First step: Sterilization
Sterilization -in the processing of palm oil- are technically done with a steam / water vapor on palm bunches in a Sterilizer equipment in the form of a large autoclave. The purpose of sterilization in the processing or manufacture of these oils are 1) to inactivate the lipolytic enzyme, which can prevent the development of free fatty acids, 2) to facilitate the release of fruit from the bunches, 3) the softening of oil palm fruits, and 5) to coagulate gum / emulsifier to facilitate extracting the oil. Distribution of processing time for sterilization is divided into five sections, namely: 1) air evacuation, 2) time to achieve the required pressure, 3) time for the sterilization of bunches, 4) vaporization of water, and 5) removal, reduction, and reloading. Too longer processing time at the sterilization stage, so there will be much oil is lost (3%) and the palm kernel turn black (dark). When the processing time during the sterilization phase is too short, then the fruit will be difficult to be released from oil palm bunches at the next processing stage, which is threshing.
Step two: Stripping / threshing
The tools used in the processing stage is referred to a stripper (shellers), serves to release the palm fruit from palm bunches by slamming the bunches, so that sometimes this process step is called the dings phase or dings processing stage, with a range of equipment called as stripping/ threshing station. The purpose of the process of stripping or threshing or dings in the processing of palm oil is: 1) to release palm fruit from palm bunches, and the results known as “brondolan (javanese language for the palm fruits)”, 2) palm oil produced from palm oil extraction no longer absorbed by the oil palm bunches so that not to lose efficiency during palm oil processing, and 3) palm bunches does not affect the volume of material in further processing stages. Stripper must be feed with the material (oil palm bunches) continuously in accordance with the capacity of the appliance during this processing stage, because if too many palm bunches at the earlier, so the palm bunches will protect each other, so that there are still palm fruits that have not been released.
Step three: Digestion
This processing stage uses kettles (closed cylindrical tank in a steam jacket, where in the tank there are knives or rods that connect the main shaft, serves to destroy palm fruit that have been separated from the palm bunches). The purpose of digestion stage in the processing of palm oil is: 1) to release palm oil from pericarp, 2) to set up a suitable temperature for the mass of palm oil to be compressed (190 ° C), 3) to reduce the volume of material so that increasing the efficiency of palm oil processing and 4) draining the palm oil that has been released during this processing phase.
In the digester, palm fruit will be destroyed as a result of friction, pressure, and cutting. Palm oil has also begun to be released from palm fruit at this stage of this process. Oil produced during digestion come out through the hole in the bottom of the digester, then be mixed with palm oil resulted from further phase of palm processing oil which is extraction or compression phase.
Step Four: Palm Oil Extraction
In the early stages of this processing, palm fruit must had been crashed and out of the bottom of the digester in the form of palm fruit pulp. The results is then compressed in the compression equipment under digester. Generally, compression equipment used in oil palm processing company is a screw press. Roatation of the screw inside the equipment push the palm fruit pulp in the direction of cone sliding on opposite sides. Palm oil is released out of the palm fruit pulp then passes through the press cage.
Compression with a screw press in processing has the characteristics: 1) working with high pressure where the pressure is derived from the rotation of screw, 2) in the form of screw / helix that spins in container, 3) pressure on the press cake is bigger, because the distance of screw with the wall become less, 4) if the pressure is too heavy, it will result in many broken nut, and 5) this equipment is suitable for palm nut with the small percentage of nut and more percentage of palm fiber or proportion of the nut to palm fruit about 20% fruit.
Step five: Clarification
Clarification on the clarification station -sometimes referred as palm oil refining- in palm oil processing aims to clear up the oil so that palm oil is obtained with the best quality and can be marketed with a good price. The clarification in the palm oil processing industry is the filtration, precipitation, centrifugation, and purification.
Crude palm oil in the form of the mixture from digestion and compression step is flowed toward the sieve vibration (vibrating screen) to be filtered so impurities in the form of coarse fibers can be separated. Crude oil is then stored in the reservoir of crude palm oil (crude oil tank / COT), then heated to a temperature of 95 - 100oC, in order to increase difference in specific gravity between oil, water and sludge so it is very helpful in the process of settling .
Oil from the next COT is flowed into settling tanks (continuous settling tank / clarifier tanks.) Inside the tank, crude oil is separated into oil and sludge as the treatment with the sedimentation principle. Palm oil can still be extracted from the sSludge with certain palm oil processing method such as centrifugation.
Palm oil processing further through the complex stages of purification.
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