Processing of oil must start immediately after harvesting to produce high quality oil. Delay in processing causes build up of free fatty acids (F.F.A) in the oil produced and this reduces the quality of the oil. The higher the F.F.A the lower the grade of oil. F.F.A build up in checked by boiling of the palm fruits.
Material:- blender, sterilizer, reheating drum, hydraulic press, clarification drum. Fruits should be delivered to the processing shed immediately after harvesting for processing to commence. Any delay reduces the quality of the oil due F.F.A build up which result in the production of hard oil or rancid oil.
STERILIZATION:- This is accomplished by serious boiling of the palm fruits. Detached or with the bunches. The process should be carried out under 24hours after harvesting of the palm fruits. It serves the following purposes. (1) Stops the formation of F.F.A by denaturing the enzymes responsible.
(2) Makes the fruits soft for pounding or blending.
(3) Kills the germs and microbes that might have followed the fruits from the farm.
(4) Makes the fruits easy to detach from the bunch.
Palm fruits is ready for harvesting when it is ripe and 1-10 fruits are easily detached from the bunch. Harvest immediately. Quarter the bunches by cutting it into 4 vertically. .
Gather all loose fruits and pour into billing chamber, the fruits which has been preheated with the bunch should be brought out and fruits knocked out of the bunches. The fruits should be gathered together and packed into the boiling chamber.
THE BOILING CHAMBER:- made of drum or special metal container for the purpose of boiling palm fruits. The drum should be covered with clean sac and plank to conserve heat in the boiling chamber.
Heat to boiling point for 30minutes to 1hours and then turn to pounding or blending.
POUNDING OR BLENDING:- the local method of carrying out this operation is by using pestle and mortar. But now there are locally fabricated machines that carry out this operation efficiently. The purpose of this operation is to remove the mesocarp of the fruit which has been soften by boiling from the nut, so that the oil can be easily extracted.
The machine blender, fabricated locally is very efficient in carrying out this operation. I don’t think there are people still using pestle and mortar for commercial oil production. The pestle and mortar is only used for oil meant for family consumption. There are people with mobile blenders and they push is like wheelbarrow to where ever the service is required for a token fee. I saw some blenders that can be mounted on motorcycle and transported to where ever the service is required within reasonable time. So the days of using pestle and mortar are gone.
The advantage of the machine blender is that the product is still warm after the operation and may not require reheating before pressing. But if the product of blending is completely cold after the operation, there is need for reheating to facilitate easy removal of oil.
PRESSING:- well blended and boiled fruits are put into the perforated metal container of the hydraulic press. The container looks like basket but it is made of strong perforated metal to allow oil to drain out of the container during pressing. The valve of the hydraulic press is closed and the ram operated to press the oil out. The base of the hydraulic press is filled with container and devices which channels the oil into the collection tank. The valve is opened when pressing is complete. Chaff fibre and kernel knocked out of the basket like container. The second container is put in place for pressing while the former is being refilled. The operation goes on like that until the whole fruit is pressed.
The crude oil extracted by the hydraulic press contains some quantity of sludge which has to be removed. This is done by boiling and skimming. The process is called clarification. The crude oil is poured into drum and heated gently to be hot but not boiling. The pure oil is the removed from the top while to sludge stays at the bottom of the drum. The pure oil collected at this point is poured into another drum on fire to dry all traces of water completely from the oil. This process is called SIMMERING. The oil collected in this process is the pure edible red palm oil. Table ready.
GRADING:- grade A oil otherwise called soft oil contains less that 5% free fatty acids. Grade B oil contains more than% free fatty acids.
Soft oil is of higher quality than hard oil and commands better price in the market. It is used to produce edible fat and coating in tin plating.
To produce soft oil, take the following precautions. (1) Avoid bruising the fruits.
(2) Process fruits immediately after harvesting.
(3) Clean equipment’s before use.
(4) Do not harvest unripe fruits and avoid overripe fruits.
GRADES OF OIL FOR EXPORT
(1) Special grade:- palm oil not exceeding 3% F.F.A and less than 2% by weight of water and other extraneous substances and free from adulteration.
(2) technical grade:- Grade (I) not more than 9% F.F.A
Grade (II) not more than 18% F.F.A
Both the special grade and technical grade are export produce but the special grade commands a higher price. Our next topic is the production of palm kernel oil.