VALUE CHAIN #
Supply of seeds/seedlings
The Nigeria Institute for Oil-Palm Research (NIFOR) is the sole supplier of sprouted seeds/seedlings to farmers. The sprouted seeds are sold in imported bags of 500 seeds each. Thus, it costs N15,000 to buy a bag of 500 sprouted seeds (the minimum quantity). Unsold sprouted seeds are sent to the nursery unit for planting and subsequent sales. The seed production unit has the capacity to produce between 5 – 10 million sprouted seeds in a year. Currently, the unit produces sprouted seeds in excess of demand despite operating at about 50% capacity.
Seeds/Seedlings Prices
According to sources in the seed production unit of NIFOR, the actual or market price of the sprouted seed is between N150 – N200, but subsidized by the federal government and sold at N30/seed.
NIFOR supplies sprouted seeds/seedlings to state governments, private individual farmers and large estates. Other sources of seeds/seedlings supply include large scale oil palm estates and companies like Presco Nigeria Plc and Okomu Nigeria Plc., some producers/sellers who produce adulterated seeds and sell them to unsuspecting farmers in the name of NIFOR at less than N30/seed or less than N150/seedlings. Some farmers (especially, those not aware) simply harvest sprouted seeds or seedlings from their farms and plant them. Farmers were asked to identify the sources of supply of seeds/seedlings they planted. Their responses are shown in the graphic below
In Ondo State, about one million oil palm sprouted seeds were imported from Malaysia under the Wealth Creation Agency (WECA) and planted in a central nursery at Agric Village in Ore. The venture however appears very ambitious as farmers are reluctant to buy from the agency at N100/seedling.
Supply Constraints and Challenges
Annual Production Targets
Following the federal government policy in 2003 to increase cultivated oil palm plantations by one million, NIFOR gave the seeds/seedlings unit annual seeds production targets to ensure adequate supply of sprouted seeds. This accounts for the continued excess of supply of sprouted seeds/seedlings by NIFOR.
Availability of Resources
The production of seeds/seedlings is very expensive and time consuming. However, government funding for NIFOR has declined over the years leaving the Institute to struggle through the years.
The situation is compounded by the fact that NIFOR sells at the selling prices fixed by the federal government (i.e. N30/seed and N150/seedling) far below the cost prices. Thus, NIFOR must continue to depend on federal government funding to survive.
Supply of Adulterated Seeds/Seedlings:
To unsuspecting and ignorant farmers at ridiculously very low prices has poses a challenge to the quantity of good quality seeds/seedlings that can be supplied to the market NIFOR has to grapple with unfair competition. https://www.coursehero.com/file/pcj12t2/Supply-of-SeedsSeedlings-The-Nigeria-Institute-for-Oil-Palm-Research-NIFOR-is/
Pegging the planting pattern
When the soil of the plantation has been well cleared by fire, peg out the places where you will plant your seedlings.
To be sure to plant at the right density, you must peg out carefully before planting.
Then you will be sure of having always the same distance between rows and in each row the same distance between oil palms.
To get a good yield, you must plant the oil palms at the right density.
If the oil palms are planted too close together, the roots get in each other’s way, and the leaves do not have enough air and sun: the yield will be low.
If the oil palms are not planted close enough together, each separate tree produces much, but the roots do not use all the soil: the yield per hectare will be low.
How to peg out the planting pattern
Trace lines across the slope and put in your pegs in straight lines;
leave 7.8 meters between rows and 9 metres between pegs.
In this way you can plant 143 oil palms per hectare; this is the best density. Pull out tree stumps and remove fallen trees close to the pegs, because these stumps and trees would interfere with the oil palms.
Planting pattern for a plantation
PLANTING OUT THE OIL PALM SEEDLINGS
One month before planting, dig a hole at each place where you have put a peg.
The hole should be 0.60 metre long and wide, and 0.80 metre deep.
When you are digging the holes, cut any roots that you find in the soil.
Do not mix the soil from above and the soil from below.
A few days later fill in the holes with the earth you have dug out.
At the bottom of the hole, put the soil you have dug out from the top, and at the top put the soil you have dug out from below.
Fill the hole well, so that no saucer shape forms on top.
Lifting the seedlings from the nursery
- The right time to plant is the beginning of the rainy season.
- In this way the young plants can develop their root system before the dry season arrives.
- Choose the biggest and the best-grown seedlings.
