Oil Extraction In Fruits: Ways To Extract Oil From Seeds
The first step in obtaining oil for your Bio-diesel is to remove the seed-coat and husk in a process referred to as Dehulling. In Africa and other developing countries, manual process, where hard objects are used to crack the shells are popular. But machines (dehullers) used in developed countries are being introduced.
Once the nuts are cracked, the oil-bearing seeds are cleaned and dried. Seed cleaning involves the removal of the seed coat and the separation of the chaff. Seed drying can be by placing the seeds under the sun or by heating carefully on the fire for a short while. In the case of using crude means to extract the oil, drying can be followed by warming which ensures more oil yield. Once this is done, the next step is to begin the crucial extraction process.
Method of oil extraction in Africa
Africans are known to derive body creams and cooking oil from nuts through traditional means. One of such means involves roasting palm kernel nuts in dried pans to force out the popular black palm kernel pormade. Others prefers to extract their body cream from boiling coconut juice to separate the oil. Which ever is the case, they both represent sources of very beautiful aroma that are popular in modern cosmetics.
Palm oil and Groundnut oil are very popular dietary sources in Africa. Palm oil can be extracted from fresh palm fruit or from the cooked form. The process of extraction of palm oil from uncooked palm fruit is such an exciting event to behold.
Palm oil extraction represents one of the social aspect of the people of the Niger-delta region of Nigerian. Males, partially naked, usually holds themselves in a boat-like structure called canoe, singing and matching the soft palm fruits, forcing the oil through holes at one end of the canoe.
The palm fruit are usually left to loss water and soften for a long period of time before matching. This method was designed to cater for production of large quantity of Palm oil which are usually fresh with specialised characteristic aroma.
But the case is different when it comes to extraction of oil from groundnut. The Hausa people of northern Nigeria are known to extract groundnut oil. But unlike palm oil, groundnut must be grinded and molded into small balls and fried in groundnut oil squeezed out of the cake to form a delicious snacks (kulikuli).
Methode of Extraction in India
The Indians and Neighbouring people are known for their animal driven mortar and pestles. Oil-bearing seeds are placed in the mortar and grinded by the rotating force of a cattle attached to a pestle walking in a fixed circle. The Indian technique is similar to the rampress device which is rather advance.
use of rampress to extract oil from seeds
Extraction with rampress and expeller are referred to as cold pressing extraction. While it is possible to directly associate expeller with oil extraction, rampress are rather diverse in their uses such that oil is extraction cannot be said to be in the primary. This is because the application of rampress to food preparation is more popular in areas where it is used to force juice out of fruits.
Oil seed rampress is simply a piston inside a cage. With the seeds placed inside the cage, the piston can compress the seeds and force out the oil. Sometimes the operating force of the ram can be from a manual pump lift.
use of expellers to extract oil from seeds
Expelers are the most popular oil extraction Engines. They are designed into small output devices that can cater for small scale extraction.
The oil expeller is a horizontal cylindrical device with a rotating screw, and sealed at one end. The system involves using high pressure to force the seed through the cylinder in the process forcing out oil via small holes in tangential to the direction of motion of the moving seed. Electric motor, Petrol/Diesel engines, or manual means can be used to provide the operating force of the expeller.
Expellers are sometimes fitted with temperature and pressure device which can be adjusted to different sizes of seeds.Unlike traditional means of extraction where the seeds will have to be warm before extraction, expellers can heat the seed contents either by friction or by inbuilt electric heater, or in both ways.
This involves the use of organic chemicals to dissolve out the oil from the seed. The seed must have been grinded and placed in a semipermeable membrane before placing in the solvent extractor. Solvent extraction is fashioned after the "soxhlet extractor apparatus" whereby hexane is most popularly used to extract organic substances which vegetable oil happens to fall within the ambit.
In soxhlet extraction, volatile hexane is vapourise into the top of the the chamber containing materials to be extracted, where the it is condensed and falls down on the bag containing the material, in the process dissolving and carrying the oil. The mixture is carried into the evaporation container When the level of the mixture of hexane and oil in the chamber increases to the arm connected to the evaporation container. A new cycle of evaporation of hexane begins living the oil in the container.
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