Taste and smell are the two most sensitive human senses. The nose can often detect and distinguish odours at a level which even modern instrumentation is hard pressed to achieve. The natural world - especially that of higher plants - provides a multitude of flavours and fragrances, either directly or indirectly, which impinge upon these senses. Over the course of time, and with the benefit of many thousands of species of plants from which to produce them, countless numbers of such flavours and fragrances have found their way via essential oils into everyday life: into foods and drinks and confectionery items; into products for personal use such as perfumes, deodorants, shampoos, bath lotions, toilet soaps, toothpastes and mouth washes; into pharmaceutical preparations where flavours are added to make the product more appealing or to mask the taste of less agreeable ones; into items used about the house or office or in industry such as air fresheners, laundry soaps, detergents, cleaning agents and the like; into tobacco products; the list is endless.
In 1985, LAWRENCE estimated total world production of essential oils to be approximately 36,500 tonnes. (This figure excludes turpentine, which in 1985 would have been around 250,000 tonnes; see TURPENTINE, this report.) Levels of production were given for 168 individual oils; a further 62 oils were listed for which estimates could not be provided. Production ranged from the large-volume orange oil (ca 12,000 tonnes) to those with less than one tonne.
More recently, the same author (LAWRENCE, 1993) listed the world's top 20 essential oils in volume terms (again, excluding turpentine). Orange oil production was estimated at 26,000 tonnes (valued at US$58.5 million). Cornmint (Mentha arvensis) and eucalyptus oil (cineole-type) were placed second and third, respectively, with around 4,000 tonnes each. Patchouli was 20th, with just under 600 tonnes production. In total, the top 20 oils amounted to almost 56,000 tonnes valued at US$340 million.
VERLET (1993) has given a slightly lower estimate of world production of "volatile oils": approximately 45,000 tonnes. Of this, about 65 percent is estimated to come from perennial woody plants. About 55 percent of world production (in value terms) comes from 25 developing countries, the most important of which are the People's Republic of China, Brazil, Indonesia and India.
Such figures are quoted to give an indication of the scale and scope of the industry. The number of plant species which are involved is impossible to estimate accurately but must reach several hundreds for those oils which are traded and many more for those which are produced and used locally. They are distributed amongst numerous botanical families and encompass higher and lower plants, gymnosperms and angiosperms, mono- and di-cotyledons, annuals and perennials, wild and cultivated sources. Thousands more species have yielded volatile oils in the course of searching for new oils but, for one reason or another, (poor yields, poor quality, unfavourable economics, poor markets) have never reached the point of commercial exploitation.
Before the advent of synthetics and the production of certain flavours and fragrances from petrochemicals, virtually all such materials were obtained from plant sources. A few were obtained from animals. Even today, the building blocks of many synthetic compounds are derived from plants. Turpentine obtained from pine trees is the prime example of this: alpha- and beta-pinene have no direct flavour and fragrance use themselves, but are isolated from suitable species of Pinus and converted into derivatives with a wide range of flavour and fragrance applications.
Other plants, too, yield essential oils which are used as sources of chemical isolates for derivative manufacture. Chinese and Brazilian sassafras oils from Cinnamomum camphora and Ocotea pretiosa, respectively, are both sources of safrole, which is used to manufacture heliotropin, a valuable flavour and fragrance compound. C. camphora is also a source of natural camphor.
Rosewood oil was once an important source of linalool, an aroma chemical in its own right but also a precursor for other fragrance compounds. Although cheaper sources of linalool are now utilized (still of plant origin), rosewood still finds favour as a whole oil for perfumery use. Sandalwood oil, too, is prized in perfumery and the whole oil gives an aroma which synthetic substitutes cannot match. Lemon-like citral is obtained from Litsea cubeba.
Eucalyptus oils are used in whole form for perfumery use; in refined form as flavour and fragrance products; or as raw materials for the isolation of cineole or citrinellal (depending on the species of Eucalyptus which is utilized). Cedarwood oils are also used both in whole form and as sources of aroma chemicals.
Some odoriferous materials are obtained, and used, in a form other than an oil. The best grades of olibanum (frankincense) are chewed for their pleasant flavour, while others are burnt and employed as incense in religious ceremonies or about the house.
All of the oils or resins referred to above are employed today as flavour or fragrance materials and form the basis of this report. They all have established markets but offer potential for increased or improved production, sometimes from plant sources which are alternatives to existing ones. They are chosen to illustrate the diversity of natural flavours and fragrances and the sorts of opportunities (and constraints) which exist. Many others might have been used.
Some, such as frankincense and myrrh, have been used for thousands of years. Others such as Litsea cubeba and Cedrus deodara oils have become articles of commerce more recently, in the last forty years. The plants from which they are obtained come from a variety of ecological zones: the moist rainforests of South America; the semi-arid regions of Africa; the more temperate areas of North America; the mountainous regions of Asia; and many others. They range from the slow-growing sandal tree to the fast-growing eucalypts.
Basic data on the plants described in this report are given below:
|Genus||Family||Main producing regions||Main applications|
|Piper||Piperaceae||Latin America||Chemical isolates|
(both via chemical isolates)
The format within which each oil or resin is discussed is structured so as to highlight a number of points:
A selected bibliography is appended for each oil/resin to enable those who wish to explore the subject in more detail to do so.- its uses;
- present (and, where possible, predicted) supply and demand, including
national and international quality criteria and prices;
- plant sources, including the variability in oil yields and quality that may
occur within natural populations, and the effects, possibly harmful,
that oil production may have had on the resource;
- the type of harvesting and primary processing methods employed;
- the nature of any value-added processing;
- other uses to which the plant is, or could be, put;
- and the developmental potential of the oil, with an indication of some
of the research needs necessary to maximize the social and
economic benefits which are sought.
