Nowadays, there are about 20 countries in the world producing palm oil. And the main producing countries are Malaysia, Indonesia, and Nigeria. The output of these three countries accounts for 88% of the world's total palm oil production. And since 2004, the total amount of palm oil and palm kernel oil has been more than soybean oil, the world's major edible oil. for the first time. While there exists great difference between palm oil and palm kernel oil. Here we would talk about the palm kernel oil extraction
Mechanical extraction
Mechanical extraction processes are suitable for both small and large capacity operations. The three basic steps in these processes are (a) kernel pre-treatment, (b) screw-pressing, and (c) oil clarification.
Mechanical extraction processes are suitable for both small and large capacity operations. The three basic steps in these processes are (a) kernel pre-treatment, (b) screw-pressing, and (c) oil clarification.
Diagram 2: Mechanical extraction of palm kernel oil.
Line (A) is for direct screw-pressing without kernel pre-treatment;
Line (B) is for partial kernel pre-treatment followed by screw-pressing;
Line C is for complete pre-treatment followed by screw-pressing.
Kernel pre-treatment
Proper kernel pre-treatment is necessary to efficiently extract the oil from the kernels. The feed kernels must firstly be cleaned of foreign materials that may cause damage to the screw oil press, Magnetic separators commonly are installed to remove metal debris, while vibrating screens are used to sieve sand, stones or other undesirable materials.
A swinging hammer grinder, breaker rolls or a combination of both then break the kernels into small fragments. This process increases the surface area of the kernels, thus facilitating flaking. The kernel fragments subsequently are subjected to flaking in a roller mill, revolving at 200-300 rpm. The thickness of kernel cakes is progressively reduced as it travels from the top roller to the bottom. The flakes that leave the bottom nip are from 0.25 to 0.4 mm thick.
The kernel flakes are then conveyed to a stack cooker for steam conditioning, the purpose of which is to:adjust the moisture content of the meal to an optimum level, rupture cell walls (initiated by rolling), reduce viscosity of oil, coagulate the protein in the meal to separate the oil from protein materials.
The important factors are temperature, retention time and moisture content. In the palm kernel, the meals are normally cooked to a moisture content of 3 percent at 104-110°C.
Line (A) is for direct screw-pressing without kernel pre-treatment;
Line (B) is for partial kernel pre-treatment followed by screw-pressing;
Line C is for complete pre-treatment followed by screw-pressing.
Kernel pre-treatment
Proper kernel pre-treatment is necessary to efficiently extract the oil from the kernels. The feed kernels must firstly be cleaned of foreign materials that may cause damage to the screw oil press, Magnetic separators commonly are installed to remove metal debris, while vibrating screens are used to sieve sand, stones or other undesirable materials.
A swinging hammer grinder, breaker rolls or a combination of both then break the kernels into small fragments. This process increases the surface area of the kernels, thus facilitating flaking. The kernel fragments subsequently are subjected to flaking in a roller mill, revolving at 200-300 rpm. The thickness of kernel cakes is progressively reduced as it travels from the top roller to the bottom. The flakes that leave the bottom nip are from 0.25 to 0.4 mm thick.
The kernel flakes are then conveyed to a stack cooker for steam conditioning, the purpose of which is to:adjust the moisture content of the meal to an optimum level, rupture cell walls (initiated by rolling), reduce viscosity of oil, coagulate the protein in the meal to separate the oil from protein materials.
The important factors are temperature, retention time and moisture content. In the palm kernel, the meals are normally cooked to a moisture content of 3 percent at 104-110°C.
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