|Small Scale Vegetable Oil Extraction (NRI, 1995, 105 p.)|
Oilseeds are the major source of edible oils. The oil-cake remaining after the greater part of the oil has been extracted is a valuable source of protein for animal feeds. Nutritionally, oils provide the calories, vitamins, and essential fatty acids in the human diet in an easily digested form. Oils are used in cooking to enhance the flavour and texture of food. It has been estimated that while 30% of malnourished children in developing countries suffer from a lack of both energy-producing and protein foods, the other 70% suffer from a lack of calories which could be obtained largely from oils and fats. The per caput consumption of fats in tropical Africa is roughly one-quarter of that in North America. Only a small number of developing countries have surpluses of vegetable oils for export. Malaysia and Indonesia export palm oil, the Philippines export coconut oil, and Brazil and Argentina export soy-bean oil. In most developing countries, vegetable oils are in short supply with the rising demand due largely to population growth. The need to import uses up scarce foreign exchange.
Most developing countries have large-scale oilseed processing facilities which are generally located near large towns. Oilseeds grown in rural areas are normally transported to the urban oil mills for processing, but poorly maintained roads and vehicles make the transporting of oilseeds from rural areas to urban oil mills both difficult and costly. Haulage of cooking oil back to rural areas presents the same problems. The high urban demand for vegetable oil leads to shortages in rural areas. Oil that does reach the rural areas is sold at a much higher price than in the large towns.
Oilseeds are grown for cash and subsistence purposes. Local small-scale oilseed processing offers a simple way for rural populations to make oil using their own resources. There are a number of ways in which vegetable oil can be extracted on a small scale from oilseed. Examples of some basic oilseed extraction methods are:
· oil extraction methods using water
· manual methods using kneading
· hand-operated presses
These methods may be used to process up to 100 kg of seed/in and are fully discussed later in this publication. The suitability of each method depends on individual requirements. The process offering the most efficient oil extraction is not always the most suitable option. An oilseed processing venture based on an apparently suitable technology can subsequently fail because it is not suited to the local culture. Success depends on assessing the local conditions which determine the scale of the operation required. These include the availability of power, the amount of seed available, the seed type and the seed/oil price ratio. Equally important are local conditions, the availability of support services, and good management skills. Careful consideration of these local circumstances is essential for the selection of the most suitable oilseed processing operation.
Some of these processes do not require expensive equipment and can be operated at a household level. For example, an individual woman householder processing only a small quantity of seeds per day to provide her family's food needs would probably find that a simple method using water to extract the oil would be suitable. At the other end of the scale, an expeller which requires a substantial capital investment would be more suitable for a dynamic co-operative producing large amounts of seed. Since the investment incurred has to be recovered from the proceeds of the operation, careful financial management is essential.
Many oilseed expelling operations can be run successfully by custom milling. An oilseed processor may extract oil as a service for the oilseed producer in exchange for a portion of the oil and the oil-cake. In this way, cash transactions between the expeller operator and the seed supplier are minimized. In addition, the farmer has a local, assured outlet for his seed, oil-cake to feed his animals, and a substantially improved supply of cooking oil for home consumption. The farmer also has the opportunity to sell surplus oil locally instead of relying only on seed marketing, as a source of cash income. Likewise, the oilseed processor can sell the oil and cake received in payment for the processing service.
Careful financial assessment is necessary to determine whether the operation is able to make an adequate profit after covering all the costs, including interest payments of any loans incurred. All this needs to be done before committing any financial resources.
It must be borne in mind that the advice offered by commercial manufacturers of oilseed processing machinery may be inappropriate as often they will be unable to take all these local considerations into account. Some manufacturers will not have the local knowledge required to help people with the specific operating problems encountered when using unfamiliar new equipment. Sometimes, installed equipment is left unused because the process does not fit into traditional social patterns. Several examples exist of equipment being set up in developing countries and then left unused because the cost of running the equipment could not be met from the proceeds of the operation.
We hope that this publication, written by processing technologists and socio-economists, giving information on technologies available and offering guidance drawn from experience in developing countries world-wide, will assist readers in choosing the most suitable oilseed processing option for a given situation.