Coffee family, Rubiaceae

Rubiaceae

(Coffee family)

History and origin

It was accidentally noticed according to an Ethiopian legend (800 A.D.), that a particular flock of sheep while grazing, a few of the sheep instead of being drowsy in the night became very alert and sleepless, whenever the fruits of the coffee plant were eaten. The natives noticed the effect of the coffee plant on the animals and they started using the berries and leaves for intoxication and exhilaration. The people of Uganda were found chewing coffee beans when the first explorers from Europe reached the country. 

      The use of coffee was later practised by Arabians in Mecca around 1470 A.D. Coffee was introduced into Europe around 1620-1650. Later on it was introduced into Sri Lanka, Java, Sumatra, islands of Malaya Archipelago round about 1658. In India coffee was introduced by the British around 1690 and was later spread to tropical America and West Indies. 

                       Historically Sri Lanka, a leading producer of coffee, experienced a devastating disease of coffee called the 'leaf spot' or 'coffee rust' caused by the fungus called Hemileia vastatrix during the 19th century.

Species of Coffee

1. Coffea arabica L.

The species grows wild in forests on the high mountains in the south of Ethiopia. It has two botanical varieties known as var. arabica and var. bourbon, from which many cultivars have been derived. Var. arabica was, quite by chance, planted in Java, taken by the French to Martinique from where it was passed to South and Central America. In Brazil it is now called 'Nacionale' coffee. It was also planted in Nyasaland and Uganda. The var. bourbon was first grown by the French in Reunion islands. It has a better flavour than var. arabica.

                            C. arabica grows to height of 5-10 m in natural conditions, but under cultural conditions it is pruned to a height of 1.2-1.5 m. It has a main stem with lateral branches which grow in pairs opposite to each other and the leaves are opposite, thin , coriaceous and bright green in colour. The flowers are white, fragrant and are borne in clusters in the axils of the leaves. Flowers are pentamerous, with 5 epipetalous stamens and the ovary inferior. The fruits are small, fleshy drupes, bright green when young, changing to yellow and later scarlet red with ripening. The fruit consists of two oval grey seeds or beans contained in a mucilaginous pulp. The seeds are covered by a thin membrane, the silver skin. The seed with the membrane is in a common husk-like membrane, the parchment. The number of cotyledons are normally two.

       There are three important Indian varieties of arabica species and they are: 

• Chicks, a variety developed from Chikmagalur in Karnataka state and is favoured for its liquoring quality,
• Coorgs, also developed from Chikmagalur in Karnataka as a selection from Chicks, and
• Kents, ia a selection from the Coorgs and is very popular in India grown in Karnataka, Coorg and Nilgiri hills. It is resistant to leaf blight and a vigorous grower with high yield.

    2. C. canephora or C. robusto Linden (Congo coffee)

Robusta coffee grows wild in the forests of West Africa and Congo. It is even found in the forests of Uganda. It grows strongly in areas warmer than those in which Arabian coffee is grown, and it is not so susceptible to diseases. Though flavoured, it is cheaper and not as good as Arabian coffee. There are two varieties: true robusta variety. with stiff upright growth, and the other is Uganda or Quillon variety, with many stems and forms itself into a bush.  

    3. C. liberica Bull ex Hiren (Liberian coffee)

A large tree 13-16 m high, with fruits about 2.5 cm diameter. The plant thrives well in low altitudes, hot climates and even poor soils. Its berries have a strong flavour, and are inferior in quality when compared to Coffea arabica. It is native of west tropical Africa and is cultivated in Malaya. In India it is cultivated in Mysore and in Travancore. C. liberica has been widely used for hybridisation purposes and as a root stock for grafting C. arabica. Some of the hybrids show resistance of leaf diseases and are vigorous. 

  4. C. excelsa A. Chev (Excelsa coffee)

It is native of west Africa and is grown in Philippines, Java and Vietnam. It is a large tree and takes twelve months for bearing the berries.

Coffee growing countries in the World

The important coffee growing countries in the world are: Angola, Brazil, Columbia, Costa Rica, Dominican Republic, El Salvador, Guatemala, Haiti, India, Sri Lanka, Indonesia, Kenya, Tanganyika, Mexico, Venezuela, Nyasaland, Congo.

Important coffee producing states in India are:

Tamil Nadu- Nilgiris, Malabar, Madura, Salem and Coimbatore.

Orissa-  on small scale

Karnataka- Chikmagalur, Hassan, Mysore and Shimoga districts.

Kerala- Travancore and Cochin districts.

Ecology

Coffee grows well with medium annual rainfall provided it is well spread over nine months of the year. There must always be plenty of moisture in the subsoil. A constant temperature between 15-21 degree C is best for Arabian coffee. Coffee plant cannot stand cold winds, or dry hot winds. Coffee trees like a deep rich soil with neutral pH. The crop prefers humid cool weather. It is necessary keep the soil shaded by placing a grass mulch or by growing beans of Laucaena glauca. 

Cultivation practices

Coffee can be propagated by sowing seeds. The selected seed is sown in nursery beds. Coffee seed takes from 35-40 days to germinate. Seedlings should be ready to plant when it is 180 days old and planting should take place in dull and rainy weather, preferably at the beginning of a wet season.

