The cold pressing of
vegetable oil has been proven in several countries as a viable small
industry for the individual entrepreneur or company wishing to add
value through vertical integration within its production or
distribution chain and especially when targeting niche products.
Specialty oils with high value low volume operations are especially
viable for small operations due in part to the lack of interest by
the large scale industry.
That is not to say that plants in the capacity range of 1 to 5
tons per hour where mechanical expelling or pressing is used, is not
viable in the case of the commercial seeds such as sunflower and soy
beans where for instance low fat oil cake is required for the
processing of animal feed or human foodstuffs. With high quality
equipment and the correct pre-processing, viable yields can be
obtained.
The Expeltec oil expelling system is presented as a complete
turnkey project in terms of plant and equipment supplied, installed
and commissioned. Components may also be purchased separately so as
to enable the industrialist to make up his own plant. The plant
in standard execution provides for extraction of oil from groundnuts
and sunflower seeds, soy beans and virtually all oil bearing seeds
such as jojoba, apricot kernels, peach kernels, pumpkin seeds, cotton
seeds, copra, tomato seeds, castor seeds, almonds, walnuts,
macadamia, pecan and virtually all seeds with relatively high oil
content are possible feedstocks. The final use of such oil and the
required refining to get it to a specification, are of course all
individual considerations. Usually in the case of high value oils, no
refining other than filtration is required by the end user or oil
traders as the oil's attraction usually lies in its natural smell and
taste that is concentrated when the oil is pressed.
With the widespread use of biodiesel, various oils may be used
that are of low value otherwise, but that may be viable for fuel.
Seeds with aflatoxins that are poisonous for human and animal
consumption can for instance be used for biofuel very effectively as
it has no other commercial value. As such quantities are normally not
that big, it can easily be mechanically pressed when the opportunity
arises.
The commercial growing of jatropha for biodiesel purposes
requires chemical extraction to be viable in the quantities upon
which these projects are based.
Expeltec systems would basically consist of the following:
It is crucual that seeds be received correctly, dried if too
wet to avoid spoiling, stored properly and aerated when required to
maintain quality and finally fumigated when necessary to avoid
losses and to maintain oil quality and quantity. It may also e
necessary to add moisture when seeds are too dry for instance. This
can be accomplished by a dampener to be included after cleaning.
2. Seed cleaning:
This process ensures that the equipment further down the line
is protected from tramp steel, dust, sand and stones which are all
very abrasive as well as poisonous seeds, especially where oil is
pressed for human consumption. Normally no warranty would apply to
any machine downstream if a proper cleanng system is not installed.
ABC Hansen offers cleaners from 2 -3 ton per hour capacity up
to pre-cleaners of 240 tons per hour.
3. Seed dehulling plant
Dehulling is optional in most cases while applying a dehuller
would result in higher yields of oil and higher protein of oil cake
as the fibrous hull absorbs oil when pressing and is not high in
protein by itself. For some oil seeds, some hulls are essential as
fibre to get the product firmly through the screw without turning
into "butter". This is especially the case where oil
content is high.
Various de-hullers can be supplied. In the case of soy beans,
a 1 ton per hour abrasive de-huller removes 99.9% of hulls and
splits 99.9% of the beans. Sunflower dehullers are available as
fllows:
Capacity 500 kg/hr - 1 ton per hour per
machine.
Power 3 kW 380 V Three phase,
Inverter driven
Aspirator unit for air separation
including cyclones
4. Conditioning:
Conditioning may refer to, for instance heat in the form of
extrusion, steam, a parcher, warm air etc. being applied to the
seeds prior to expelling. It may, again be of crucial importance in
some cases while only increasing yield by one or two points in other
cases. This may also relate to the extrusion of oil seeds, prior to
pressing.
5.Extrusion:
This process, when included in a mechanical oil pressing
plant, ruptures the oil cells and ensures the oil is released faster
and easier. The seeds are in some cases heated to neutralise the
tripsin inhibitor as for soy beans, to allow the processing of low
fat oil cake - see section below).
Extruders from InstaPro would generally be used in all ABC
Hansen plants from capacities of 600kg per hour and higher.
The InstaPro range includes the following extruders:
600 Series extruder with capacity 270 to 365 kg per hour.
2000 Series extruder with capacity 1,000 to 1,200 kg per
hour.
9000 Series extruder with capacity 2,700 to 3,600 kg per
hour.
Other than the elected method by which the product is
transported between machines, the oil expeller(s) or oil press or
expressor (as various companies would call the process) would form
the next processing machine.
