Lipid oils: Ximenia

Ximenia americana

Commercial ximenia oil is cold-pressed oil from seed kernels of Ximenia americana, commonly known as sour plum or wild plum. Ximenia oil has attracted keen interest from the international market, mainly due to its anti-aging properties. It has been shown to be an effective treatment for dry skin prone to ageing, since it increases moisture levels, improves the function of sebaceous tissues and improves skin elasticity. It also has anti-inflammatory properties, while the presence of active fatty acids has been shown to improve blood flow in the skin.

Ximenia has a long history of traditional use, particularly in Namibia, although also across much of Southern Africa and other parts of the continent. In north-central Namibia, the fruits of X. caffra var. caffra (large sour plum) are commonly consumed fresh in season (ripe fruits are very soft and difficult to transport and store for long). Seed oil from X. americana is used as a traditional emollient and hair-care product. The oil is extracted by roasting, crushing and boiling the seed kernels, giving a very dark colour and strong smell to traditional ximenia oil (omaadi eemheke in Oshikwanyama, omagadhi gombeeke in Oshindonga). It is also reported that the oil has traditionally been used to soften leather and San people have used the oil to maintain their bows and bow strings. Roots, bark and leaves of ximenia are used in traditional remedies. Some medicinal properties have been documented by academic researchers since the 1930s, and several pharmaceutical and cosmetic preparations have been patented.

Because of its multiple uses, ximenia was included in 2001 in the “pipeline” list of priority species to be promoted by the then recently created Indigenous Fruit Task Team (later to become the Indigenous Plant Task Team – IPTT). Early efforts focussed on potential use of the fruit pulp and seed kernel oil. The unusual ximenia oil, which contains exceptionally long fatty acids for a vegetable oil, was considered commercially interesting, especially for cosmetic applications.

The first trial purchases of decorticated ximenia seeds were conducted from 2001 – 2003 by CRIAA SADC with the support of the IPTT/MAWRD and other developmental donors. The main purpose was to practically test the availability of ximenia kernels from rural community producers, as well as to develop a processing method to produce oil for further research and product development. It soon became evident that rural producers around Eenhana in the Ohangwena Region were very enthusiastic about the potential commercialisation of their ximenia resource, being relatively richly endowed with ximenia trees and using limited amounts of the X. americana fruits and seeds beyond domestic usage of the traditional hair-care oil and its limited local trade. On the product and processing research and development side, it became clear that the traditional dark oil produced by roasting the kernels would not be suitable for eliciting commercial interest and that the more suitable cold-pressing of ximenia kernels was rendered difficult by the very sticky nature of the oil. This processing difficulty was eventually overcome using a hydraulic cage press developed at KAP for marula oil, and the first cold-pressed ximenia oil samples could be made available. In 2003, through the Southern Africa Natural Product Trade Association (SANPROTA), known today as PhytoTrade Africa, an initial 25 kg oil sample was supplied to a French company specialising in sourcing, designing and commercialising vegetable lipid oils for cosmetic and industrial use.

The period from 2004 to 2008 was characterised by both successes and difficulties. A main challenge was to increase volumes to give commercial credibility and confidence to this promising cosmetic ingredient. This was done by optimising oil processing procedures at KAP and also by developing the supply base of Ximenia kernels, a task that was enthusiastically conducted by the emerging Tulongeni Twahangana Producers (TTP), a group formed by a number of communities in 2005 around Eenhana and Epembe with the support of key extension officers of the MAWF (particularly Mr Ephraim Weyulu, now retired and made an honorary member of the IPTT). On the other end of the emerging value chain were the difficulties involved in purifying and standardising the quality of this ‘sticky’ oil to make it acceptable for cosmetic formulation, and built its technical and marketing dossiers as a new ingredient to be promoted on the market – a task successfully performed by the French company Aldivia and negotiated by PhytoTrade Africa for the IPTT and the Namibian stakeholders.

This brief account tries to illustrate the complicated, time-consuming, multi-disciplinary and collaborative efforts that are very often needed to reach the initial commercial stage in the development of a new biodiversity product, in this case kernel oil from X. americana (var. americana) now registered in the market and used as a cosmetic ingredient.

Namibia presently remains the main commercial producer and exporter of X. americana oil. This is certainly an advantage brought about by the pioneering work conducted in Namibia and the strengthening of the ximenia producers of TTP, since May 2012 registered as a cooperative (TTC). However, this also represents a commercial challenge because while interest in this unique oil has constantly increased, annual production fluctuates according to weather conditions in the TTC harvesting area in the Ohangwena and Oshikoto regions.