- Leave in the nursery any seedlings that are small or badly grown.
- Cut away all the dry leaves and the tip of leaves that are too long.
- Put grease over the cut ends where you have removed leaf tips.
- Tie the leaves together.
- Do not lift the seedlings long before you plant them.
- Lift and plant them in the course of a single day.
- In order to keep a big ball of earth around the roots, lift and plant the palm oil seedlings with a plant setter.
- If you use a Socfin plant setter,place the seedlings after lifting into a wooden box in order to carry them to the plantation.
- If you use a Java plant setter,leave the seedling inside the plant setter when you carry it to the plantation.
- The seedling is tied into the plant setter.
Seedling in wooden box
Make the holes for planting in the plantation, with the plant setter you use for lifting the seedlings from the nursery beds.
Do not make the holes several days before planting.
If you make the holes too long before planting, the rain may wash earth from the sides into the hole, or the sun may dry out the earth on the sides.
The ball of earth around the roots must be level with the soil of the plantation.
The earth must not form a hollow around the crown.
Fill in with earth the space between the sides of the hole and the root ball.
Remove with a little stick all the earth that has fallen on the leaves.
PUTTING WIRE NETTING AROUND SEEDLINGS
Certain animals may eat the young oil palm seedlings. To protect the seedlings, surround them with wire netting.
Leave the wire netting in place for about 18 months.
When you have put your wire netting in place, spread a mulch 20 centimetres thick around the seedlings. This mulch prevents the soil from drying out, and prevents weeds from growing.
Use dry herbage, and spread it 15 to 20 centimetres thick at a distance of 30 to 40 centimetres around the crown.
A few months after planting, apply fertilizers.
The right time to apply fertilizers is near the end of the rainy season.
The recommended dose of fertilizers for each plant is: 250 to 500 grammes of ammonium sulfate and 250 grammes of potassium chloride.
Spread the fertilizers in a ring underneath the longest leaves.
After you have spread the fertilizer, cover it with a little earth. If there is a mulch around the seedlings, remove the mulch before applying the fertilizer. Afterwards spread a fresh mulch of dry herbage.
http://www.fao.org/docrep/006/t0309e/T0309E03.htm
Applying fertilizer
The oil palm needs a lot of mineral salts to form its leaves and fruit clusters.
When the oil palm is young, it needs above all nitrogen.
When the oil palm has begun to produce, it needs a lot of potash.
Potash increases the number of fruit clusters, and makes them bigger.
HOW MUCH FERTILIZER TO APPLY?
Example: Ivory Coast
On plantations (per tree per year)
| Age of oil palm |
Savanna | Forest | ||
| Grammes | Fertilizer | Grammes | Fertilizer | |
| Year of planting | 500 500 |
Ammonium sulfate Potassium chloride |
250 250 |
Ammonium sulfate Potassium chloride |
| 1 year | 750 750 |
Ammonium sulfate Potassium chloride |
500 300 |
Ammonium sulfate Potassium chloride |
| 2 years | 750 750 |
Ammonium sulfate Potassium chloride |
750 to 1 500 | Potassium chloride |
| 3 and 4 years and afterwards | ||||
| 1 000 to 1 500 | Potassium chloride | 750 to 1 500 | Potassium chloride | |
On natural palm groves (per tree per year):
1000 grammes of potassium chloride
Example: Benin
On plantations (per tree per year)
| Age of oil palm | Ammonium sulfate | Potassium chloride |
| Grammes | Grammes | |
| Year of planting | 250 | 200 |
| 1 year | 350 | 200 |
| 2 years | 500 | 500 |
| 3 years | 600 | 750 |
| 4 years | 600 | 1 000 |
http://www.fao.org/docrep/006/t0309e/T0309E04.htm
HARVESTING
Harvesting needs much time and much care, because only those fruit clusters which are cut at the right moment yield a lot of good-quality oil.
You must go through the plantation many times to pick the ripe clusters. A cluster is ripe for harvesting when the fruits begin to turn red, and when 5 or 6 fruits drop to the ground.
If you wait too long before harvesting the clusters, harvesting takes much more time, because you must pick up all the fruits that have dropped to the ground.
The fruits will also yield less oil, and the oil will be of less good quality.
If you do not wait long enough before harvesting the clusters, the fruit will not be ripe enough.
It will be more difficult to separate the fruits from the clusters and the clusters will yield less oil.
The clusters can be cut off with different tools.