6. Oil Expellers:
The Expeltec system utilises several presses, depending on
the capacity of the system and the type of seed pressed notably:
The SGC120 for a capacity of around
120kg per hour on sunflower seed intake. This is a low cost machine
with low cost of wear parts and usually used for high value
specialty seeds. A viable business can usually not be run when
pressing commercial oil seeds such as sunflowers or soy on these
presses.
The SGC300 for a capacity of 300kg/hr
based on sunflower seed intake. While still relatively low
capacity, several presses may form a viable production unit for
commercial seeds and may be very profitable when pressing specialty
seeds.
For larger capacities ABC Hansen would
install InstaPro presses which are primarily classed as the
following:
Model 1000 - 15kw for capacities of 350 - 450 kg per
hour.
Model 2000 - 30kW for capacities 700-900kg per hour.
Model 5005 - 40kW for capacities 1,800 to 2000 kg per
hour.
It is not recommended that more than 4-5 presses be operational
for a given capacity unless the maximum presses are used as the
running cost and maintenance cost outweighs the advantage of a
"back-up" press or using several lower cost presses
instead of one or two larger presses.
7. Further processing:
The pressed oil is now pumped to settling tanks and filtered while
the oil cake is usually milled into a meal and bagged after it has
cooled down and used, in most cases, as animal feed. Some vacuum
filters ay be used to extract maximum oil from the sludge.
Filtered cold pressed oil is by far the healthiest oil available as
it retains all the vitamins and minerals as well as the key
important amino acids the human body needs but can not produce. The
Omega amino acids are abundant in some cold pressed oils such as
sunflower, sesame and others.
Once filtered, the processor
may require that the oil be de-waxed. That is simply removing the
waxes that would turn the oil cloudy once the temperature drops to
below 24 ° C or lower in some cases. This is done by cooling the
oil down and filtering it again.
This is where refining of
cold pressed oil should end. All further refining reduces the value
of the oil unless of course some harmful elements must be removed as
in the case of cottonseed oil.
It should be noted that large scale
producers of oil are interested in selling commodities. Their
plants chemically extract from 240 to 1,000 tons and more of seeds
per day. These hungry monsters needs to be fed any seed that is
economically viable to extract. They therefore neutralize all oils,
whether corn oil, cotton seed, sunflower or soy bean simply into
fat in order to blend these oils on a continous basis without
having a perceptible change in taste, smell or colour should one of
the raw material ingredients change.
Some oils, such as soy bean oil has a
dark rusty colour and an unpleasant smell and has to be neutralized
in order to blend. The refining process subjects the oil to very
high temperatures that starts the oxidization process. The acid
wash of oils not only removes the free fatty acids prevalent in
decaying oil, but also the valuable amino acids.
The most important processes of refining then include the
following:
Neutralising: The oil is washed with a caustic soda mix
through which the free fatty acids binds with the caustic soda and
forms soap that is removed from the oil.
Degumming: The oil is washed with water that binds with the
gums in the oil and is then allowed to settle or is centrifuged.
Deodorising: The oil is heated to around 200° C (260 is
flashpoint) under vacuum and dry steam is introduced in the
pressure vessel. The volatiles evaporating at this temperature is
carried off under vacuum with the steam, rendering the oil
tasteless and without smell. At the same time, any water remaining
in the oil is evaporated so a "dry" oil results.
Following these processes, a neutral fat is obtained that
is again artificially coloured to the right "sunflower yellow" and
preserved through addition of citric acid or other preservatives.
Generally we would recommend that high value, low volume seeds be
mechanically expelled. It is doubtful whether mechanical expelling is
able to compete effectively with high volume chemical extraction
plants while there is simply no way that those plants can compete
with small scale mechanical expelling of high value seeds.
The ABC Africa group is able to install
plants for processing of soybeans in various ways.
The soy bean, due to its physiological make-up, requires that
its protein be broken down to cook neutralize trypsin inhibitors
that prevents the intake of proteins in raw form, of grazing
animals. The trick therefore has been to find the most efficient way
to heat soy beans in order to neutralize this effect. This can
be achieved by heating the bean to a sufficient level and can be
done in several ways namely:
Extrusion: A mechanical screw pressing
a large volume of product through a restricted opening thereby
generating heat in excess of 150°C, sufficient to cook the
bean.
Steam: Tthe beans are either batch
cooked or continuously cooked by means of steam in jacketed
vessels.
