Profile of Agarwood Tree

AGARWOOD 

Common Name:             Agarwood, Aloeswood, Oud, 
Scientific Name:            Aquilaria crassna
Categories       :            Threatened Species, Cosmetic/Medicinal;

Introduction
Aquilaria crassna is a tree species that has been of great ethnobotanical importance to people throughout the Greater Mekong region and beyond. Its heartwood and resin are highly valued commodities that have been transported along long-established trade routes for thousands of years. However, this species has now become Critically Endangered, owing to over-exploitation. Currently the majority of Agarwood comes from wild populations and there is now a very real danger this species may become extinct if wild harvesting continues at the current rate. To conserve this species, it is vital that this plant becomes more widely grown in cultivation, to reduce the pressure on the few wild populations that remain.

* Why is this species important?
The timber of this species is known as the ‘Wood of the Gods’ and has been known and highly appreciated for thousands of years. There is a strong connection that exists between the use of the wood, religion and curative properties.

* Where is it found?

This species has a fairly wide distribution and is found is Vietnam, Cambodia, Laos and Thailand. Aquilaria crassna is a light-demanding species, which grows scattered through natural forest on rocky, shallow, ferralitic soils, often growing alongside streams. It grows within an altitudinal range of 300-900m.

   * How do people use it?
The wood from Aquilaria crassna contains aromatic resin, known as ‘gaharu’. This is produced by the tree in response to injury if the production of callus tissue is inhibited. It acts as a chemical barrier to attack by insects and fungi. However, under natural conditions gaharu is not produced by trees at all. This resin is often used in temples as perfume wood. The wood can also be distilled to yield a valuable essential oil, which is widely used in Chinese and Southern Asian medicine and also in the Middle East for making perfumes and cosmetics.

  * Why is it threatened?

Economic exploitation of this tree for both its heartwood and oil has significantly reduced the natural range of the species and has placed it under threat. Unregulated collection of both seeds and saplings from the wild occurs widely, and good income can be earnt from selling these plants. This has also reduced reproductive capacity of the species, and it now only grows in scattered stands with low numbers of individuals.

* What conservation action is needed?

To conserve this species, the Vietnam Tree Seed Project has established a demonstration seed orchard in cooperation with the Central Forest Seed Company. The objective of this project is to promote the use of this species in non-timber plantations to enhance ex-situ conservation. This will help to reduce the pressure on harvesting from wild populations. It is essential that the seed orchards are used as a tool to raise awareness of the importance of conserving this species. They will also help to maintain genetic diversity among the species population. Further advantages of this project are that its methodology can eventually be implemented elsewhere and cultivation of the plant leads to valuable extra income for local people.

* Acknowledgements

Many thanks to BGCI for writing this profile.

* Selected references

Jensen, Anders and Meilby, Henrik (2008) ‘Does commercialisation of a non-timber forest produce reduce ecological impact? A case study of the Critically Endangered Aquilaria crassna in Lao PDR’, Oryx (Volume 42, Issue 2): pp. 214 -221;

                           

What is Agarwood ?

Agarwood is a resinous heartwood that sometimes occurs in trees belonging to the genus Aquilaria  (Thymelaeceae family). Aquilaria is a fast-growing, archaic subtropical forest tree, with a population range stretching from South Asia’s Himalayan foothills, throughout Southeast Asia, and into the rainforests of Papua New Guinea. It grows at elevations from a few meters above sea level to about 1000 meters, with approx. 500 meters being most ideal. Aquilaria can grow on a wide range of soils, including poor sandy soil. Seedlings require a great deal of shade and water but will grow rapidly, producing flowers and seeds as early as four years old. At least fifteen species of Aquilaria are known to produce the much sought-after agarwood. In South Asia, particularly India, Aquilaria achalloga is found. Aquilaria malaccensis is mostly known from Malaysia and Indonesia, whileAquilaria crassna grows primarily in Indochina. A number of others are also known, such asAquilaria grandfolia, Aquilaria chinesis etc., though these are relatively minor species for agarwood production.