The genus Ximenia includes eight species. It belongs to the botanical family Olacaceae, which has a pantropical distribution and is found on most continents across the world, in Africa, the Americas and Australasia. The genus was named in honour of a Spanish monk, Francisco Ximenez, who wrote about the plants of Mexico in the 17th Century. Ximenias are drought-resistant, spiny shrubs. Their fruiting is largely dependent on rainfall and other weather conditions. In Namibia, botanists recognise two species, one with a single variety and the other with two varieties:

  • Ximenia americana var. americana, the species that is currently commercialised. It is most abundant in the current TTC area (Ohangwena and Oshikoto regions).
  • Ximenia caffra var. caffra, the fruit of which is commonly eaten. The oil of this species could prove to be commercially interesting as well, but it is different to the oil of X. americana.
  • Ximenia caffra var. natalensis, which is the least abundant subspecies in Namibia and is only rarely found in the far north-east of the country.

However, previously, an additional variety of X. americana – var. microphylla – was also thought to occur in Namibia. In fact, it was regarded as the more common of the two varieties. This project found that there did appear to be two distinct forms of the species, based on their different general appearance, fruit size and seed oil composition. In the dry Kunene Region, ximenia shrubs are mostly found along watercourses, but in drought years barely any fruits can be found. The large sour plum (X. caffra var. caffra) is commonly eaten, while X. americana is reserved for making the traditional oil used as a skin ointment. The variety occurring there was identified as X. americana microphylla, which presented an oil composition slightly different from the variety americana, the specifications of which is presently used in the international cosmetic trade. Kunene inhabitants to some extent harvest ximenia for their own use, but the resource is not very abundant. It is discussed below, but note that it could prove to be just a geographic variation of var. americana rather than a distinct variety.

  • Ximenia americana var. microphylla, also used traditionally for making oil, but the oil composition is slightly different from the variety that is currently commercialised. This variety is more dominant in the north-eastern and north-western regions of Namibia.

Although ximenia shrubs/trees are found in a wide area in the northern half of Namibia, from the Kunene Region to the Zambezi Region (formerly Caprivi) and down to parts of the Otjozondjupa Region, their abundance, species and varietal distribution varies between regions and locations.

In the Kavango and West Zambezi Regions, the ximenia shrubs are not associated with a particular vegetation type and occur sporadically throughout the various woodlands and shrublands. X. americana var. microphylla is generally more abundant than the other americana variety and X. caffra appears far less abundant.

Although the density of shrubs per hectare in some conservancy and community Forest areas was found to be similar to the prime harvesting area of TTC in the Ohangwena Region, it was observed that the fruiting productivity of the shrubs was very poor.

This was partly the result of frosts, to which ximenia shrubs are sensitive, but also because of the direct impact of veld fires that are recurrent and widespread in these Regions. With the poor quality of shrubs in these Regions, commercial harvesting for community income generation does not seem a viable option at present.

In the North-central Regions where ximenia is generically known as Eemheke or Eembeke, the abundance of ximenia shrubs varies greatly. The thorny tree is mostly found on communal land in areas that are less populated. In the more densely human populated areas, the ximenia resource has greatly reduced over the years, most probably due to the clearing of land, deforestation and grazing by domestic animals.

In some places ximenia has almost completely disappeared. This greatly contrasts with the TTC harvesting area in the Ohangwena and Oshikoto regions where ximenia is abundant, particularly in an area stretching from around Ondobe-Eenhana down to Ohepi and Omuthiya-Omuntele. It is in these areas that the variety X. americana americana is by far the dominant variety compared to the other ximenia subspecies. Surprisingly, ximenia is rarely found further east towards Okongo.

Although the distribution pattern of ximenia is patchy, high densities of shrubs above 40 per ha (up to 140 per ha) have been counted in localised pockets that form the main harvesting areas, varying from less than 2 km to 7 km in diameter. Harvesters’ estimates of the age of some of the larger trees ranged between 40 and 70 years, and young trees start producing a substantial fruit harvest after 4–10 years. Large numbers of seedlings and small plants of ximenia species have been observed, indicating that recruitment is taking place in the harvesting areas, although the seedlings are often eaten by goats.

