1. OIL AND FAT
TECHNOLOGY )
Abdul Moiz DOta

2. Handling & Storage of
Oil-Bearing Materials
The handling and storage of oil-bearing materials
is one of the most important phases of oil seed
processing.
The vegetable oils and feed industries are
dependent for successful operation upon
obtaining high yields and product of good
quality from their raw material.
Excessive biological activity in the seeds, either
in the field prior to harvesting or subsequently
during storage, will result in a reduction both in
the quality and the yield of oil and meal.

3. The handling and control of the raw
materials for the oil seed industry can
be primarily characterized by the short
harvest season, by the necessity to
move them into protected storage in
minimum time, and by the required care
before they can be processed. But they
can be treated and stored successfully
with minimal deterioration long enough
to allow the processing industry to
operate throughout the year.

4. Sunflower seed, soybeans, cottonseed,
rape seed and other oil seeds are subject
to damage primarily from biological
actions, which are accelerated by high
moisture content, foreign material,
physical damage, and such adverse
climatic conditions as frost or rain before
harvest.

5. Effects accompanying deterioration of seed
during storage
 Respiration : In the presence of oxygen as the
oxidizing agent, organic food stuffs are oxidized to
form water and carbon dioxide as the end product.
exothermic reaction
C6 H12O 6 + O2
6 CO2 + 6 H2O + energy
Respiration intensity;
Sound seed
–
Damaged seed –
low m.c.
0.1ml CO2 /g seed.day
high m.c. 5.0ml CO2 /g seed.day

6. The respiratory quotient, defined as the
ratio of carbon dioxide evolved to
oxygen absorbed, is an indication of the
class of substances undergoing
oxidation.
In aerobic respiration;
it is theoretically unity if the subctances
are carbonhydrates,
but less than unity if they are proteins or
fats, which are less rich in oxygen.

7. 
Enzymes :
(a)Lipase. This enzyme catalyzes the reaction;
1
glycerol + 3 fatty acid
triglycerid + 3 water
2
1
synthesis t.g
2
hydrolysis t.g
(b) Catalase and peroxidase. Both of these enzymes react
with hydrogen peroxide.Catalase will decompose
hydrogen peroxide while peroxidase utilizes it for
further oxidation.
2 hydrogen peroxide
2 water + oxygen

8.  Influence of moisture content :
Oil seeds are best stored at low moistures where
respirotary and enzymic activities, germination
and mold growth are inhibited. This maximum
acceptable moisture level is known as “critical
moisture level (CML) ”.
The moisture content of the nonoil portion of the
seed rather than the whole seed is the important
factor in oil seed deterioration.
 CML is relatively high for seeds of low oil
content.
 CML is relatively low for seeds of high oil
content.

9. Safe humidity for starchy food grains
16%
Oil content of soybean
Non-oily part of soybean
…….
…….
22%
78%
Critical moisture level 0.78 x 16% = 12.5%

10. CML of oil seeds
Hulls (%)
Rape seed
14
Palm kernel
Sunflower seed 28
Cottonseed
48
Soya beans
8
Fat (%)
40
52
43
18
20
CML(%)
7.0
8.0
8.5
10.0
12.0

11.  Influence of temperature.
In the case of soya beans and similar oilseeds where
deterioration appears to b primarily a result of the
growth of microflora, the storage temperature does
not appear to be a major factor. However, temperature
is very important factor in storage of cotton seed. The
respiration of cotton seed is markedly temperaturedependent. The insulating effect of linters on
cottonseed contributes to the peculiar tendency of
this seed to heat in storage.
It is because of the undesirable effect of high
temperature that most seed houses are equipped with
aeration ducts and large ventilating blowers to cool
the seed.

12.  Storage method
Warehouses (Muskogee type seed
houses)
Bulk storage in warehouses on flat floors
has the advantage of easy control of oil
seeds, like cottonseeds, sunflower
seed, corn germ, further meals etc. To
prevent self heating or autocombustion
of the seeds, recycling by horizantal and
vertical transportation means is
recomended.

13. Muskogee type seed store
Oil seed
Belt
conveyer
Oil seed bulk
Section through storage building

14. Preparation of Oil-bearing
Materials
 Cleaning
foreign materials
 Delinting for cottonseed
 Dehulling
hulls
 Flaking
 Cooking
moist
lints

15. CLEANING
 Cleaning
is important not only to ensure the good quality
of the final products oil and meal but also to avoid
premature wear of the preparation equipment.
 The removal of foreign materials from oil seeds is done by
cleaning machines working on mechanical, pneumatic and
magnetic principles.
Cleaning machines;
Screens
Aspirators
Magnets
Shape sorters

16.  SCREENS
Screening is the seperation of mixtures of
different sizes into fractions; the portion
staying behind being oversize, the
portion passing through being
undersize.
 Rotating screens
 Vibrating screens

17. Drum screen

18. Vibrating screen

19.  ASPIRATORS
In order to seperate impurities or fractions
of different density, pneumatic means,
like air nozzles and aspirators are used.