Usage :-

The “Wood of the Gods” has been traded and highly coveted for thousands of years. The resinous wood is used as incense, for medicinal purposes, and pure resin in distilled form is used as an essential oil as well as a perfume component. Outside its native countries, it is most widely known in the Middle East, China, Taiwan, and Japan. A strong connection exists between use, religion, and curative properties, and elaborate traditional and religious ceremonies are known around the world. Faith healers in the Middle East use it at curative ceremonies, Japanese pilgrims donate flowers and agarwood oil to Shinto-Buddhist temples, and Vietnamese religious groups are obliged to bring agarwood to ceremonies at their temples in Mekong Delta communities.

Value :-

The value of first-grade Agarwood is extremely high. A wide array of products of different grades is available on the market, varying with geographical location and cultural deposition. Prices range from a few dollars per kilo for the lowest quality to over thirty thousand US dollars for top quality oil and resinous wood. Aquilaria crassna is listed as a critically endangered species in Viet Nam, and A. malaccensis is listed as vulnerable by the World Conservation Union, IUCN.

Extinction :-

Resin-producing trees are endangered throughout their known habitat all across Southeast Asia. The main driving force, which initiated this project, was the recognition of unsustainable Aquilariaharvesting in natural forests that resulted in the near extinction of this tree genus in Viet Nam and elsewhere. Aquilaria crassna is now a protected species in Viet Nam. Trade and harvesting restrictions will be virtually impossible to implement and enforce if no alternative is developed to forest-based harvesting. In addition, both in the short and long-term, a natural resource base needs to be maintained to supply present and future Aquilaria plantations with genetic source material in order to prevent plant decease, maintain diversity, and possibly improve resin production.

Substitutes :-

Development of synthetic substitutes usually arises when sustainable supplies of the natural product are not available. One of the first questions pursued when contemplating the pilot project was, “Is it possible to synthesize agarwood and agarwood oil?” The answer is a qualified no. Agarwood cannot be synthesized. Chemical substitutes are already available for perfume; these are cheap and constitute the least profitable end of the market. In addition, these products do not come close in emulating the natural product and thus do not pose a threat to producing non-synthetic agarwood products. The major chemical components responsible for the characteristic scent of agarwood products, 15-carbon chain compounds called sesquiterterpenes, can in principle be synthesized. However, these are very complicated structures that are extremely expensive to synthesize, which makes it commercially unattractive.

AGARWOOD OIL INDUSTRY

Agarwood is a resinous, fragrant and high valuable heartwood. The scientific name isAquilaria. It is also known as aloeswood,eaglewood, krissana in Thailand, gaharu in Malaysia and Indonesia, Oudh in the MiddleEast, chen-xiang in Chinese and jin-koh in Japan.Healthy agarwood is relatively light andpalecoloured.When the wood is infectedby a disease in the wild, the infection process producesa darkaromatic resin in
response to the attack. This results in a very
dense, dark, resin embedded hardwood.
This resin is highly prized and commands
an exceptionally high value because of its
distinctive fragrance and medicinal benefits.
The international trade in agarwood involves wood, wood chips, powder and oil.
Agarwood oil is also known as Oudh oil or Oud oil. The oil is conventionally obtained by the waterdistillation
process.
Agarwood oil can be applied directly to the
skin. Pure agarwood oil has a slow release
effect lasting at least 8 hours.

A small amount of agarwood oil can be
added to other oils to give a rich and
complex depth and to fix the aroma of
middle or top notes in perfume blending.
Pure agarwood oil is also burned as
incense, especially in Japan. It is used in
spiritual ceremonies or holy occasions as a
temple offering in the Muslim, Hindu and
Buddhist traditions.

* THE GLOBAL AGARWOOD MARKET :-

Globally, there are two major agarwood consumption regions:
• North-east Asia and the markets of Taiwan, Japan, and the Republic of Korea, and
• West Asia or the “Middle East” which centres on the countries of the Arabian Peninsula.
The uses of this resinous wood include
medicinal, religious and cultural applications in
various societies across Asia. No agarwoodproducing
species is known to grow west of
India, and yet it has been a traded item within
Arab-speaking commerce for over 2,000 years,
being sourced from both India and further east in
South-east Asia.


* AGARWOOD OIL: POSSIBLE USES AND HEALTH BENEFITS :-

When used in aromatherapy agarwood oil (Oud
oil) may help to treat anxiety, stress, depression
and other nervous system disorders.
Agarwood oil is used to treat cirrhosis of the
liver, kidney problems and lung and stomach
tumours.
Agarwood oil is also used as an anti-rheumatic,
an anti-convulsant, an anti-asthmatic, and a

carminative diuretic as well as an aphrodisiac.