For oil palms 4 to 7 years old
Cut the clusters with a chisel.
Slip the chisel between the stem and the leaf; in this way you can cut off the cluster without cutting the leaf below it.
For oil palms 7 to 12 years old
Cut the clusters with a machete.
If the clusters are too high up, climb up the tree by putting your feet on the base of the leaves.
For oil palms older than 12 years
Cut the clusters with a long-armed sickle.
If the clusters are too high up to be cut with the long armed sickle, use bamboo ladders, or else climb up the tree with a belt; you can also wear spiked shoes. Any clusters that have dropped to the ground should be collected in a basket. Fruits that have come loose must also be picked up.
List of Nigerian palm oil company
15 Ajao Avenue, Off Adeniyi Jones, Ikeja, Lagos, Ikeja, Lagos
We supply individuals and large organization with Palm Oil, Natural Honey, Garri (white and yellow), Cocoa, Cassava, Fresh Eggs and other farm products.
O.J&CO SUCCESS VENTURES NIGERIA LTD
Ishiuzo Egbu, Owerri North , Owerri, Imo
O.J&CO SUCCESS VENTURES NIGERIA LTD is a company that sells and delivers good quality of Palm oil to individuals and companies in Nigeria and abroad for export.
Enterprise Asset Leasing Limited
2, Ramat Crescent, Ogudu G.R.A, Kosofe, Lagos
Nosak Group is a diversified business group with interests in key sectors of the Nigerian economy. These include Real Estate, Agriculture, Oil and Gas, Consumables Retailing, Healthcare, Haulage etc.
Plot C34, Nosak Road, Amuwo Odofin Industrial Estate, Amuwo Odofin, Lagos
Nosak Group is a diversified business group with interests in key sectors of the Nigerian economy. These include Real Estate, Agriculture, Oil and Gas, Consumables Retailing, Healthcare, Haulage etc.
JK House 6, Accara Lane, Umuahia, Umuahia, Abia
At Johnny Kelle Farms, we develop the following the ranges of high quality products through the Plantation, Cultivation and Manufacturing and Processing division of the farm.
3B REACH AVENUE OFF OZIZZA ROAD, AFIKPO, AFIKPO NORTH L.G.A., Afikpo, Ebonyi
my company is an aggro-based industry.we are into palm oil processing, palm oil machinery supplies,fisheries; fingerling breeding and supplies, outdoor breeding, table size catfish production, pond etc.
2B Dan Amar Road U/Rimi GRA Kaduna, Kaduna, Kaduna
Suppliers/exporters of Agricultural products like Smoked catfish, Cashew nuts,Ginger,cassava,palm oil.
22B Araromi Street, Off Adigbe Road, Abeokuta South, Ogun State, Nigeria., Abeokuta, Ogun
queensoil ventures offer the very best of palm oil. our price is affordable and our products available at all time of demand we supply to you anywhere in lagos and ogun state. with a ZERO DELIVERY CHARGE.
https://www.businesslist.com.ng/companies/palm-oil
List of Oil Exporters
Presco Plc
Obaretin Estate, Km 22 Benin / Sapele Road, Ikpoba-Okha LGA, Benin City, Edo State, Nigeria
+234 803 413 4444
Presco Plc specializes in the production of palm oil and its various byproducts like palm olein, Palm Stearin, Crude Palm Kernel Oil.
Bettymor Enterprises Limited
120 Dsc Express Way Ovwian, Udu LGA, Warri, Delta State, Nigeria
+234 703 497 3760
Bettymor Enterprises are into the production and exportation of palm oil, rubber, cocoa, coffee, Irish potatoes, onions, cashew nut, soy beans and tropical flower.
Cosmedic Limited
9 Adebiyi Street, Estate Phase I, Magodo, Lagos State, Nigeria
+234 808 214 6486
Cosmedic specialize in exporting palm produce such as Crude Palm Oil, Refined Palm Oil, Palm Kernel Shells
Dijesr Fennimol Limited
8 Dayo Adeniji Street, New Oko Oba, Ifako Ijaiye, Lagos State, Nigeria
+234 808 058 6440
Dijesr Fennimol specialize in the export of palm oil, coconuts, cocoa seeds, Honey.
Mishgides Ventures
389 Abuleado Shoping Complex, Satellite Town, Amuwo-Odofin, Lagos State, Nigeria
08023381337
Mishgides Ventures is a palm oil and coconut oil producing company who also engage in exportation of palm oil.