20.  MAGNETS
Permenant or electromagnets enclosed in
a rotating aluminium drum are used in
feeders to distribute the material
uniformly over the whole active width of
the drum.The magnetic material collected
is removed by a blade on the onomagnetized half and, in this way, it
remains seperated even in the case of
power failure

21. Self cleaning rotary magnets
aspirator
Seed inlet
Rotating drum
Stationary
magnet
Cleaned seed
İron
parts

22. DELINTING
(for cottonseed)
cottonseed
lints (8-12%)
Hull (40-45%)
Delinting process
to remove the remaining lint from cotton seed
Aims of delinting : 1)increase oil yield 2)obtain first- and second- cut linters

23. Delinter

24. Cutting operation
cottonseed
seed feeder
cut lints
saws
delinted
seed
brush
Saw teeth

25. Method of delinting cotton seed
comprises the steps of passing the
cotton seed through a saw delinter to
remove a substantial portion of the
lint, preferably at least 40%, and
thereafter passing the partially
delinted seed through a brush delinter
to remove substantially all of the
remaining lint.

26. Cottonseed Delinting Equipment

27. DEHULLING
Dehulling is a process of removing hulls from the oilseeds
for obtaining high quality edible oil by the processing of
kernels. This reduces fibrous content of the meal and
increases the marketability as stock feed. About 99% of oil
is stored naturally in kernels and the hulls contain not
more than 1% oil.
If the hulls are not removed they reduce the total yield of oil
by absorbing or retaining oil in the pressed cake. In
addition to this the wax and colouring matters present in
the hulls get mixed with the expressed edible oil. This
necessitated the refining process, and therefore, increase
the production cost of edible oil.
Moreover, processing oilseeds without dehulling reduces the
capacity of the extraction equipment in addition to more
repair and maintenance charges.

28. Approximate Hulls and Kernels Percentage in different
seeds
% oil
% kernel
% hull
whole
kernel
husk
Cottonseed
55
45
19
30
1-2
Rapeseed
82
18
42
-
-
Sunflower
75
25
22-36
Soybean
93
7
18
36-55
19
1-2
0.6

29. HULLER
The hulling machines used for the
decortication of medium-sized oil
seeds with a flexible seed coat, such
as cottonseed, sunflower seed and
peanuts, are of two principle types;
 Bar hullers
 Disc hullers

30. Bar huller
The rotating member of a bar huller is a cylinder equipped on its
outer surface with a number of slightly projecting,
longitudinally placed, sharply ground, square-edged knives or
bars.Opposed to the cylinder over an area corresponding to
about one-third of its surface is a concave member provided
with similar projecting bars.The seed are fed between the
rotating cylinder and the concave member, and the hulls are
siplitted as the seeds are caught between the opposed
cutting edges.The clearence between the cutting edges may
be adjusted for seed of different sizes.
seed
Bars (concave surface 1/3)
Square-edged knives

31. Disc huller
The disc huller consists of vertically mounted discs,
one of which is stationary and the other
rotating.The seeds are fed to the center of the
discs and are discharged at their periphery by
centrifigal force.
Adjust according to seed size
Rotating disc
seeds
Stationary disc

32. The moisture content of seed effects the
efficiency of dehulling operation.
 Wet seeds are difficult to split cleanly
and may clog the huller.
 If the seeds are very dry, the kernels
may disintegrate excessively.

33. Universal dehulling
Seed
First huller (coars huller)
Hull beater
Kernel Hull Uncut seed
Second huller
Hull beater
Kernel Hull Uncutseed

34. FLAKING
The extraction of oil from oil seeds,
either by mechanical extraction or
solvent extraction, is facilitated by
reduction of the seed to small particles.
Flaking is achieved on corrugated roll
stands. Cracking mills with one or two
pairs of rolls are used.
Hammer mills are used for certain raw
materials like palm kernel.

35. Crushing rolls
A roll assembly commonly used for the reduction of oil
seeds consists of a series of five rolls placed one
above the other. The seed is introduced by a feeding
mechanism between the two top rolls.Seed travels
from the top to the bottom of the system, hence it is
rolled four times.
kernel
Corrugated roll
Speed 0.05 m/sec
knife
Smooth rolls
flake

36. Crushing rolls

37. COOKING – HEAT TREATMENT
Effects of cooking process on the physical
and chemical properties of oil seeds;
 The oil droplets in the oil seed are
ultramicroscopic in size. Because of the
increase in temperature they come
together and form larger droplets to flow
from the seed.
 Heating of the seeds causes the protein
to denature and as a consequence, the
emulsion to break and the oil to seperate
from the solid surface of the seed.

38.  Cooking of the seed gives the seed mass
the proper plasticity for efficient
pressing.
 Insolubulization of phosphatides and
other impurities.
 Destruction of molds and bacteria.
 Increase of the fludility of the oil through
increase in temperature.
 In the case of cottonseed, detoxification
of gossypol or related substances.

39. A four – high stack cooker
The cooking of oil seeds is usually carried out in “stack cookers”.These
consist of a series of four to eight closed, cylindirical kettles. Each
kettle is normally jacketed for steam heating on the bottom and is
equipped with a sweep-type stirrer mounted close to the bottom.There
is an automatically operated gate in the bottom of all kettles. The top
kettle may be provided with spray jets for the addition of moisture to
the seed, and each of the lower kettles is provided with an exhaust
pipe with natural or forced draft for the removal of moisture, thus it is
possible to control moisture content of the cooked seed.
Seed flakes
Direct steam
T (0C)
2-3.5 m diameter
50-70 cm high
Sweeper-type stirrer
Exhaust pipe
gates
Cooked flakes

40. STACK
COOKER

41. Cooking of cottonseed
Detoxification
Before cooking, moisture 12.%
Cooking time 90 mn
Final cooking temperature 115 0C
Final moisture 3%

42. Conventional preparation system