* AQUILARIA SPECIES PRODUCES AGARWOOD :-

There are 17 species of Aquilaria, which can produce agarwood. Among them A. agollocha, A.
malaccensis and A. crassna are the best known. One of the main reasons for the relative rarity and
high cost of agarwood is the depletion of the wild resource. The endangered A. malaccensis has been
protected worldwide under the CITES convention since 1995 while all Aquilaria species have
received CITES protection since 2004. However, a number of countries have reservations outstanding
regarding this. In Bangkok, we are doing research work in conjunction with Asia Plantations to

develop the growing of Aquilaria trees in plantations to develop a sustainable source of Oud Oil.

* FACTS ABOUT AGARWOOD :-

• An 80-year-old Aquilaria tree can yield
6-9 kg of agarwood oil.
• A 50-year-old Aquilaria tree can yield
2.7 to 3.6 kg of agarwood oil.
• The amount of oud oil that is extracted
from each tree is not constant. Amounts
vary from using 1.2 kg to 3.6 kg of wood
to produce 1 tola (12 ml) of oud oil.
• The yield is totally dependent on the
infection level of the tree, also known as

resin formation.

* NATURAL RESIN FORMATION :-

The production of resinous compounds is a result
of a plant defence mechanism associated with
wounding; insects possibly assist fungal
invasion.
Phaeoacremonium parasitica is an important
fungus dealing with the resin formation process.
Naturally, the process of resin accumulation may
take many years and the longer the process, the
more expensive and highly valuable the resin.

* ARTIFICIAL RESIN FORMATION :-

First, a tree is drilled to make a hole about 5 mm
in diameter, with a 25 cm space in between the
holes.
Second, one ml of liquid inoculum is injected
with a syringe.
One month after inoculation, the effectiveness of
the process is checked by peeling the tree bark to
observe the disease symptoms.
A 7-8 year old plantation tree yields between 2-4

tolas of Oud oil.

* RESINOUS COMPOUNDS :-
The resinous compounds in agarwood oil
are detected by the Gas Chromatography-
Mass Spectrometry (GC-MS) method.
Many chemical compounds are found in
Oud oil. Some major chemical
constituents that make agarwood oils
distinctive from other oils include:
• Agarol
• Agarospiral
• α-agarofuran and β-agarofuran
• Eudesmol
• Jinkohol-eremol
• Guaiol
• Selinene

• 2-(2-phenylethyl) chromone.

* RESINOUS COMPOUNDS :-
Some of these chemical compounds were
scientifically reported to have medicinal

benefits.
• Agarol is an effective, gentle and
pleasant tasting laxative
• Agarospiral and Jinkohol-eremol
are considered to be neuroleptic
• Agarofuran is an anti-tumour
compound
• α-eudesmol can protect against
brain injury
• Guaiol can be used as skin
lightening product
• Selinene has anti inflammatory
effects
• 2-(2-phenylethyl) chromone shows cytotoxicity against the human gastric cancer cell line.

* EXTRACTION PROCESS :-

The extraction process also affects the oil yields.
Water distillation methods using traditional apparatus is time
consuming with high-energy consumption and low yields. The
picture on the left shows the conventional distillation plant

with wood fired stoves.
The right hand picture is a modified distillation plant with gas fired
stoves and agitation systems. Energy and mass transfers have been
improved on the later model. However, the distillation system still
requires on-going research and modification.
Solvent extraction can be used in combination with distillation.
A hydrocarbon solvent is put in with the wood dust and
dissolves the essential oil. The resulting solution is then filtered
and put through a distillation process that concentrates the oil to
produce a resin. The remaining substance is a combination of
wax and essential oil called "concrete".
The supercritical fluid extraction method is non-flammable,
non-toxic, and chemically stable and consumes less energy. It
provides some advantages over the classical method, since
supercritical carbon dioxide has low viscosity, high diffusivity,
and good transport properties and gives faster extraction and
high yields.The extraction process can be further enhanced by a pre-treatment process that is affected by many
parameters including wood chip size, solid to liquid ratio, pH, soaking time and agitation speed. For
the distillation process more study and research is still required. There are questions such as whether
water or steam distillation is better. The impacts of pressure, temperature and distillation time should
be further investigated.
For solvent extraction, the effects of the different types of solvents, pressure, temperature, extraction
time and agitation speed should be studied.