Zoboe West Africa Ltd
Greenville Estate Badore, Ajah, Lagos State, Nigeria
+234 803 332 9589
Zoboe West Africa is a company dealing on palm oil, kola nuts, ginger, wood charcoal, gum arabic, and honey exportation services.
https://www.finelib.com/business/exporters/agro-allied-products/palm-produce/palm-oil
List of Fabricators Palm Oil Milling Machine in Nigeria
Nigeria Machine tools
1 Taofeek Lawal street off raymond njoku street SW ikoyi,
Lagos 234-461-5432, 234-461-5434
Techo-quip Limited
14-16 olusola Ikare Str,Alake Bus stop, Idimu Ikotun road,Idimu lagos
23408022904222,23408098904222, 23408036292557
www.techoquiplimited.com
Adrosh Engineering Services
1 Sholly Beauty St. Ewedogbon Lasu-Isheri Express way
8023224406
B&T Ventures Nig. Ltd
Ijerusalem B/Stop, Arulogun Road Ojoo- Ibadan
08023501031
Ese Engineering Services
34 Rd., K Close, House 6 Gowon Estate, Egbeda
08023153561
Starron Nig. Ltd
27, Layi Oyekanmi St. Palm-Avenue, Mushin, Lagos
08056380422 08088582228
A.E.H. Technical Metal Works
Mosalasi Yidi Oba Water Works Area, Iwo Osun State
08034988823
O Akins Gen. Co
26, Taye Odinjo Str. Kunola Egbeda Lagos
08023279203
Techo-Quip Ltd.
14 – 16 Olusola Ikaresi, Alake Bustop, Idimu – Ikotun Rd, Idimu, Lagos.
08037126544, 08022904222
Nobex Tech Ltd.
Vic- Morak Street, Nobex Bus Stop, Ikotun/Idimu Rd, Ikotun, Lagos State.
08037133587
Akintech Eng. Com. Ltd
14 Fatai Ayolo Close, Abule Oke, Iyana Iloso B/S, Ogun State / 82 Ipaja Road, Alaguntan B/S Iyana Ipaja Lagos.
8037152302
Octec Technologie Ltd.
196 Oshodi Apapa Expressway Ilasamaja.
08033023349
Fabod Engineering Ltd.
Ibuloko Junction, Idi-Orogbo Area, Ota-Itele Rd, Ota, Ogun State.
08034032296
Hicmann Investments Ltd
229 idimu-Egbeda Rd, Carwash B/Stop, Beside Tbank, Idimu, Lagos State.
08034003725
These firms specialize in fabrication of palm oil milling machine in Nigeria, from palm presses, hoppers, extruder and mills. They also deal in specifications, e.g. Tonnage, power, strength etc… http://the-ahamefulas.com/13-fabricators-of-palm-oil-milling-machine-in-nigeria/
Processing
Palm oil processors of all sizes go through these unit operational stages. They differ in the level of mechanisation of each unit operation and the interconnecting materials transfer mechanisms that make the system batch or continuous. The scale of operations differs at the level of process and product quality control that may be achieved by the method of mechanisation adopted. The technical terms referred to in the diagram above will be described later.
The general flow diagram is as follows:
PALM OIL PROCESSING UNIT OPERATIONS
Harvesting technique and handling effects
In the early stages of fruit formation, the oil content of the fruit is very low. As the fruit approaches maturity the formation of oil increases rapidly to about 50 percent of mesocarp weigh. In a fresh ripe, un-bruised fruit the free fatty acid (FFA) content of the oil is below 0.3 percent. However, in the ripe fruit the exocarp becomes soft and is more easily attacked by lipolytic enzymes, especially at the base when the fruit becomes detached from the bunch. The enzymatic attack results in an increase in the FFA of the oil through hydrolysis. Research has shown that if the fruit is bruised, the FFA in the damaged part of the fruit increases rapidly to 60 percent in an hour. There is therefore great variation in the composition and quality within the bunch, depending on how much the bunch has been bruised.
Harvesting involves the cutting of the bunch from the tree and allowing it to fall to the ground by gravity. Fruits may be damaged in the process of pruning palm fronds to expose the bunch base to facilitate bunch cutting. As the bunch (weighing about 25 kg) falls to the ground the impact bruises the fruit. During loading and unloading of bunches into and out of transport containers there are further opportunities for the fruit to be bruised.
