This document discusses equipment for size reduction of fibrous foods. It begins by introducing size reduction and its benefits in food processing. It then classifies size reduction methods and discusses the forces involved like compression, impact, and shear. It explains the principles and mechanisms of size reduction. Finally, it describes specific equipment used for slicing, dicing, shredding, and pulping fibrous foods.

1. Equipments For Fibrous Foods
Name:-Zahid Parvaiz Lone
Roll No:- 19
Enrollment No:- 2204911017
Batch:- 2022
Course:- MSFST
Topic:- Equipments for Fibrous Foods
Submitted to :- Dr. Basharat Yousuf

2. CONTENTS
 INTRODUCTION TO SIZE REDUCTION
 BENEFITS IN FOOD PROCESSING
 CLASSIFICATION OF SIZE REDUCTION
 FORCES USED IN SIZE REDUCTION
 PRINCIPLEAND MECHANISM OF COMMINUTION OF FOOD
 ENERGY FOR SIZE REDUCTION

3. Introduction to Size Reduction
 Size reduction is the process of
reducing bigger solid pieces of food
into smaller one of desired size and
shape.
 Size reduction is also known as
comminution/Diminution/Pulverizatio
ns.
 Size reduction of solid food done by
grinding ,compression or impact
forces.
 Size reduction also known as
Emulsification or homogenisation
when applied to immiscible
liquids(e.g oil globules in water).

4. Benefits in food processing
 Increase in surface to volume ratio of food which in turn increases rate of drying,
heating and cooling
 Improves efficiency and rate of extraction
 Facilitates mixing and blending
 Facilitates heat exchange ,chemical and biological reactions
 Improves absorption
 Improves rate of handling characteristics
 Asmaller range of particle size allows complete mixing

5. Size reduction and emulsification
 Size reduction and emulsification improve quality or sustainability of food for
further processing rather than having any preservative effect.
 In some foods they promote food degradation by the
 Release of naturally occurring enzymes from damaged tissues .
 By microbial activity .
 Oxidation at the increased area of exposed surfaces, unless other preservative
treatments are employed.

6. Classification of Size Reduction
 Chopping ,cutting ,slicing and
dicing
 Large to medium
 Stewing steak
 Sliced fruit for canning
 Medium to small
 Sliced green beans and diced
root
 Small to granular
 Minced or shredded meat
 Flaked fish or nuts
 Shredded vegetables

7. Classification of Size Reduction
 Milling to powders or pastes of
increasing fineness
 Grated products
 Spices
 Flours
 Fruit nectars
 Powdered sugar starches
 Smooth paste
 Emulsification and
Homogenization
 Mayyonise
 Milk and essential oils
 Butter
 Ice Cream and margarine

8. Forces used in size reduction and its principle
 Compressive:- used for course
crushing. e.g crushing rolls
 Impact:-general purpose forces
 Shear or attrition forces:- used
in pulverization when size of
products reach micrometer range.
e.g hammer mills
 Ultra fine grinding:- used in sub
micron range of particles.e.g disc
attraction mill
 Cutting:-gives a definite particle
size and may even produce a
definite shape.e.g rotary knife
cutter

9. Stress strain diagram for various foods
(Size reduction mechanism)
STRESS SRAIN
FRACTURE
IN LINES OF
WEAKNESS
RELEASED
HEAT
In most size reduction equipments
intially all three forces are present
When
initially
stress is applied to a f
o
o
d
s
t
r
a
in is absorbed causing
deformation of the tissue.
If the strain does not exceed critical
limit food returns to its original shape as
soon as the force is removed and stored
energy is released as heat

10. Energy for size Reduction
 Energy for size reduction depends upon the
 Hardness of the material
 The tendency of material to crack(friability)
 Energy required to reduce the size of solid foods is calculated using one of the three laws as
under:-
1. Kick’s law states that the energy required to reduce the size of particles is proportional to the
ratio of the initial size of a typical dimension (for example the diameter of the pieces) to the
final size of that dimension:
• E(J)= Kk ln (d1/d2) where E (J) the energy required per mass of feed,
• KK Kick’s constant,
• d1 (m) the average initial size of pieces, and
• d2 (m) the average size of ground particles.
• d1/d2 is known as the size reduction ratio (RR) and is used to evaluate the relative
performance of different types of equipment.

11. continued
 Rittinger’s law states that the energy required for size reduction is proportional
to the change in surface area of the pieces of food (instead of a change in
dimension described in Kick’s law):
E= Kr (1/d2-1/d1)
where KR Rittinger’s constant
 Bond’s law is used to calculate the energy required for size reduction from:
•
E/W= √(100/d2- √(100/d1)
where W (J kg 1) the Bond Work Index (40 000–80 000 J kg 1 for hard foods
such as sugar or grain (Loncin and Merson, 1979)), d1 (m) diameter of sieve
aperture that allows 80% of the mass of the feed to pass and d2 (m) diameter of
sieve aperture that allows 80% of the mass of the ground material to pass.

12. Continued
 In practice it has been found that Kick’s law gives reasonably good results for
coarse grinding in which there is a relatively small increase in surface area per unit
mass.
 Rittinger’s law gives better results with fine grinding where there is a much larger
increase in surface area
 Bond’s law is intermediate between these two.

13. Size reduction of fibrous foods
 There are four main types of size reduction equipment, classified in order of
decreasing particle size as follows:
 slicing and flaking equipment
 dicing equipment
 shredding equipment
 pulping equipment.

14. Size reduction of fibrous foods
 Slicing and flaking equipment:
 In some designs food is held
against the slicer blades by
centrifugal force and each slice
falls away freely
 Newer designs are computer
controlled and can be
programmed easily by operators
to bulk slice and stack a range of
products including cheeses, pizza
toppings, cooked meats,
cucumber and tomato, and then
apply them onto sandwich bread
 Flaking equipment for flaked
fish, nuts or meat is similar to
slicing equipment. Adjustment of
the blade type and spacing is used
to produce the flakes.

15. continued
 Dicing equipment:
 For dicing, vegetables, fruits and
meats are first sliced and then cut
into strips by rotating blades.
 The strips are fed to a second set
of rotating knives which operate
at right angles to the first set and
cut the strips into cubes.
 Shredding equipment:
 Typical equipment is a modified
hammer mill in which knives are
used instead of hammers to
produce a cutting action.

16. continued
 Pulping equipment:
 This uses a combination of
compression and shearing forces
for juice extraction from fruits or
vegetables, for cooking oil
production and for producing
pure´ed and pulped meats