits.
Enzymes losses their activity due to high temperature and shear

32. Changes
in
lipidsfat
Melts
into small
droplets
Reduces
friction
Mixed in
feed
materials

33. Redistribution of
insoluble fiber to
soluble
Rupture of covalent
and noncovalent
bonds between
carbohydrates and
proteins associated to
the fiber
Resulting in smaller
molecular
fragments, that
would be more
soluble

34. Positive effects of extrusion

37. Effects of
extrusion on
vitamins activity

39. Cereals
Snacks foods
Pet food AquafeedBaby food
Extrusion products

40. cereals
• Cooked wheat, barley or oats in the form of porridge ready-to-eat cereal
Flakes Co-extruded
products
Directly
expanded
products

41. Snacks
Light meals or a partial replacement for a regular meal. Often eaten
while travelling or watching sports and other entertainment
Directly
expanded
snacks
Indirectly
expanded
Snacks
Shape
diversity

43. Pet food
Filled products
Multicolored
product
Kibbles ,for cat &
dog

44. Aquafeed
Floating
Sinking
Fast sinking

47. Single-screw extruders includes:
• Direct expanded corn snacks
• Texturized vegetable protein
• Ready-to-eat breakfast cereal
• Production of full fat soy
• Pet foods
• Floating and sinking aquatic feed
• Production of baby foods
• Rice bran stabilization
• Precooked or thermally modified starches, flours and
grain
• Breading

48. Twin-screw extruders products
• Co-extruded snacks
• • food gums
• reformed fruit bits and sheets
• topping and bakery analogs
• precooked pasta
• noodles, spaghetti and macaroni
• imitation nuts
• third generation snacks
• • Semi-moist food
• soup and gravy mixes
• sugar crust liqueurs
• pet treats
• three-dimensional snacks
• three-dimensional confections and
toffees
• bread-like products (crisp bread)
• pastry Doug
• texturized vegetable protein (soy)
• wheat gluten textured products
• cheese and casein products
• meat analog
• texturized vegetable protein from
partially defatted soy flour
• stabilization of rice bran
• multicolor food and snacks
• meat and power bars
• special energy bars with resin
filling
• marshmallow products
• cereals and corn flakes

49. Extrusion Pelleting
An extruder will expand the pellet by
gelatinization of the starch, expansion and
increased porosity thus the reduction of the
density.
A pellet mill shapes the pellets by compression
through long land dies thus the pellet is dense.
No need for the addition of a pellet binder in most
cases.
In most cases, a pellet binder is need in the
formula to facilitate the cohesion of the pellet.
Extrusion allows you to control the buoyancy of
the pellet by the degree of starch gelatinization.
Do not control the buoyancy of the pellet
Extrusion allows you to use higher level of oil or
fat without creating much fines
Does not allows to use high levels of oil or fat
Shaping is only one part of extrusion pellet mill is mainly utilized to shape or produce a
pellet of different shapes.