Parcher: For smaller applications, the
beans are simply heated directly by means of a parcher with either
electric, coal, wood, gas or any other inexpensive fuel. The system
is crude and normally consist of a heated revolving tube where the
beans are heated without being scorched.
Diesel or oil fired rotary drum roasters are efficient and
easy to operate. ABC Hansen offers 1 ton per hour rotary drum
roaster.
Micronising:While this would normally
refer to the micro wave oven as we know it in our homes, in
practice it usually takes the form of infra red heating over a
conveyor - sometimes it just refers to heating elements.
Following the heating of the bean, expelling may take place if
a low fat soy bean oil cake is desired, otherwise, simply milling
the heated bean (and in the case of extrusion, the mutilated bean is
simply cooled) offers a full fat soy bean oilcake.
Full fat soy bean oilcake has only one disadvantage. It has
too much fat relative to protein. The trick for the farmer is to
turn vegetable protein into animal protein or meat in the most
efficient way. He would therefore like to lower the fat in the soy
bean and increase the protein. Of course he can do it in one stroke
- by expelling the fat.
The soy bean has around 33-38% protein which makes it a great
crop. By reducing the fibre - around 15% (through dehulling) and
reducing the fat - another 12% (through expelling), protein takes
up a bigger percentage of the remaining volume. This can go as
high as 46-8 % which increases the price of the remaining soy bean
cake tremendously since farmers purchase fodder in accordance with
the weight it would add to their animals, or protein.
With some 18% fat in the soy bean, around 10-14% oil can be
expelled mechanically. All 18% can be extracted chemically through a
hexane process. (Hexane is a petrochemical cousin of benzine, the
latter outlawed as a malignant chemical causing cancer while hexane
is also targeted for discontinuation in extraction of oil in human
food applications. (no alternative has probably been found yet).
However, its efficient, if a very expensive way to extract oil
on small scale and the cheapest way to extract oil on a large scale.
And the reason is really because hexane is highly flameable, a heavy
gas accumulating in corners and can't easily be detected. A small
leak in the system would blow the plant sky high - and this happens
all the time. (In the years I have had to do with this, I have
knowledge of two plants in South Africa exploding and taking lives
with it).
On small scale therefore, parching is the least expensive way
to go. Probably to around the 120kg per hour level.
Following this, extrusion presents the most viable avenue to
around the 600kg per hour level. This could yet again be doubled to
around 1,200kg per hour with two extruders and four 300kg/hr
presses. The capital cost is still acceptable and running cost and
maintenance is not too high. This could be expanded upon by using
high quality (and cost) American equipment to levels of around 1.6
tons per hour on a single line and two or three lines may be
installed. bear in mind that while extrusion is a fast way to cook
soy beans, it is also a high energy user.
Steam cooking is often used beyond this level. Its clean
and may use the least expensive energy source such as any biomass to
heat the boilers.
Following the heating of the beans, expelling can take place.
A safe estimate for oil retained in the cake after expelling is
usually around 6 - 8 %. Claims are made for 2-4% by certain
processors. While it may be possible it is not the norm, at least
not with one pass through the press and if pressed more than once,
the viability of the second pressing is normally suspect to say the
least.
Low fat soy oil cake has high protein and when below 3% fat,
it can be processed further into various products for human
consumption such as the TVP's or "textured vegetable proteins" as
well as various other products such as tofu, yoghurts, milk
replacers etc.
Oil expellers:
Small scale oil expellers: Model SGC120 and SGC300.
The SGC120 comes complete with 11kW
motor.
Expeller SGC 120 Datasheet
This economical
cold oil press will provide yields of more than 33% on sunflower
seed and can expel oil from many different types of seeds and
requires only filtration (in the case of sunflower seed) to be
edible.
The SGC120 expeller is now available at a
ridiculous price to enable you to start your own successful
business.
Expeller SGC 300
The SGC300 is in turn, a larger size expeller for small to
medium scale enterprises and uses a 15 to 18.5kW drive which is
included in the price.