Harvesting

There are several methods of harvesting coffee used in different countries of the world by which 'mild', 'soft' and 'hard' coffees are obtained. Usually coffee fruits are picked when they are red-ripe. The outcome of clean, dry coffee from ripe fruit is about 16-18%.

Structure of the coffee fruit

A transverse section of the fruit of coffee shows an outer thin exocarp, an inner thin endocarp (parchment) and a middle stony mesocarp enclosing two seeds covered by the testa (silver skin). The bulk of the seed contains the endosperm containing the different chemical constituents of coffee.

                                                                 The dried coffee beans are oval in shape, about 1.2-2.5 cm in length, convex on one side and flat on the other side. The colour of the seeds varies from dark blue to yellow depending upon the soil, variety, climate and other regional factors and on the preparatory process. Raw coffee has a peculiar odour and is harsh to taste with a slightly sweetish taste. 

Chemical composition

The average composition of coffee beans is as follows:

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                                 Raw beans  (sp.gr.)         Roasted coffee (sp.gr.)

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    Moisture-                  8.98                                    0.63
    Protein-                     9.87                                   11.23
    Caffeine-                   1.08                                    0.82
    Fat-                            12.60                                13.59
    Sugar-                         9.55                                   0.43
    Dextrins-                    0.87                                    1.24
    Caffetannic acid-        8.46                                    4.74
   Ash-                             3.74 percent                       4.56 percent

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Source: Wealth of India

Alkaloids

The caffeine content of the beans vary in different species of C. arabica, 1.0-1.2 percent, C. liberica, 1.4-1.6 percent, C, robusta, 1.5-2.5 percent and C. mauritiana, 0.07 percent. Caffeine is an important constituent of coffee and is responsible for the stimulating effect of the coffee drink. The flavour of roasted coffee depends to a large extent on the manner and extent of roasting. Prolonged roasting renders coffee bitter and acrid, while under- roasting affects the extraction of caffeine in the liquor. The market value of coffee depends on the so called cup quality, colour, brightness and evenness of the roasted beans. It is also determined by the specific gravity of the bean and also the locality in which the coffee is produced.

Adulterants and substitutes

Many coffee drinkers prefer coffee mixed with chicory which is obtained from the chicory root (Cichorium intybus Linn. Asteraceae). The chicory powder is mixed with pure coffee in different ratios for flavouring and grading. A product called Malz coffee is prepared by adding malted barley and wheat to pure coffee.

          The common adulterants of coffee seeds are seeds of Cassia tora Linn., Tamarindus indica Linn. peas, beans and caramel. The common substitutes of coffee are leguminous seeds like Cassia tora, C. occidentalis Linn., Glycine max Merr and Canavalia ensiformis.

Instant coffee

Nowadays coffee manufacturers are inclined to produce instant coffee which is directly used for preparing coffee by mixing the powder directly in the milk. Instant coffee is obtained by vaporising a strong infusion of coffee in vacuum or by freeze drying technique.

Processing coffee seeds

The cherry coffee is put in tank filled with running water and immature fruits that float are removed. Then the fruits are subjected to pulping in coffee pulpers which separate the coffee seed from the pulp. The seeds emerging from the pulper are known as parchment coffee Parchment coffee is roasted sufficiently to remove the sticky mucilage and to impart flavour. After fermenting, the seeds are washed. The coffee seed is dried in the sun or mechanical dryer.

Uses

1. Coffee is mainly used as a beverage in the form of aqueous extract prepared from roasted and powdered beans. The extract has a bitter taste and characteristic aroma and a stimulating effect.
2. It is used in medicine as a diuretic, and a beverage to convalescent people. The disturbances in digestion by use of coffee are due to volatile toxic substance present, called cafeotoxin.
3. The leaves of coffee are also used as a beverage in certain parts of Malaya.
4. Coffee pulp, a by-product in the manufacture of parchment or plantation coffee is used as cattle feed.
5. Coffee beans are used in the manufacture of plastic called Caffelite.
6. The wood of coffee tree is hard and can be used as a box wood and the branches of the coffee plant are used as walking sticks and hammer handles.

Diseases

Fungal diseases

• Leaf rust caused by Hemileia vastatrix.
• American leaf spot caused by Mycena flavida.
• Coffee berry disease caused by Colletotrichum coffeanum.
• Tracheomycosis Wilt (root wilting) caused by Fusarium xylarioides.
• root rots caused by Rosellinia bands and Armillaria mellae.

Rubiaceae

(Coffee or madder family)

Ixora

Gardenia

Mostly trees (Cinchona officinalis) or shrubs (Mussaenda luteola, Hamelia patens); however those in north temperate regions are mostly herbs (e.g. species of Gallium, Oldenlandia); sometimes hook climber (Uncaria) or vines. Rubiaceae is a family of about 500 genera and 6500 species, chiefly distributed in tropics, but some are distributed in in temperate and even arctic regions (Galium). About 75 genera and 275 species have been reported from India, chiefly in tropical and subtropical eastern Himalayas. 

Some of the largely represented genera are: 

• Psychotria, Galium, 
• Ixora, Gardenia, 
• Mussaenda, 
• Asperula, 
• Cephalis, 
• Rondeletia, 
• Coprosoma, 
• Guettarda, 
• Rubia, 
• Coffea and 
• Cinchona. 

Selected Indian genera are- 

• Cinchona, 
• