Palm Oil: Good or Bad?

 


Borneo tallow Cocoa butter Margarine Shea butter Vegetable shortening. Here are 6 ways that lemons can improve your health. Industry urged towards sustainable farming practices as rising demand drives deforestation". On cooling to around blood temperature, a calabash or shallow bowl is used to skim off the palm oil.

related stories


The downstream stage further includes the actual sale of that product to other businesses, governments or private individuals. The type of end user will vary depending on the finished product. Regardless of the industry involved, the downstream process has direct contact with customers through the finished product.

In the oil and gas industry, the downstream process consists of converting crude oil into other products and then selling those products to customers.

Thus, oil refineries represent structures that operate within the downstream process. However, any kind of plant that processes raw materials may qualify as operating within the downstream stage of production. A company that combines both upstream and downstream processes is an integrated company. Brian Bass has written about accountancy-related topics and accounting trends for "Account Today. Bass hold a master's degree in accounting from the University of Utah.

Skip to main content. Definition of Upstream The upstream stage of the production process involves searching for and extracting raw materials. Examples of Upstream Processes In the petroleum industry, locating underground or underwater oil reserves characterizes the upstream process. Definition of Downstream The downstream stage in the production process involves processing the materials collected during the upstream stage into a finished product.

Examples of Downstream Processes In the oil and gas industry, the downstream process consists of converting crude oil into other products and then selling those products to customers. Salinger; June Engineers Ireland: 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.

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. 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. There are two distinct methods of extracting oil from the digested material. 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.

The main differences in batch press designs are as follows: 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 Fig. 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. 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. 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. The main point of clarification is to separate the oil from its entrained impurities.

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: 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.

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.

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.

In large-scale mills the purified and dried oil is transferred to a tank for storage prior to dispatch from the mill. 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. 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. 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.

To rupture oil-bearing cells to allow oil flow during extraction while separating fibre from nuts. To boil mixture of oil and water to remove water-soluble gums and resins in the oil, dry decanted oil by further heating. In designing equipment for small-scale oil extraction one of the key factors to consider is the quality required.

For the edible oil refining industry the most important quality criteria for crude oil are:. The most critical stages in the processing sequence for a processor seeking to satisfy these criteria are: 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.

Thus the quality requirements of one market, leading to certain processing imperatives, may conflict with those of another market. 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. 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 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. This is because the fibre and nut shells may immediately used 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. It is found that these machines fit into two key process groupings: The extraction of palm oil from boiled palm fruit can be accomplished by handling successive batches of materials or continuously feeding material to the machines.

The batch systems work directly on successive loads of boiled fruit to extract oil in one operation for clarification. The direct screw-press is designed to pound a batch of boiled fruit in the entry section of the machine while exerting pressure on the mashed pulp in another section to expel the palm oil in one operation.

The advantage of the wet system is that it is simple and completely leaches all oil and non-oily solid substances that can be carried in the fluid stream out of the digested mash to give clean and separated nuts and fibre. The aqueous effluent from the vertical digester goes directly to the clarification stage of processing. The amount of water needed to flush the pulp is normally the same as that required for diluting the viscous oil that comes from the mechanical press in preparation for clarification.

An inexperienced operator may use too much hot water to leach out the oil and thus consume unnecessary wood fuel. The emulsified oil loss in the fibre can be substantial if care is not taken to ensure full loading of the digester. Vertical flushing digesters, requiring loading and discharging of a specific amount of material, can thus only be used in a batch operation.

Continuous systems work sequentially, with one operation feeding directly into another, related to the arrangement and timing of machine operations. Careful engineering of unit operations is required to minimise discontinuities in the feeding of one stage into another.

Otherwise some machines have to be stopped periodically for other stations to catch up. When there are discontinuities in the flow of materials between process stations the operations are known as semi-continuous. The dry extraction systems with separate digestion and pressing stations are usually semi-continuous. Once operations have been integrated to attain full continuity the capital investment capacity of small-scale operators has been surpassed, because both machinery and working capital for raw material increases greatly with the increased level of mechanisation.

The dry systems do not need much water for processing, although they have the disadvantage of leaving substantial residual oil in the press cake. The oil content of the press cake can be quite considerable percent , depending on the type of press used and the strength of manual operators. The efficiency with which the various presses can extract oil ranges from 60 to 70 percent for spindle presses, percent for hydraulic presses and percent for the Caltech screw-presses.

The first-pressing oil extraction rates also range from 12 to 15 percent for the spindle-presses, percent for hydraulic presses and percent for the motorised screw-presses. In many instances the first press cake is then sorted to remove the nuts, and the fibre is subsequently subjected to a second pressing to obtain more oil an additional 3 to 4 percent on FFB. The second press oil is generally of lower quality, in terms of free fatty acid content and rancidity. Such low-grade oil is used in soap-making.

Some village processors undertake the traditional hot water washing of the entire press cake immediately after pressing instead of sorting fibre and second pressing. Local manufacturers have developed a wide range of machinery and equipment for processing palm oil and palm kernel to fit any budget. All the relevant unit operational machines can be produced to various degrees of finish and quality in the Sub-Region.

It is the combination of the unit operation into an affordable process chain that distinguishes the manufacturers and their supplies. From traditional technologies that rely solely on manual labour and simple cooking utensils, raising the level of mechanization depends largely on a balance between the quantity of bunches available for processing in a given locality and the money available for investment in machines.

The first consideration should be the availability of raw materials and how to compute the processing scale. Knowing the optimum scale of operations, it is then possible to consider the type of processing techniques. The higher the technology, the more skilful operators will be required to handle the machines. These technical considerations should lead to the equipment selection and examination of the capital investments needed to acquire the necessary machines.

Assume a Village Group decides to plant oil palm and establishes a program to plant a certain number of seedlings each year over a seven-year period. In the third year the first set of trees begin to bear fruit. The community wants to establish a processing mill and they call an expert. How is the estimation made of the size and type of processing unit required by the community? Start by establishing the block of planted areas by year so the age of the trees may be determined.

The oil palm tree begins to bear fruit from the third year and the yield per tree increases progressively with age until it peaks around 20 years. The yield begins to decline from year 25 through 40 when the economic life of the tree ebbs.

Table 3 describes the potential yields of palm fruit bunches in metric tonnes from the planted hectares per year. Estimates in Table 3 are used to calculate the expected annual yield for each annual block.