It’s difficult enough to classify coffee trees because of their extreme variety. All in all there exist about eighty kinds of coffee trees - from dwarfish bushes to 10-metre giants among which only 4 principal sorts are distinguished. Among them only two botanical kinds of coffee trees are of great interest for connoisseurs of coffee. They are Coffee"Arabica", still known as the Arabian coffee, and Coffea Coffea Canephora (Robusta coffee) which sometimes is called Congolese coffee.
Other two versions of a coffee tree is Coffea Liberica discovered in Liberia in 1843, and Coffea Dewevrei with its most known subspecies is Excelsa. They possess qualities of Robusta coffee and quite comprehensible though not very pleasant taste.
It is necessary to understand a difference between concepts «a coffee kind» and «a coffee grade». To name Arabica, Robusta coffee, Liberica or Excelsa a grade is incorrect - they are kinds, versions of a coffee tree, to be more exact. Each kind has many grades.
Selectors for decades tried to breed new kinds of coffee which would have high productivity, high resistibility to illnesses, and would give high-quality coffee. However their attempts were vain - the majority of hybrids though gave the big crop and had high resistibility, but coffee was of much worse quality than the versions of coffee trees used for selection.
The official name of a plant is the Arabian Coffee Tree (Coffee Arabica). Arabica is the most important kind of coffee in the world, notable for complicated aroma and taste.
Tree of Arabica is in height round 6-8 metres (however, it is not allowed to grow more than 4 metres for convenience of harvesting). The tree blooms with white fragrant flowers. A cherry of Arabica is in length round 14 millimetres, red colour, and towards the end of maturing becomes violet. Beans are extended, plano-convex, turned to each other with flat parts with longitudinal furrow.
The plant is extremely whimsical. It grows usually on mountain plateaus or on slopes of volcanoes at height 800-2100 meters above sea level where mid-annual level of precipitation reaches 1500-2000 mm and where warm days are changed by quite cold nights, at fluctuations of daily average temperatures from 15 to 24 degrees Celsius. For coffee cultivation total absence of frosts is necessary. Coffee trees of Arabica blossom after each season of rains, then cherries require about nine months for ripening.
Soil for cultivation of Arabica should be well fertilised and rich with set of minerals. The plant also is very sensitive to diseases. To prevent them, it is necessary to use pesticides and fungicides. Arabica propagates by beans.
The Arabica tree gives usually no more than 5 kg of beans per year that turns out to be about 1 kg of ready beans. In the majority of the countries the crop of Arabica is "washed", that is processed with water. Arabica beans are longer and straighter than Robusta beans, and are also less rich in caffeine, have gentle sourish aroma.
Arabica beans contain: 18 % of aromatic oils, 1-1,5 % of caffeine. The taste of the coffee made of Arabica is sweet, with a light sour taste. The best beans give the flavours of Arabica Typika, Bourbon and Maragogype.
Arabica makes almost 70 % of all coffee produced in the world. Today about 45-50 grades of Arabica are used in the coffee industry.
The official name of a plant is the Coffee Tree Canephora. It originates from the basin of Congo (Congo, Africa). Robusta coffee is a second in popularity in the world coffee kind, it is characterised by the high maintenance of caffeine in beans. Robusta coffee is used in coffee mixes for giving drink strengths.
Coffee from Canephore beans possesses lesser aroma and bigger strengths than Arabica, in addition this plant perfectly resists to illnesses and insects. However, coffee strength is not its most important characteristic and concerning taste Robusta coffee is far below Arabica. That’s why Robusta coffee makes only 30 percent of coffee production in the world.
In spite of the fact that Robusta coffee trees are necessary to be artificially pollinated and looked after from first days of their life , this culture cultivating is nevertheless easier. An interesting fact in the history: when in the second half of the XIX century numerous plantations of Arabica were destroyed by rust instead Robusta coffee basically has been planted. Now it is grown up in tropics everywhere but the biggest suppliers of Robusta coffee are East and the Central Africa, South East Asia and Brazil.
Robusta coffee grows at height of 200-900 m above sea level, and is more stable concerning changes of a temperature mode and an amount of precipitation than Arabica. The coffee tree of Robusta is insensitive to diseases and harmful insects. Plantations do not demand careful care and are notable for high productivity.
Robusta coffee survives at very high temperature of air though 24-30 degrees of Celsius are optimum for it. Besides, Robusta coffee stands also very damp climate with precipitation level of 3000 mm and more but under trees the water should be stagnant in no case as rotting process begins and the plant dies off. Robusta propagates by cuttings.
Robusta coffee trees blossom separately and irregularly enough; their cherries need 10-11 months to ripen.
Beans are gathered usually manually and only in Brazil flat district and open space of plantations allow to reap crop with the help of machinery. Frequently the Robusta coffee crop is process in a "dry" way.
Robusta beans are small and roundish. They are easy for distinguishing on two small specks on both sides of the groove. From the hectare there received a little more Robusta coffees than Arabica. The Most known versions of Robusta coffee is Konilion du Brazil, Java Ineak, Nanu, Kuilu and Kongensys.
Robusta coffee beans contain 8 % of aromatic oils, 3 % of caffeine. Robusta coffee is used mainly in mixes where it is very valuable component due to its high strengths. At processing too spicy taste of Robusta is a little softened. In Italy it is added in espresso mixes for getting steadier and dense scum.