In Africa most bunches are conveyed to the processing site in baskets carried on the head. To dismount the load, the tendency is to dump contents of the basket onto the ground. This results in more bruises. Sometimes trucks and push carts, unable to set bunches down gently, convey the cargo from the villages to the processing site. Again, tumbling the fruit bunches from the carriers is rough, resulting in bruising of the soft exocarp. In any case care should be exercised in handling the fruit to avoid excessive bruising.
One answer to the many ways in which harvesting, transportation and handling of bunches can cause fruit to be damaged is to process the fruit as early as possible after harvest, say within 48 hours. However, the author believes it is better to leave the fruit to ferment for a few days before processing. Connoisseurs of good edible palm oil know that the increased FFA only adds ‘bite’ to the oil flavour. At worst, the high FFA content oil has good laxative effects. The free fatty acid content is not a quality issue for those who consume the crude oil directly, although it is for oil refiners, who have a problem with neutralization of high FFA content palm oil.
Bunch reception
Fresh fruit arrives from the field as bunches or loose fruit. The fresh fruit is normally emptied into wooden boxes suitable for weighing on a scale so that quantities of fruit arriving at the processing site may be checked. Large installations use weighbridges to weigh materials in trucks.
The quality standard achieved is initially dependent on the quality of bunches arriving at the mill. The mill cannot improve upon this quality but can prevent or minimise further deterioration.
The field factors that affect the composition and final quality of palm oil are genetic, age of the tree, agronomic, environmental, harvesting technique, handling and transport. Many of these factors are beyond the control of a small-scale processor. Perhaps some control may be exercised over harvesting technique as well as post-harvest transport and handling.
Threshing (removal of fruit from the bunches)
The fresh fruit bunch consists of fruit embedded in spikelet growing on a main stem. Manual threshing is achieved by cutting the fruit-laden spikelet from the bunch stem with an axe or machete and then separating the fruit from the spikelet by hand. Children and the elderly in the village earn income as casual labourers performing this activity at the factory site.
In a mechanised system a rotating drum or fixed drum equipped with rotary beater bars detach the fruit from the bunch, leaving the spikelet on the stem.
Most small-scale processors do not have the capacity to generate steam for sterilization. Therefore, the threshed fruits are cooked in water. Whole bunches which include spikelet absorb a lot of water in the cooking process. High-pressure steam is more effective in heating bunches without losing much water. Therefore, most small-scale operations thresh bunches before the fruits are cooked, while high-pressure sterilization systems thresh bunches after heating to loosen the fruits.
Small-scale operators use the bunch waste (empty bunches) as cooking fuel. In larger mills the bunch waste is incinerated and the ash, a rich source of potassium, is returned to the plantation as fertilizer.
Sterilization of bunches
Sterilization or cooking means the use of high-temperature wet-heat treatment of loose fruit. Cooking normally uses hot water; sterilization uses pressurized steam. The cooking action serves several purposes.
- Heat treatment destroys oil-splitting enzymes and arrests hydrolysis and autoxidation. For large-scale installations, where bunches are cooked whole, the wet heat weakens the fruit stem and makes it easy to remove the fruit from bunches on shaking or tumbling in the threshing machine.
- Heat helps to solidify proteins in which the oil-bearing cells are microscopically dispersed. The protein solidification (coagulation) allows the oil-bearing cells to come together and flow more easily on application of pressure.
- Fruit cooking weakens the pulp structure, softening it and making it easier to detach the fibrous material and its contents during the digestion process. The high heat is enough to partially disrupt the oil-containing cells in the mesocarp and permits oil to be released more readily.
- The moisture introduced by the steam acts chemically to break down gums and resins. The gums and resins cause the oil to foam during frying. Some of the gums and resins are soluble in water. Others can be made soluble in water, when broken down by wet steam (hydrolysis), so that they can be removed during oil clarification. Starches present in the fruit are hydrolyzed and removed in this way.
- When high-pressure steam is used for sterilization, the heat causes the moisture in the nuts to expand. When the pressure is reduced the contraction of the nut leads to the detachment of the kernel from the shell wall, thus loosening the kernels within their shells. The detachment of the kernel from the shell wall greatly facilitates later nut cracking operations. From the foregoing, it is obvious that sterilization (cooking) is one of the most important operations in oil processing, ensuring the success of several other phases.
