The Castor bean plant (Ricinus cummunis) belongs to the family Euphorbiaceae, the spurge family. It is a short-lived perennial, which grows into a tree of eight to ten meters in height. There are annual dwarf types of 0.6m – 1.2m in height.
The leaves are large, usually 2cm – 5cm wide or wider, alternate and palmately divided into 5 – 10 lobes. The leaves of different varieties may be green, purple or red. (Plate 4) The stems may also be green or red. The greenish-yellow flowers, without petals are borne in racemes.
- Uses of Castor Bean
- Hydraulic and brake brake fluids, Paints
- Cold resistant Plastics
- Waxes and polishes
- Soil and Climatic Conditions Required for Castor Production
Castor plants thrive on a wide variety of soils provided they are deep and well drained. They yield optimally in fertile, clayey and sandy loams and are highly sensitive to erosion prone soils. The soil is demanding on soil fertility, though extremely fertile soils are unsuitable as they promote excessive vegetative growth at the expense of seed production. A soil pH 6 – 7 is preferred. Indigenous castor varieties are more tolerant to fairly saline conditions than dwarf castor.
Castor is a crop of the tropical, subtropical and Mediterranean climate zones. In the tropics, it can be cultivated over a wide altitude range with moderate rainfall (600 – 1,200 mm). Frost, heavy rainfall and water logging are not tolerated. Castor grows well when the temperature is moderately high (20° – 30°C) throughout the growing period. An average daily temperature of 28° C is optimal for the production of seeds with high oil content. Low temperatures prolong the time of seedling emergence thereby exposing the seeds to fungal attack. High temperatures of about 40°C during flowering adversely affect the sex ratio resulting in poor seed setting.
- Planting Materials
Seed is the cheapest planting material for propagating castor, and with the exception of the large farm at FCT, Abuja which used imported Brazilian variety, respondents obtained their seed from RMRDC, the Agricultural Development Projects (ADP), All Farmers Association of Nigeria (AFAN) or directly from the wild. Only few respondents reported the use of either fertilizers or herbicides and only Benue reported the use of both. Majority of castor farmers who are mostly smallholder farmers, produce castor with hoe and cutlass; while a few used mechanical equipment such as tractor and implements.
Most of the growers collect their seeds from the wild as these are available in some places in Nigeria. The locally collected seeds belong to three categories, small, medium and large seeds).
The Raw Materials Research and Development Council (RMRDC) is promoting increased production of the crop by distributing castors seeds to farmers across the States in the country and the farmers are recycling these seeds. Another unique feature is the imported variety from Brazil that is being used for production in a large farm in Abuja, FCT.
- Castor Bean Processing
The seeds are carefully separated from any capsule debris and are subsequently decorticated. Traditionally, castor oil is extracted by boiling the crushed seeds in water and skimming off the floating oil. Industrial shelling is done between rollers adjusted to the seed size to ensure that only outer shell is broken. Oil is extracted from the decorticated seeds either by screw press, solvent extraction, pre-press-solvent extraction or extrusion followed by solvent extraction.
During the process of castor oil processing, these seeds must be crushed and pressed with hydraulic or continuous castor oil press at high or low temperature. High temperature hydraulic pressing yields 80 percent of available oil. Further castor oil processing can release much of the remaining oil.
The seed must be hulled after harvesting. Castor oil processing can be done manually by hand or more commonly by castor oil press. Maybe small-scale hand-operated dehullers are your choice. Modification of the oil is achieved by a variety of chemical processes including oxidation, hydrogenation, and thermal treatments to produce products for specific applications. Extracted oil is filtered and the material removed from the oil is fed back into the stream along with fresh material. Materials finally discharged from the castor oil press, called cake, contains 8 to 10 percent oil. It is crushed into a coarse meal, and subjected to solvent extraction with hexane. In the entire process of castor oil processing, castor oil press can also be used for peanuts, beans, sesame, soybean, cottonseed, flax, sunflower seed, coconut, cacao, jatropha seed, tea seed, prickly ash seed, chilli seed, corn germ, and other many kinds of oilseeds plants.
fc 4 castor oil production