Palm Wine: Potential Industrial Resource
by Poku Adaa
The milky wine obtained from the oil palm tree, Palm Wine, contains a large quantity of yeast and can undergo fermentation to produce Ethanol. Poku Adaa, a freelance writer, discusses the potential of producing Ethanol and dry yeast from Palm Wine, to provide an alternative commercial outlet for Oil Palm cultivation, other than direct sale of the fruit bunches.Tapping of wine from the oil palm tree has been on occupation for rural folk in many West African countries for many years. The wine has always been used for consumption either in its fresh undiluted form or a crudely distilled form. Recent scientific research evidence reveals that palm wine contains a large quantity of yeast which gives the sap its milky appearance. Besides, fermentation of the wine produces Ethanol, a chemical of enormous industrial and economic importance.
The oil palm to-day no longer depends on nature and on the ingenuity of insects, rodents or wind for the crops propagation and multiplication. Oil palm is now cultivated. Commercially, that is. In Ghana, large, medium and small scale plantations being cultivated are the new vogue in farm ing ventures, second only to fish farming.
In large areas of the country which have suffered severe drought and the ravages of bush fires in recent months, farmers are converting their burnt out cocoa farms to oil palm plantations. In the public sector, the State Farms. Corporation has about 10,500 hectares of oil palm while the State Oil Palm Corporation has over 5000 hectares under cultivation at Kwae in the eastern region. Local investments in agriculture are being channelled towards oil palm farming and currently the interest has been generated in rural population so much that a bundle of 1000 young plants ready for transplanting costs €5,000.00.
At the Oil Palm Research Station at Kusi, also in the eastern region, artificial breeding of oil palm is under experimentation and field trials, involving the sciences of microbiology (tissue culture), plant genetics (cloning and crossing) and Entomology (insect pollinators). At the moment, large plantations and small holdings use high yielding varieties which start to produce 3-4 years after planting compared to 10 years for the wild growing variety.
It is fairly right to predict that within five to ten years, there could be a boom in the industry which would seek for an alternative commercial outlet in addition to sale of kernels and oil for export and local consumption. There is already international and local demand for Ethanol and Yeast and one can foresee economic returns from using oil palm for wine production being higher than could be obtained from direct sale of oil palm fruit bunches.
Palm wine is the milky sap obtained by cutting an incision at the base of the immature bouquet of flowering of the oil palm three. The incision is widened to form a casing, from which the exuding sap is drawn by gravitational suction through a hollow bamboo tubing.
The casing is widened on successive tappings as the inner surface of the casing is sliced off each time and the temperature inside it is raised by smouldering dry raffia torches to reduce the viscosity of the sap and allow it to flow freely through the tiny fibrous ducts of the surrounding plant matter. Abstracting through scientific literature at universities in Ghana and Nigeria, it turned out that the fresh sap from the oil palm tree contains sucrose, glucose, lactic acid, sulphur containing amino acids, vitamin B and large quantities of Yeast. For example, O. Bassil, writing in the West African journal of Biological Chemistry, found that fresh palm wine contains approximately 43 grams of sucrose and 33 grams of glucose per litre of the sap, while the fermented wine contained two types of bacteria and yeast cells.
The oil palm tree has alternating sex life, male and female, flowing alternate in a regular pattern. High yields of palm wine are obtained during the rainy season which coincides with the time of the male flowering. The female flowering is what eventually develop into fruit bunches.
Rural distillation of fermented palm wine takes place constantly to produce local spirits. The wine which is stored for about eight days after being tapped, is boiled in a large closed drum on a wooden fire. A long bamboo or raffia tubing connects the drum through a cold water tank to a delivery unit where the gin is continually drawn off.
The procedure is scientifically crude: the wooden fires afford no temperature control, hence the end product does contain several other chemical substances, mostly aldehydes. The fermentation is not controlled or monitored and because there are no pumping facilities, the cold water tank is only effective during the first few hours of operation. In practice, the water is changed weekly and much of the product is lost with no sufficient condensation of the vapour.
Commercial exploitation of palm wine for Ethanol can be successfully achieved by the setting up of small scale distillation units in rural areas. The basic technology is well developed and only modification of the equipment and method of operation need to be introduced to existing knowledge of palm wine tappers. In the foreseeable future, when solar power becomes operational, heat pumps and solar powered stoves can bring about such type of modification.