- However, during sterilization it is important to ensure evacuation of air from the sterilizer. Air not only acts as a barrier to heat transfer, but oil oxidation increases considerably at high temperatures; hence oxidation risks are high during sterilization. Over-sterilization can also lead to poor bleach ability of the resultant oil. Sterilization is also the chief factor responsible for the discolouration of palm kernels, leading to poor bleach ability of the extracted oil and reduction of the protein value of the press cake.
Fig. 1 Bunch thresher (Centre de Formation Technique Steinmetz-Benin)
Fig. 2 Fruit sterilizer (Centre de Formation Technique Steinmetz-Benin)
Digestion of the fruit
Digestion is the process of releasing the palm oil in the fruit through the rupture or breaking down of the oil-bearing cells. The digester commonly used consists of a steam-heated cylindrical vessel fitted with a central rotating shaft carrying a number of beater (stirring) arms. Through the action of the rotating beater arms the fruit is pounded. Pounding, or digesting the fruit at high temperature, helps to reduce the viscosity of the oil, destroys the fruits’ outer covering (exocarp), and completes the disruption of the oil cells already begun in the sterilization phase. Unfortunately, for reasons related to cost and maintenance, most small-scale digesters do not have the heat insulation and steam injections that help to maintain their contents at elevated temperatures during this operation.
Contamination from iron is greatest during digestion when the highest rate of metal wear is encountered in the milling process. Iron contamination increases the risk of oil oxidation and the onset of oil rancidity.
Pressing (Extracting the palm oil)
There are two distinct methods of extracting oil from the digested material. One system uses mechanical presses and is called the ‘dry’ method. The other called the ‘wet’ method uses hot water to leach out the oil.
In the ‘dry’ method the objective of the extraction stage is to squeeze the oil out of a mixture of oil, moisture, fibre and nuts by applying mechanical pressure on the digested mash. There are a large number of different types of presses but the principle of operation is similar for each. The presses may be designed for batch (small amounts of material operated upon for a time period) or continuous operations.
Batch presses
In batch operations, material is placed in a heavy metal ‘cage’ and a metal plunger is used to press the material. The main differences in batch press designs are as follows: a) the method used to move the plunger and apply the pressure; b) the amount of pressure in the press; and c) the size of the cage.
The plunger can be moved manually or by a motor. The motorised method is faster but more expensive.
Different designs use either a screw thread (spindle press) or a hydraulic system (hydraulic press) to move the plunger. Higher pressures may be attained using the hydraulic system but care should be taken to ensure that poisonous hydraulic fluid does not contact the oil or raw material. Hydraulic fluid can absorb moisture from the air and lose its effectiveness and the plungers wear out and need frequent replacement. Spindle press screw threads are made from hard steel and held by softer steel nuts so that the nuts wear out faster than the screw. These are easier and cheaper to replace than the screw.
The size of the cage varies from 5 kg to 30 kg with an average size of 15 kg. The pressure should be increased gradually to allow time for the oil to escape. If the depth of material is too great, oil will be trapped in the centre. To prevent this, heavy plates’ can be inserted into the raw material. The production rate of batch presses depends on the size of the cage and the time needed to fill, press and empty each batch.
Hydraulic presses are faster than spindle screw types and powered presses are faster than manual types. Some types of manual press require considerable effort to operate and do not alleviate drudgery.
Continuous systems
The early centrifuges and hydraulic presses have now given way to specially designed screw-presses similar to those used for other oilseeds. These consist of a cylindrical perforated cage through which runs a closely fitting screw. Digested fruit is continuously conveyed through the cage towards an outlet restricted by a cone, which creates the pressure to expel the oil through the cage perforations (drilled holes). Oil-bearing cells that are not ruptured in the digester will remain unopened if a hydraulic or centrifugal extraction system is employed. Screw presses, due to the turbulence and kneading action exerted on the fruit mass in the press cage, can effectively break open the unopened oil cells and release more oil. These presses act as an additional digester and are efficient in oil extraction.
Moderate metal wear occurs during the pressing operation, creating a source of iron contamination. The rate of wear depends on the type of press, method of pressing, nut-to-fibre ratio, etc. High pressing pressures are reported to have an adverse effect on the bleach ability and oxidative conservation of the extracted oil.