Fungus Treatment of Agar

Traditional knowledge suggests that fungi growing in a wounded aquilaria tree may cause Agarwood formation. Different types of fungi have been suggested including:

• Phialophora parasitica, 
• Torula sp.,
• Aspergillus sp.,
• Penicillium sp.,
• Fusarium sp.,
• Cladosporium sp.,
• Epicoccum granulatum, Cylimndrocladium,
• Sphaeropsis sp.,
• Botryodiplodia theobromae,
• Trichoderma sp.,
• Phomopsis sp., and
• Cunninghamella echinulata.
With all of these fungi suggested as a possible cause and no clear definitive research to show that a fungus is responsible for Agarwood to form, researchers have indicated "that aguru arises from a much more generalized cause than previously envisaged" (Gibson, Bano Biggyan Patrika 6:16-26 (1977)).
Agarwood is derived from the diseased timber of Aquilaria spp of the family Thymelaeaceae. Cutting or burning may be the way to infect fungi naturally in the wood tissue in vivo tree. The fungus Melanotus flavolivens has successfully been used to induce artificially the formation of Agarwood in Aquilaria sinensis in vivo. When the wood tissue of A. Sinensis was infected with the fungus M. flavolivens the color of infected wood tissue was first change from white to brown. (China – ASEAN workshop on Conservation and Biotechnology Application of Tropical Resource, Haikou, China, October 2004
- Aquilaria crassna, A. cumingiana, A. beccariana, A. hirta, A. malaccensis, A. microcarpa and A. rugosa
- Neighboring genera of the same family: Aetoxylon, Amyxa, Gonystylus, Gyrinops, Phaleria and perhaps genera Linostoma and Wikstroemia produce a resin after infection with fungi into the phloem and then spread to hardwood species with resin production into the phloem after fungus infection.

Lao PDR will be the sustainable market of Agarwood products by year 2015.
The price of Agarwood after fungal infection of Aquilaria plantation:

 

Agarwood (Oudh)

Agarwood is reputed to be the most expensive wood in the world. There are many names for the resinous, fragrant heartwood produced primarily by trees in the genus Aquilaria. Most commonly, the resin is known as agarwood, aloeswood, eaglewood, gaharu, agalocha or oudh (In Arabic).

                Agarwood has been used to make high quality incense since centuries. The Chinese describe its smell as "a sweet, deep but balanced fragrance" and use it in religious and festive celebrations, and so do Arabian, Indian and Japanese people. Agarwood is also part of many traditional pharmacopoeias, dating back to medieval times and Chinese doctors still prescribe it for colds and disgestion problem. Oil extracted from agarwood is used in Arabian countries as a perfume.

                 Agarwood is a resinous heartwood that occurs in trees belonging to the species of Aquilaria, Aetoxylon (A.symeatalum) and Gonystylus genus of Thymelaeceae family. However, species of the genus Aquilaria are mostly known for the production of agarwood - it's a fast growing, evergreen tree.

 

                Agarwood or oudh forms as a reaction to fungal or bacterial attack. Trees, ocassionally become infected with a parasite mould secrete a fragrant, protective oil into wounded areas (roots, branches or sections of the trunk), which gradually become harder and dark brown to black. The heartwood (central part of a tree, which is darker in color than the sapwood) is relatively light and pale color before infection. Normally harvesters would cut only the infected parts in the hope that the tree would produce more of this resinous wood.

                                                 

                                  Aquilaria species that produce agarwood are found throughout Asia, while occur naturally in South and Southeast Asia. The Indian sub-continent was the main source of agarwood for many centuries but as trees became scarce in the middle of the twentieth century, extraction intensified in Indochina. Later on it was extended to Indonesia and Malaysia. Today Agarwood plantations exist in a number of countries, including Bangladesh, Bhutan, India, Laos, Myanmar, Papua New Guinea, Thailand and Vietnam.

It can grow on a wide range of soils, including poor sandy soil. Seedlings of most species establish best in shady, moist conditions, but large adult trees sometimes become emergent in the forest and can withstand full sun. Some species can be found growing on steep, rocky, exposed slopes, and in regions that experience a hot, dry season. The trees grow to 6-20 m tall.