However, ximenia shrubs are still felled for building poles, brush wood fencing, and clearing land, which represents a threat to the resource. This could potentially be counterbalanced by the new value given to the shrubs/trees by the commercialisation of ximenia products.

In the longer term, propagation of ximenia trees has the potential to increase harvesting volumes and reduce the present harvesting effort of collecting ximenia fruits from distant trees that need to be visited regularly throughout the fruiting season. Propagation also seems a necessity to counteract bad harvesting years, which make supply unreliable and are thus currently a threat to commercialisation of the resource.

Ximenia fruits are usually harvested from the ground under trees after they ripen and fall, which generally takes place from December to February. Harvesters carry the fruit to their homesteads, where they are left to dry and are then stored. Decortication generally takes place later in the year, from June/July, after cultivated crops have been harvested and people have more time. Dried fruits are coarsely de-pulped before the nuts are cracked. They are commonly placed on a stone or hard surface and cracked carefully with a stick, to ensure that the kernel can be taken out in one piece. At the request of the ximenia producers, some efforts have been made to find ways to mechanise this process.

Ximenia americana only has a limited traditional use, and is mostly found in the wild on open communal lands or in community forests, less commonly on peoples’ farms. The communities living in an area, therefore, all have access to the resource. Ximenia is currently only harvested commercially in the Ohangwena and Oshikoto regions, and the ximenia harvesters are organised by TTC, which was provisionally registered with the Division of Cooperatives in the MAWRD in May 2012. TTC currently has 12 associations, which are in the process of becoming fully functional. Each association has its own constitution, bookkeeping and administration system and a Management and Supervisory Committee, members of which are elected at the AGM. The associations also each elect four representatives to attend the TTC AGM, where the cooperative discusses main issues and resolutions, and a Board and Supervisory Committee are elected.

TTC membership is open to men and women alike, but the large majority of members are women. At present there are 809 registered members, of which only 13, less than 2%, are men. This is mostly because trees and tree products are traditionally the domain of women. All ximenia kernels supplied by TTP/ TTC thus far have been sold through CRIAA SADC. The seeds are transported to Windhoek, where they are processed into crude ximenia oil at the KAP. From there the bulk of the oil is sold as a cosmetic ingredient to export markets. Because CRIAA SADC and KAP are not-for-gain organisations, it has provided these processing and marketing services on a cost recovery basis. In the not-too-distant future, TTC is likely to open its own processing facility and at that point CRIAA SA-DC will facilitate the process of capacity building and technology transfer.

Traditional ximenia oil can be found, with other indigenous plant products, in open markets throughout the north-central regions of Namibia and further south in the urban centres. This informal trade and the local trade in its area of production have not been quantified. Although it is probably not marginal in terms of the overall volume of oil produced and traded, it remains very limited in providing a substantial income to a large number of occasional harvesters and home-based traditional oil producers.

Ximenia oil, either in its traditional or cold-pressed form, has been incorporated in a few local cosmetic products manufactured in Namibia by SMEs for local consumers. However, the overall volume of oil used has so far remained tiny. There are certainly avenues for growing Namibian demand for such products, starting by improving awareness of indigenous products and their benefits, but local demand will always be constrained by the small size of the domestic Namibian market.

The main outlet for the sizable volumes of coldpressed ximenia oil produced in Namibia is through exports. Namibia has thus far retained its position as the leading exporter of X. americana oil, not only in Southern Africa but worldwide. Over the past six years (since 2008 when the export trade started to become firmer) over 17.5 tonnes of ximenia oil has been exported, representing an average of nearly three tonnes of oil per year. It must be noted that two of these six years were in very poor harvesting years, where fruiting was seriously affected by either frost or drought. Nevertheless, during these 6 years, nearly 70 tonnes of X. americana kernels were produced by the TTC harvesters, an average of 11.5 tonnes per year with considerable inter-annual variation. Consequently, annual income to producers of the kernels varied considerably from a low N$140 per producer in the very poor season of 2012 (only 57 producers could harvest) to N$626 per producer in the bumper 2008 season (with 363 producers). Nevertheless, TTC membership has significantly increased over the past few years, despite the adverse climatic conditions that have periodically affected ximenia fruiting.

These income levels may rightly look modest in absolute terms, but they represent very substantial cash income for rural producers, who are mainly women and single heads of households, for a seasonal parttime activity and where remunerated work opportunities are scarce. The export market for ximenia oil is still undeveloped, and has great potential for expansion providing that supply and production can be scaled up. Due to the occurrence of poor harvesting years, meeting market demand has been a challenge, making potentially new customers cautious about making substantial investments in product development and marketing. The potential for growth is based on the unique quality of ximenia oil, which is appreciated by the cosmetic industry; the ethical sourcing of the raw material; the history of traditional use rooted in Africa; and the efficacy of the ingredient backed by strong scientific evidence.