The official name of a plant is the Liberian Coffee Tree (Coffea Liberica). Liberian coffee comes from the Western Africa. Now this kind is cultivated almost in all countries of the African continent and also in Sri Lanka, Indonesia, Philippines and others.
Liberica coffee is got from cherries of coffee trees in height of 6-10 metres with very large leaves. The length of a coffee cherry is 30-35 mm, width - 10-15 mm.
Liberica is insensitive to almost all diseases of coffee trees.
Quality of Liberica beans is not the highest therefore such grade of coffee is used seldom. On Liberica basic various mixes are created.
The official name of a plant is Coffea Dewevrei. That is one more kind of coffee. The Excelsa coffee or High Coffee is even less known than Liberica. Trees of this kind reach in height 20 m. This kind of coffee has no economic value.
The coffee fruit develops within 8-11 months after flower occurrence. The colour of a fruit during this period changes from light green to red and in period of definitive maturing it becomes dark-crimson. By appearance fruits at this moment remind a cherry, they grow in clusters. In each berry there are usually two "kernels", outwardly covered with pulp.
Coffee beans are stones of coffee berries, seeds of coffee trees. Coffee grain is surrounded by four covers: a dense brilliant external thin skin, pulp, a rigid cover-capsule in which both grains, and also the thin silvery pellicle covering each grain.
Coffee beans gathered within year from one tree are enough for getting 0, 5 - 1, 3 kg of roasted coffee.
Colour of beans can differ from pale-emerald and blue-green to brown-pale in the grains which have gone through long storage or decaffeinating.
The average size of non-roasted beans is about 0, 7 sm, but this characteristic depends on a place and growth conditions. Some kinds of beans surpass the usual ones in size, for example, Maragogype (“elephant” beans) - 2 times, Kenya АА and Colombia Supremo - 1, 5 times. The size of coffee beans plays an important role in its grade defining. Coffee beans are sorted by size corresponding beans' size:
|The size||Beans size, mm||The description|
|20||More than 8||Very big grain|
|19||7,543||Extra big grain|
|17||6,749||Big enough grain|
1 — a longitudinal fillet;
2 — a seed (endosperm);
3 — a seed peel (a silvery pellicle);
4 — endocarp (a pergament cover);
5 — a pectic layer;
6 — mesocarp (fruit pulp);
7 — exocarp (an external fruit cover)
Coffee beans when fresh contain alkaloid caffeine (0, 65-2,7 %), fats - about 12 %, the pro-teins - 13 %, sugar - 8 %. After thermal processing the maintenance of sugars decreases to 2-3 %, coffee tannic acids - to 4-5 %; the maintenance of fats raises to 15 %, nitrogenous substances - to 14, caffeine - to 1,3 %. In roasted beans there are phenolic connections, organic acids, vita-mins РР, pyridin, etc.
The sweet edible pulp of coffee cherries in Africa is used for preparation of alcoholic drinks and for caffeine reception.
Raw coffee beans are used for caffeine reception. Processing of beans for coffee drink manufacturing consists in their roasting at temperature of 150-200°С before brown colour acquisition.
Food value of coffee consists, first of all, in flavouring characteristics and property to remove temporarily drowsiness and weariness, to raise working capacity and creative activity due to caffeine. Drinking coffee is contraindicative for children, elder people, people with the hyperexcitability, ones suffering sleeplessness, hypertension, atherosclerosis, organic diseases of cardiovascular system, ill with gastric ulcer.
Coffee beans are used also as medicinal raw materials.
Beans contain purine alkaloid, caffeine is the main one. Caffeine is used as an excitant at nervous exhaustion and headache.
In medicine caffeine is more often applied in the form of its complex salt with sodium benzoate as an excitant at oppression of the central nervous system, for improvement of mental and physical working capacity, by narcotics poisoning, insufficiency of cardiovascular system, spasms of vascular system, cerebral vasospasm.
For people owing to certain circumstances, caffeine is counter-indicative, it is reccommended to drink coffee, undergone the process of decaffeinating. It is process of coffee beans’ losing some caffeine, but keeping all taste and aromatic properties. Thus we receive the coffee notable for more delicate taste and aroma. It is a first-rate quality product, safe for health. The last argument quite justifies high price of decaffeinated coffee.
The comparative characteristic of Arabica and Robusta coffee kinds
|The supposed native land of a kind||Ethiopia||Central Africa|
|Place and time of the first cultivation||The south of southern Arabia, apprx. XIV cent.||Congo, 1870|
|Tree height||3 - 5 m||Up to 13 m|
|Cultivation height above sea level||600 - 2500 m||200 - 900 m|
|Desirable temperature||+15... +24 °С||+24... +30 °С|
|Stability to illnesses and wreckers||Lower||Higher|
|The most known grades of a kind||Bourbon, Typica, Mocha||Kouilou, Nana|
|TASTE, AROMATIC AND CHEMICAL CHARACTERISTICS OF BEANS|
|General characteristics||more refined
less astringent taste
with noble sourness
|Caffeine maintenance||1,0 - 1,5 %||1,6 - 3,2 %|
|Oils and fat connections||Apprx. 18 %||Apprx. 8 - 9 %|
|Sugar||Apprx. 8 %||Apprx. 5 %|
|Share in world production||Apprx. 70 %||Apprx. 30 %|
|Use (mainly)||in coffee mixes
|for instant coffee manufacture
as an additive in coffee mixes