Clarification and drying of oil
The main point of clarification is to separate the oil from its entrained impurities. The fluid coming out of the press is a mixture of palm oil, water, cell debris, fibrous material and ‘non-oily solids’. Because of the non-oily solids, the mixture is very thick (viscous). Hot water is therefore added to the press output mixture to thin it. The dilution (addition of water) provides a barrier causing the heavy solids to fall to the bottom of the container while the lighter oil droplets flow through the watery mixture to the top when heat is applied to break the emulsion (oil suspended in water with the aid of gums and resins). Water is added in a ratio of 3:1.
The diluted mixture is passed through a screen to remove coarse fibre. The screened mixture is boiled from one or two hours and then allowed to settle by gravity in the large tank so that the palm oil, being lighter than water, will separate and rise to the top. The clear oil is decanted into a reception tank. This clarified oil still contains traces of water and dirt. To prevent increasing FFA through autocatalytic hydrolysis of the oil, the moisture content of the oil must be reduced to 0.15 to 0.25 percent. Re-heating the decanted oil in a cooking pot and carefully skimming off the dried oil from any engrained dirt removes any residual moisture. Continuous clarifiers consist of three compartments to treat the crude mixture, dry decanted oil and hold finished oil in an outer shell as a heat exchanger. (Fig. 8, 9, 10)
Fig. 3 Spindle press (Luapula, Zambia)
Fig. 4 Spindle press (Luapula, Zambia)
Fig. 5 Another model of spindle press (Nova Technologies Ltd., Nigeria)
Fig. 6 Hydraulic press (manual)
The wastewater from the clarifier is drained off into nearby sludge pits dug for the purpose. No further treatment of the sludge is undertaken in small mills. The accumulated sludge is often collected in buckets and used to kill weeds in the processing area.
Oil storage
In large-scale mills the purified and dried oil is transferred to a tank for storage prior to dispatch from the mill. Since the rate of oxidation of the oil increases with the temperature of storage the oil is normally maintained around 50°C, using hot water or low-pressure steam-heating coils, to prevent solidification and fractionation. Iron contamination from the storage tank may occur if the tank is not lined with a suitable protective coating.
Small-scale mills simply pack the dried oil in used petroleum oil drums or plastic drums and store the drums at ambient temperature.
Kernel recovery
The residue from the press consists of a mixture of fibre and palm nuts. The nuts are separated from the fibre by hand in the small-scale operations. The sorted fibre is covered and allowed to heat, using its own internal exothermic reactions, for about two or three days. The fibre is then pressed in spindle presses to recover a second grade (technical) oil that is used normally in soap-making. The nuts are usually dried and sold to other operators who process them into palm kernel oil. The sorting operation is usually reserved for the youth and elders in the village in a deliberate effort to help them earn some income.
Large-scale mills use the recovered fibre and nutshells to fire the steam boilers. The super-heated steam is then used to drive turbines to generate electricity for the mill. For this reason, it makes economic sense to recover the fibre and to shell the palm nuts. In the large-scale kernel recovery process, the nuts contained in the press cake are separated from the fibre in a depericarper. They are then dried and cracked in centrifugal crackers to release the kernels (Fig. 11, 12, 13, 14). The kernels are normally separated from the shells using a combination of winnowing and hydrocyclones. The kernels are then dried in silos to a moisture content of about 7 percent before packing.
During the nut cracking process some of the kernels are broken. The rate of FFA increase is much faster in broken kernels than in whole kernels. Breakage of kernels should therefore be kept as low as possible, given other processing considerations.