Some importance has been attached in the report to providing an indication of markets for the oils or resins and past and present supply sources. It is a mistake, often made by researchers and others, to have no thought for which market the product of one's endeavour is most likely to succeed in or the opportunities or constraints that may exist for its development. If such considerations are given, they are usually relegated to second place while technical matters are attended to.
Essential oil production is no different from any other agricultural-based industry. Sustainable production is dependent upon it being remunerative to the producer and at least as attractive as other options that are open to him. This means that there needs to be a reasonable market for the product. Development will not follow spontaneously from the enthusiasm of researchers, no matter how well-intentioned this is (COPPEN and GREEN, 1993).
One misconception is that there are particular opportunities for new perfumery oils, previously unknown in trade. The reality is that the generally conservative nature of the essential oils industry and the uncertainties in supply of such oils from origin (both in terms of quantity and quality) make the production of completely new oils something that has only a small chance of success.
Of more likely success is the production of:
(b) large-volume oils to serve as alternative sources of chemical
isolates to existing ones.
One example of the latter approach (which is discussed in this report) is the potential use of previously unexploited Piper spp. as sources of safrole. Success in such a venture will bring with it environmental benefits as well as the provision of income-earning opportunities to those who take it up.
Over the past decade, as has been remarked elsewhere (GREEN and HONE, 1992), there have been many initiatives within developing countries to establish new essential oil industries. Unfortunately, the number of failures has exceeded the successes. The former have frequently arisen from basic mistakes: hasty, inappropriate selection of planting stock; misreading of markets and prospects in the face of the known competition; miscalculation of returns against alternative crop options in the investment area; and poor marketing of the product.
An important factor in those developments which have succeeded is the degree of local commitment to the venture which has been made by the primary raw material producers. The attitudes and motivations of the prospective farmers to essential oil production need to be understood and modified if necessary to assist in the development. Where harvesting of wild trees or plants is practised which threatens the survival of the species or the maintenance of biodiversity, then alternative, sustainable options must be put forward to the people whose livelihoods may depend on it. Enforced regulation by legislation is not the answer.
Having established that there is a market for a particular flavour or fragrance (whether domestic or international) and an opportunity for new or improved production, what action is necessary to put these ideas into practice? One approach to the problem in some parts of the world is the development of agroforestry systems, involving trees and a mix of food and cash crops. The cash crops might be essential oil-bearing plants but must be carefully selected on the basis of known demand rather than on fanciful ideas of exotic natural oils inevitably finding a market in the environmentally-conscious world.
Selection of tree crops such as Cinnamomum, Piper and Eucalyptus, which can be harvested under a coppice system of management, offers opportunities for development. Some or all of the research needs enumerated in the section on Piper hispidinervium in Chapter 3 are applicable to other tree crops and the sequence of events which are needed to develop them. In the case of Eucalyptus it is possible to grow it as a multipurpose crop from which fuelwood or poles can be produced as well as oil. Slower-growing trees such as rosewood and sandal are more difficult to bring under cultivation but the possibility of utilizing sustainably harvested rosewood leaf, rather than wood, as a source of essential oil might be possible; and the successful cultivation of sandal in India in areas of natural stands not susceptible to spike disease may yet be achieved.
Harvesting of wild forest trees or shrubs is conceptually attractive, particularly if it involves non-destructive harvesting of aerial parts such as leaves or terminal branches which quickly regrow. However, the problems of collecting material that may be scattered over wide areas, perhaps of difficult terrain, are great. The supply of raw material for distillation would be unpredictable and probably too small to meet market demand, and the variability and uncertainty of the oil quality from widely sourced biomass would create further problems.
Bringing trees under cultivation has advantages insofar as both inputs and outputs are well-defined and can be controlled and adjusted as the needs demand. Selection and improvement of planting stock as a means of improving oil quality and productivity - which are not options when utilising wild trees - also become possible. Provision of sustainably harvested plant material for distillation can be undertaken in several ways: on a smallholder basis, with farmers owning individual distillation units; by some form of cooperative in which individual outgrowers contribute raw material to a single distillery; or through an estate feeding a central distillery.
Whatever the fashions of the day, flavours and fragrances of plant origin will continue to be in demand. And whatever form of exploitation is best suited to forest and man - natural stands, monocultures or mixed cropping systems - the opportunities for developing countries will remain.
COPPEN, J.J.W. and GREEN, C.L. (1993) Options for development of new essential oil industries with special reference to Malaysia. 12 pp. Presented at International Conference on Essential Oils, Fragrances and Flavours, Kuala Lumpur, 31 October-4 November, 1993.
GREEN, C.L. and HONE, G.A. (1992) Essential oil production in developing countries. pp. 197-202. In Proceedings of the 3rd International Conference on Aromatic and Medicinal Plants, Nyons, France, 2-4 December, 1991.
LAWRENCE, B.M. (1985) A review of the world production of essential oils (1984). Perfumer and Flavorist, 10(5), 1-16.
LAWRENCE, B.M. (1993) A planning scheme to evaluate new aromatic plants for the flavour and fragrance industries. pp. 620-627. In New Crops. Janick, J. and Simon, J.E. (eds). 710 pp. New York: John Wiley & Sons.
VERLET, N. (1993) Commercial aspects [of essential oil production]. pp. 137-174. In Volatile Oil Crops: Their Biology, Biochemistry and Production. Hay, R.K.M. and Waterman, P.G. (eds). 185 pp. Harlow, UK: Longman.