In the meantime, a central storage depot can be set up whereby palm wine can be bought and stored and sent to existing distillery units or industries for processing. Ethanol has three types of uses: as a raw material for the drinks industries; as a chemical intermediate for manufacture of other chemicals such as Ethylene and as a future fuel for powering of motor vehicles.
While Ethanol can be produced synthetically, only five developed countries apart from the U.S.A. operate synthetic Ethanol plants with a world wide total capacity of about 450 million gallons per year. On the whole, 75% of world industrial alcohol are produced through fermentation of carbohydrate crops, mainly sugar cane and grain.
Alcohol production from palm wine affords a shift in raw material base that has a great potential for a country like Ghana and an alternative channel for commercial utilisation of the oil palm tree. Apart from the effects of drinking habits on Ethanol demand, the use of Ethanol as an automobile fuel has the greatest potential. It can be blended with gasoline or used as a pure straightforward substitute for powering motor vehicles.
Ethanol is a renewable fuel which has been proven to be easily employed for the running of internal combustion engines. There is no doubt about the limiting availability of petroleum as a fuel. The use of alcohol as a substitute fuel is a distinct possibility of the future and palm wine as one source of alcohol is a potential offspin that merits serious consideration.
The technology of sugar fermentation is well known and understood and its application to produce alcohol might provide an excellent base for the construction of rural industries. There is little information now on the effect of tapping wine on the yield of oil palm fruit bunches.
However, assuming a boom in the acreage of oil palm under cultivation, the choice of using a plantation for alcohol production or for fruit bunch harvesting will be indicated by the economics of the two outlets.
Besides, stem-standing tapping of the wine can be adapted for young plantations while felled-stem tapping can be employed for aged trees that have exhausted their capacity to yield fruit bunches. The rate of tapping can be industrialised using similar techniques that apply to tapping of rubber on estate plantations.
However, this potential can be boosted by lots of agricultural research into the economics of alcohol production from palm wine such as the yield of wine per acre of palm trees and the yield of Ethanol per litre of the wine, which information is unavailable at the present time.
Yeasts are a group of natural microorganisms that are encountered in natural processes of fermentation and in several industrial processes. Thus the distinction is made of bakers' yeast, brewers' yeast, wine yeast, etc.. Large scale commercial fermentation can be carried out to-day which involve controlled fermentation, concentration of the yeast by centrifugation, filtration and pressing to obtain dry yeast which can be packaged for marketing.
The ultimate usage depends, however, on the type of yeast cells extracted and the source of the sugar used for fermentation. Fermentation is the name given to the transformation of sugars to Ethanol due to the action of yeast cells which do that in order to survive and multiply, and this is achievable in the presence of minerals, sulphur, vitamins and nitrogen. All these ingredients are present in palm wine and there is every indication that industrial production of yeast from palm wine is possible, especially yeast for use in bakeries for leavening of dough.
It is pertinent to note, however, that in order to isolate a large quantity of yeast, the production of Ethanol must be suppressed or limited by either the introduction of air (oxygen) or not in the fermentation process. More yeast is produced if the presence of air (oxygen) is curtailed. In rural distillation of palm wine, the fermentation takes place in open containers and more alcohol is produced as a result.
The industrial production of yeast falls into the realm of the developing science called Biotechnology. It is the application of scientific and engineering principles of the processing of organic and inorganic materials by biological agents such as yeast and other plant and animal cells. This branch of science is active in many developed countries and one hopes that in future its benefits will enable the rationalisation of exploiting the resource of the sap from the oil palm tree.
The oil palm tree has fibrous roots which penetrate large tracts of land even to adjacent plants and has the tendency to shade out other crops. It monopolises land and degrades land for many years. Mixed cropping with oil palm is not possible after the first season of fruiting. Hence the maximum utilisation of the trees should be adopted for a long term commercial exploitation of the tree. The potential of using palm wine for Ethanol or yeast production is very significant indeed.
Necessity hath no law. Feigned necessities, imaginary necessities are the greatest cozenage that men can put upon the Providence of God, and make pretences to break known rules.
— Oliver Cromwell to Parliament, September 12, 1654.