Fig. 7 Manual vertical press (O.P.C., Cameroon)
Fig. 8 Motorised horizontal screw press (Centre Songhai, Benin)
Fig. 9 Combined digester and motorised hydraulic press (Technoserve/Cort Engineering, Ghana)
Fig. 10 Flushing extractor (Cort Engineering Services, Ghana)
Summary of Unit operations
| Unit operation | Purpose |
| Fruit fermentation | To loosen fruit base from spikelets and to allow ripening processes to abate |
| Bunch chopping | To facilitate manual removal of fruit |
| Fruit sorting | To remove and sort fruit from spikelets |
| Fruit boiling | To sterilize and stop enzymatic spoilage, coagulate protein and expose microscopic oil cells |
| Fruit digestion | To rupture oil-bearing cells to allow oil flow during extraction while separating fibre from nuts |
| Mash pressing | To release fluid palm oil using applied pressure on ruptured cellular contents |
| Oil purification | To boil mixture of oil and water to remove water-soluble gums and resins in the oil, dry decanted oil by further heating |
| Fibre-nut separation | To separate de-oiled fibre from palm nuts. |
| Second Pressing | To recover residual oil for use as soap stock |
| Nut drying | To sun dry nuts for later cracking |
Fig. 11 Clarifier tank (O.P.C., Cameroon)
Fig. 12 Clarifier tank (Nova Technologies Ltd., Nigeria)
Fig. 13 Oil filter (Faith Engineering Workshop, Nigeria)
Fig. 14 Palm nut cracker (AGRICO, Ghana)
Fig. 15 Palm nut cracker (NOVA, Technologies, Nigeria)
Fig. 16 Palm nut cracker (Ogunoroke Steele Construction Works Ltd, Nigeria)
Fig. 17 Palm nut cracker combined with Kernel/Shell separator (Hormeku Engineering works, Ghana)
Process equipment design and selection criteria
In designing equipment for small-scale oil extraction one of the key factors to consider is the quality required. ‘Quality’ is entirely subjective and depends on the demands of the ultimate consumer. For the edible oil refining industry the most important quality criteria for crude oil are:
- low content of free fatty acids (which are costly to remove during oil refining);
- low content of products of oxidation (which generate off-flavours);
- readily removed colour.
The most critical stages in the processing sequence for a processor seeking to satisfy these criteria are: bunch sterilization as soon as possible after harvest; and effective clarification and drying of the crude oil after extraction.
By contrast, for the domestic consumer of crude palm oil, flavour is the primary quality factor. This is boosted by the fermentation that takes place within the fruit when the bunches are allowed to rest for three or more days after harvesting. Thus sterilization immediately after harvesting is not a crucial consideration. Herbs and spices for flavour are introduced during the oil-drying phase of operations to mask off-flavours. Therefore, rigid process control during oil clarification need not be prescribed or incorporated in the design.
The free fatty acids and the trace tocopherols contained in the crude palm oil after natural fermentation also have a laxative effect, which is desirable for African consumers for whom synthetic substitutes are a luxury. The acidity imparts a ‘bite’ to the oil which some consumers prefer. Thus the quality requirements of one market, leading to certain processing imperatives, may conflict with those of another market.
The traditional manual methods are normally referred to as ‘low technology’ production. The mechanised units are likewise referred to as ‘intermediate technology’ production.
The village traditional method of extracting palm oil involves washing pounded fruit mash in warm water and hand squeezing to separate fibre and nuts from the oil/water mixture. A colander, basket or a vessel with fine perforated holes in the bottom is used to filter out fibre and nuts. The wet mixture is then put on the fire and brought to a vigorous boil. After about one or two hours, depending on the volume of material being boiled, the firewood is taken out and the boiled mixture allowed to cool. Herbs may be added to the mixture at this point just before reducing the heat. On cooling to around blood temperature, a calabash or shallow bowl is used to skim off the palm oil. Because of the large quantities of water used in washing the pulp this is called the ‘wet’ method.
A mechanical improvement, based on the traditional wet method process, is achieved by using a vertical digester with perforated bottom plate (to discharge the aqueous phase) and a side chute for discharging the solid phase components. The arrangement combines digestion, pressing and hot water dilution into one mechanical unit operation.
The ‘dry’ method uses a digester to pound the boiled fruit, which is a considerable labour-saving device. The oil in the digested or pounded pulp is separated in a press that may be manual or mechanical. Motorised mechanical presses are preferred, whether hydraulic or screw type.
Most medium- and large-scale processing operations adopt the ’dry’ method of oil extraction. This is because the fibre and nut shells may immediately use to fire the boiler to generate steam for sterilization and other operations, including electricity generation. If the huge volumes of fibre and shells are not used as boiler fuel, serious environmental pollution problems may result. Too much water in the fibre increases the amount and cost of steam required to dry the fibre. Hence the preference for the dry method in plants handling more than six tonnes FFB per hour.
Processing machinery manufacturers tend to make machines to fit individual processing operations. However, recent developments have been toward the manufacture of integrated machines, combining several process operations such as digestion, pressing and fibre/nut separation into one assembly. It is found that these machines fit into two key process groupings: batch and semi-continuous processes.
Schematic of processing models and associated machinery
NB: NOS = Non -oily solids entrained in oil such as coagulated protein, gums and resins, etc. http://www.fao.org/DOCrEP/005/Y4355E/y4355e04.htm