Commercial oil expellers - InstaPro Models:
Presses
Electrical can be configured to specific
needs
Model
Power
Capacity
Weight
Dimensions
1000
20 hp / 14.9 kW main drive motor
750-1000 lbs
341-454 kg
7,050 lbs
3,205 kg
Inches 76"H x 57"W x 113"L
cm
193H x
203W x 285L
2000
30 hp / 26 kW main drive motor
3 hp /2.24 kW
krammer drive motor
1,500 - 2,000 lbs 680-909 kg
9,400 lbs 4,273 kg
Inches
90"H x 57"W x 113"L
cm
229H x 203W x 285L
5005
60 hp / 40 kW main drive motor
5 hp / 3.75 kW
krammer drive motor
1 hp / .75 kW variable speed feeder
motor
0.5 hp / 0.37 kW (discharge screw)
4,000-4,400 lbs
1818-2000 kg
14,000 lbs
6,350 kg
Inches
111"H x 78"W x 161"L
cm
239H x 112W x 335L
Press extraction efficiency (output)
Oilseed*
Raw Oil Content %
Raw Protein Content
Oil Removal Efficiency%
Extruding Temperature ° F
Expelled Meal Oil Content %
Expelled Meal Protein Content %
Soybean
18-22
36-40
65-70
300-320
5-8
42-46
Cotton
20-22
20-22
65-70
230-250
5-8
26-30
Canola
35-40
22-26
72-75
250-260
8-13
32-37
Sunflower
35-45
16-22
72-75
240-260
10-13
22-27
*All values used for oil and protein content are expressed in
average ranges. Actual content varies due to variental differences
and growing conditions. Operator management also influences the
quality of the end product. Results when coupling press with
Inst-Pro Extruder.
Model 1000 Press
Features:
Versatile equipment with numerous applications.
Rigid, compact construction.
7.2 to 1 cage diameter ratio.
Ease of operation
Oil filtration option available
Scalable to 24 TPD capacity
Introductory press unit
Cost efficient operation
Low maintenance
Model 2000 Press
Features:
Versatile equipment with numerous applications
7.2 to 1 cage length to cage diameter ratio
Rigid, compact construction
Oil filtration options available
Most popular model
Cost efficient operation
Ease op operation
Oil transfer pump
Krammer unit
Stand and oil tank
Model 5005 Press
Features:
Gear drive with external thrusting housing
8 to 1 cage length to cage diameter ratio
Two oil discharge ports
Modular design for easy maintenance
Stainless steel doors and sheilds
Oil filtration options available
8-10% greater oil extraction
Highest volume output
Improved productivity
Most efficient
Oil transfer pump
Insta-Pro ® Extrusion Technology
Typical Analysis of ExPress ® Soy
Oil
ExPress Soy Oil
National Oil Processors Association
Specifications for Crude Degummed Soybean Oil
FFA:%as oleic
0.34
0.75 max
PV meq/kg
4.22
Anisidine Value
1.06
Chlorophyll, ppm
0.56
1000 max.
Phosphorus, ppm
*300.00
200 max.
Calcium, ppm
33.50
100 max.
Magnesium, ppm
19.80
Iron, mg/kg
1.40
Zinc, mg/kg
0.80
Copper, mg/kg
0.48
Nickel, mg/kg
1.08
Flash Point, °F
300.00
250 min.
Moister and Volatile Matter, %
0.15
0.50 max.
IV
132.03
131
+-
7.5
Viscosity
60.2 Centipoises @ 25° C
Color: Yellow
40.00
Color: Red
3.50
C16:0 Palmitic
10.14
C17:0 Margaric
0.11
C18:0 Stearic
4.20
C18:1 Oleic
24.31
C18:2 Linoleic
51.47
C18:3 Linolenic
8.31
C20:0 Arachidic
0.35
C20:1 Gadoleic
0.19
C22:0 Behenic
0.37
C24:0 Lignoceric
0.12
Other
0.17
* The value represents freshly expressed soybean oil All values are typical analytical results and not garunteed
levels.
Insta-Pro ® Extrusion Technology
Analysis of
ExPress ® Soy Meal
Energy Content (Dry matter basis)
TMEn:
Poultry a
Kcal/Lb.
1484
Kcal/Lb.
3265
ME:
Swineb
1876
4128
NEm
Ruminantsc
Kcal/Lb.
1.08
Kcal/Lb.
2.38
NEg
Ruminants
0.78
1.72
NEL
Dairy
1.03
2.27
ME
Ruminants
1.56
3.43
TDN: Ruminants
88.00%
Neutral Detergent Fiber
11.00%
Acid Detergent Fiber
10.00%
Typical Inclusion Rates
May be used as the major source of protein for all
specie.
Inclusion rate will vary with specie and stage of
production:
Monogastics: Inclusion from 15% to 40% of the complete
diet.
Ruminants: Inclusion up to 25% of the grain mix.
a Zhang et. al, 1993
b KSU, 1998
c Calculated based on NRC Dairy, 1989, Page 9
All values are typical analytical results and not
guaranteed levels.