The leaves are alternate, 5-11 cm long and 2-4 cm broad, with a short acuminate apex and an entire margin. The flowers are yellowish-green, produced in an umbel, the fruit is a woody capsule 2.5-3 cm long. At least fifteen species of Aquilaria trees are known to produce Agarwood.Aquillaria Malacenensis is considered to be the queen of Indonesian oudh. This tree can grow about 40 M or 131.23 ft in height with its diameter 80 cm. It is the best producer of agarwood resin and oil in Indonesia.

Agarwood is exported in various forms (wood chips, powder, oil and as finished products such as perfumes, incense and medicines), and the main importers are countries in the Middle and Far East - in particular the United Arab Emirates and Saudi Arabia (where agarwood is known as oudh), as well as Hong Kong, Taiwan and Japan.

EXTRACTION METHOD

   There are three methods through which agarwood oil is distilled namely, hydro-distillation, steam distillation and super critical CO2 extraction. However, the most common methods of distillation are hydro-distillation and steam distillation. Another thing that has its mark on the distillation of the oil is the age of the tree. Older trees have a higher resin content and just like a wine, old resin gets better with age. Speaking of the grading of agarwood oil, the best quality oil comes out from first distillation and after this the wood undergoes for second distillation and hence, it is graded accordingly the number of times it is cooked.

Oil coming from steam distillation is said to lack the three-dimensional smoky quality which comes from hydro-distilled oil. In both methods, after the oil has been distilled, it is filtered, sunned, and aged for a while. The more the oil aged, the better it will smell.

When is it needed to develop synthetic substitutes?

Development of synthetic substitutes usually arises when sustainable supplies of the natural product are not available and are expensive at the same time. Since, Agarwood cannot be synthesized, chemical substitutes are already available for perfume these are cheap and constitute the least profitable end of the market. In addition, these products do not come even close in mimicking the natural product. The major chemical components responsible for the characteristic scent of Agarwood products, sesquiterpenes, can in principle be synthesized. However, these are very complicated structures that will be extremely expensive to synthesize, which makes it commercially completely unattractive.

So the major difference in fragrances of oudh oil and synthetic oudh can be distinguished easily. Oudh smells heavenly, woody and balsamic and surrounds a warm aura of bitter sweet and woody nuance. Whereas, synthetic oudh smells plain woody, leathry and lacks that warm balsmic aura.

Economic cultivation of agarwoods

the demand for agarwood far exceeds supply. A 2007 study revealed that supply rates are only 40% of the demand and a litre of agarwood oil can be sold for around $US10,000 – 14,000 on the market (Vietnam Chemical Technology Institute, 2007). Indeed agarwood is reputed to be the most expensive wood in the world and it is estimated that specialized buyers are prepared to pay as much as ten times more for this product.

Agarwood is exported in various forms (wood chips, powder, oil and as finished products such as perfumes, incense and medicines), and the main importers are countries in the Middle and Far East – in particular the United Arab Emirates and Saudi Arabia (where agarwood is known as oudh), as well as Hong Kong, Taiwan and Japan.

While agarwood trees are growing ,intercrops such as patchouli, sugandhmantri, turmeric, ginger etc can be grown .You can compare 9-10 years of cultivated agarwood cultivation to 25-30 years of teakwood or sandalwood cultivation with more income potential in case of the former.

A 10 year old tree may yield around 100 kgs of useful wood which can be graded as distillable, semi infected and resinous woods. The value of wood in the international market range from a few dollars a kilo for the lowest quality to over thousands of dollars for the top quality. 

Planting Methods

Agarwood suitable for planting in the lowland areas to the mountains at an altitude of 0 – 750 meters above sea level with an average rainfall of less than 2000cm.  Appropriate temperature is between 27 ° C to 32 ° C with a rate of 70% sunlight. Suitability of land types soft and sandy clay soil with a pH between 4.0 to 6.0.

Quality seeds are essential for the purpose of seeding; seeding is usually done by the nursery to ensure the supply of crop seeds in a large volume and long lasting. Agarwood the fruits of Aquilaria Malaccencis the form of capsules, 3. 5 cm to 5 cm long, ovoid and dark brown. The skin is quite hard and contains one to two seeds per fruit.