Ximenia americana kernel oil is non-drying and characterised by a high content of long-chain mono-unsaturated fatty acids. The fatty acid profile is unique, and the long-chain fatty acids have been shown to have bioactive properties. Patents and published literature refer to anti-inflammatory properties, improved cutaneous blood microcirculation, regeneration of dry skin prone to senescence (anti-aging) and improved hair growth (improving the functioning of sebaceous tissues). Besides being used in skin and hair-care preparations, ximenia oil also has a history of use in various medicinal applications such as the treatment of sores and cuts.

Currently ximenia oil is exported to Europe as semiprocessed oil (crude and decanted) and is further purified and standardised into a pure-grade oil that fulfils the required quality standards for inclusion in cosmetic formulations. This process is necessary to meet industry standards and specific customer requirements. The end market for ximenia oil and products that contain it is relatively niche and generally of higher value, primarily targeting consumers who seek natural, organic and efficacious products, and those who are interested in ethical trade. The oil is found in formulation with other ingredients, and as pure oil for use on skin and hair. The number of available products that contain the oil has increased over the past few years, reflecting an overall increasing demand for speciality natural oils.

Cosmetic and personal care brands that currently use ximenia oil in their products include The Body Shop, Melvita, Aromatherapy Associates and Louise Galvin. Product ranges within these brands include skincare, bath and body, anti-aging, and hair-care. In order to market ximenia oil as an active cosmetic ingredient, robust scientific evidence and strong customer communication is needed. This is particularly relevant to a product that is competing against other active cosmetic ingredients which may be sold at lower prices.

However, a number of additional challenges remain to be addressed:

  • Increasing volumes of production is essential to meet rising market demand and reassure customers that the capacity to supply the cosmetic ingredient is reliable. The up-scaling has to be done while keeping the excellent credentials of the Namibian ximenia supply chain intact; quality, traceability, community-trade, ethical sourcing etc. This will be essential for improving the benefits to primary producers and ensuring the sustainability of the TTC producers’ organisation.
  • Ximenia oil is unusual, and difficult to process and purify. Conventional technologies used for processing and filtering other seed oils have, thus far, proved inappropriate with this very ‘sticky’ oil.

Solving these difficulties for application in Namibia would be an important step forward, but such investment might not be proportionate to the relatively small volume that has been produced thus far.

The emerging commercial success of this INP is based on a combination of strong features. Ximenia oil is a new and unique ingredient, with proven efficacy, that has been supplied according to the quality standards required by cosmetic manufacturers.

It remains positioned in niche markets that recognise efficacy and the values of ethical trading, African sourcing, and community benefits consistent with the new Access and Benefit Sharing (ABS) norms.

The success is also based on the development of a robust supply chain of raw materials (ximenia kernels) bringing direct financial benefits to the harvestersproducers that are well organised in a cooperative.

This would not have been possible without their motivation, traditional knowledge and careful utilisation of the resource, as well as the collaborative work of a number of dedicated stakeholders, public and private, profit-making and non-profit.

Up-scaling volumes of ximenia oil without compromising its quality and credentials remains a priority so as to improve the income to, and the number of, primary producers benefiting; to strengthen the TTC cooperative; and to develop and diversify the markets for this unique oil.

Annual harvests in any particular producing area will remain unpredictable due to weather conditions, and to ensure the reliability of the supply to the market, different options will have to be explored, which may be complementary.

This includes expanding the supply from other regions in Namibia and Southern Africa, incorporating oil from other ximenia species. (provided the varying composition of the oils can meet industry specifications), and building a strategic stock of oil to supplement poor harvesting years.

Moving up the value chain so as to capture a greater part of the end value of the ingredient in Namibia will remain an important objective that needs to be carefully planned and implemented.

The development of a TTC facility for storage and processing in Eenhana is planned, whereby current processing technology will be transferred. Further technology and processing improvements will need to be tested before they can be adopted.

The relevance of ximenia trees in the promotion of agroforestry systems should not be underestimated. Propagation of ximenia through seedlings produced in nurseries could also be an important step forward with regard to long-term sustainability of the resource, market and income to producers.