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| Palm |
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| 251 De Smet refineries are processing palm oil Origin Palm oil comes from de pulp of the fruit of the palm tree. A large range of palm trees (Elais, Gui-neensis) are available in West African countries (between 16° north latitude and 12° south latitude), in Indonesia, Malaysia, Sumatra, Brazil, ... The palm tree requires a lot of wa  ter and light.The classical palm tree has a height of about 10 meters, but it can go up to 30 in some cases. The trunk has a diameter of 60 to 80 cm; till the age of 12-14 years, the trunk remains covered by stumps of leaves that have fallen or have been cut. By the age of 20, the trunk is smooth on nearly the full length except at the basis and on top close to foliar crown. Today thanks to cloning, we obtain much smaller trees, which will facilitate a lot the collection of bunches. The palm tree begins to bear fruit at the age of 4 to 6 years. The fruits grow in a bunch, which is of the size of a human head for young tree but the size of a large pumpkin later. In every bunch, more than hundred fruits are enclosed, and each fruit is of the size of a pruim. Normally, a palm tree produces 5 to 15 bunches per year. The number of produced bunches decreases with the age but the size of the bunch increases. An adult palm tree may produce up to 100 kgs of bunches per year. The average weight is between 15 and 25 kg; the mature bunch contains 50 to 75% of fruits and 25 to 50% of stalks or empty bunch of the total weight. The bunches must be collected from the tree when they are mature. A mature bunch is the one where approx. twenty fruits can easily be removed by just a finger push. In parallel to this method, one can observe at the bottom of the tree a few fruits (about 5) naturally fallen. When falling, the bunch throws away all mature fruits; those are very rich in oil and have to be collected separately and transported in a basket till the closest reception and weighing post. Transport and collect of the bunches and fruits has to be fast (preferably less than 24 hours) and a lot of care has to be taken when handling the fruits as every injury to a fruit is the start of acidification of the oil. As soon arrived at the palm mill, the bunches will be sterilised to stop the acidification increase observed in the oil.  Cutting unmature bunch results irremediably in a big loss of oil. On the contrary, bunches with over-mature fruits give a very acid oil which results in loss of fatty acids and of oil in glycerine form that occurs during decantation.To have a homogeneous collection is even more complicated with young trees. During the two first production years, maturation of fruits is very irregular and the above-described method of maturation estimation cannot be used. The crop requires approximately 25 mandays per year and per hectare. We can admit that a man per 4 to 6 ha. is sufficient for crop and all maintenance works. The fruits have the form of the egg with a sharp head at the bottom part (apex). The colour passes from dark blue to orange during maturation. The pericarp of the fruit is composed of an external hull (epicarp) and a pulp made of oily fibres (35 to85% of the fruit weight) containing 40 to 60% of palm oil and 35 to 45% of water. The pulp surrounds a ligneous shell, which contains one or more very hard kernels - palm kernels - which contains about 45 to 50% of palm kernel oil. The empty bunches or stalks are burned to produce steam. Palm oil The palm oil is extracted from the pulp of the palm fruits following the next steps : - sterilisation of bunch - separation of fruit from bunch - heating and humidification of fruits in digester - separation of the oil by centrifugation or pressing - separation and drying of fibres and of palm kernels in a rotary drum - cracking of the nut and separation of the palm kernels either on basis of differences in density or by hydrocyclones Composition IPalm oil has a reddish colour due to carotene and remains liquid at tropical temperatures but in our countries, it takes the form of butter of yellow-orange colour. The palm oil obtained from rancid fruits and not sterilised has an acidity that may rise up to 50%; it will be used for soap. The usual palm oil acidity today is ranging from 3 to 5%. It contains mainly approx.:
Some PORAM standard specifications for processed palm oil
End uses
Process Dry pretreatment Crude oil contains a small amount of phospholipids and other impurities. The complete elimination of these is a requisite if one is to obtain a good final product. A small quantity of concentrated phosphoric acid is generally added to the oil to serve this purpose. This acid attacks the hydratable, the non-hydratable phospholipids and other compounds including the heavy metals contained in the crude oil. Sedimentation from oils treated with phosphoric acid is very low and separation can be done by filtration in the bleaching plant as a cheap alternative to the centrifugal operation otherwise required. Bleaching In the case of physical refining, bleaching-filtration ensures also final purification of oil thanks to complete elimination of residual gums, phosphatides and all undesirable matter precipitated in pre-treatment. In the case of palm oil, the bleaching carried at low temperature has a partial decoloration effect. Effective bleaching for this oil is carried out during deodorisation-neutralisation at high temperature and is called "heat bleach". The pre-treated oil, after addition of phosphoric acid , enters in contact with activated bleaching earth. After contacting, the mixture is sent under vacuum where live steam injection helps to contact the earth and the oil particles. The oil/earth mixture is then filtered in hermetic filters for a perfect handling. Deodorising For palm oil in physical refining we can present some typical operating parameters:
The improved deodorisation technology has led to a perfect overall refined oil quality: -Low residual FFA and high oxidative stability -Light color, bland odor and taste -Low trans and polymeric triglyceride content Furthermore we are perfectly in control of the removal of minor components: -Adjustable process conditions -Limited thermal/oxidative degradation. Hydrogenation Oil quality required for the hydrogenation
Interesterification Interesterification is used to :
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