Agarwood tree species are evergreen plants and growing. It is suitable for planting in most soils except swampy soil and stagnant water. Agarwood trees can be planted on flat land and hilly areas. It can also be planted in oil palm plantations, coffee plantations and farms in the other trees, aged between 5-8 years. Cultivation techniques in the interval system or integrated with two or more crops can be done .Technique Agro forestry approach, Inter-row planting and hedge planting also can be done.

Planting technique is to dig a hole in the distance measure 6 feet x 6 feet, 10 feet x 10 feet, 10 feet x 15 feet and so on. It depends on the techniques of crop interval, integration, or the like. Seedlings removed from the polythene bag and placed in a hole dug with an area of 0.5 meters in diameter and depth. Surface soil compacted by hand to ensure close contact with the ground roots and avoid the flow of water at the surface (surface water). Fertilizer application rates should not exceed 100 gm for every hole, namely the rate of fertilizer NPK 15:15:15 by 40-50 gm and TSP by 40-50 gm during the planting process.

Aquilaria trees planted must be cleaned from the interference of other trees about 50 cm to avoid the competition of life. Work-job is done in 2-3 times a year to five years old trees. Plugging two times a year is very good for giving oxygen into the ground to facilitate the absorption of food by plants.

P

lanting Village Residence

If that is the ability to grow only on a small scale, agarwood trees planted in the villages that do not involve the purchase of land and does not require a fence, that is, the area is already fenced. The cost just to buy the seeds and care for trees to work. Planted at least 100 trees.

If you can sell wholesale without inoculated at a price of RM 1,000 at the end of the 5-6 years can be obtained gross proceeds of RM 100,000. Or grown only to who will be able to next generation. When aged 5-6 years, nailed the trees injured by stick to stimulate the creation of resin. The farmers cannot afford to inoculate trees themselves because their cost is too expensive. They do not often depend on wood trees would become resin but may cut it down and sold some of Agarwood oil distiller which operates in the village as well.

Here also comes the aid of AGARWOODS KERALA in the form of very affordable inoculation methods in a very subsided rate and proven advises from the experts.

our plantation

Plantation and coffee estate owners in kottayam(kerala) finally have a reason to cheer despite the decreasing prices of their produce.

For the last five to six years, a wonder plant agarwood has replaced the conventional silver oak in many coffee estates bringing handsome dividends to growers. 

Agarwood is a high value commercial crop which is in great demand in national and international markets.

The tree is used to make ittar (natural perfume oil) and perfume.

The outer part of the stem, which is of low quality is used to make incense sticks and in paper manufacturing industries.

An agarwood sapling is easy to grow as its maintenance is inexpensive and it gives yield in eight years.

Traditionally, almost all coffee growers in India plant silver oaks as an intercrop providing shade to other plants.  Recently, coffee plantations in Western Ghats and Malnad region have started planting agarwood. The origin of the tree can be traced to the evergreen forests of Southeast Asia. 

Agarwood was first introduced in South India by Vanadurgi Agarwood India Limited (VAIL) which was formed with its shares distributed among planters, promoters and Vanadurgi Flavours and Extracts (P) Limited.

The company is exclusively involved in the planting, processing and marketing of agarwood.

VAIL Managing Director K N Dharmendra Kumar told Express that the company has distributed more than one million agarwood saplings to 5,000 plus growers across eight districts in  Malnad region.

The company has entered into a buy-back agreement with farmers to provide good seedlings, technical guidance, artificial inoculation, setting up of processing units and purchase of their inventories.

He said that 150 to 200 agarwood trees can be planted in one acre plot of coffee, arecanut or coconut plantation. 

Anil Ponnappa, a progressive coffee planter in Madapura said he has planted 600 agarwood trees supplied by VAIL in his coffee estate. Another agarwood grower N Vishwanath in Sagar, Shimoga district said he has planted 15,000 saplings on his dry land a year ago. “Agarwood is a good alternative to other crops whose prices are falling these days,” he added.

Agarwood is costlier than sandalwood in the international market as it is in great demand in Gulf countries.

A sandalwood tree takes at least 25-30 years to fully grow while an agarwood  takes tree takes only 8-15 years.

The inner stem (resinous) of agarwood is valued at `10,000 per kg while agarwood oil costs Rs 10 lakh per kg in the international market.  Agarwood is priced according to the density of wood, resin, purity, aroma and colour.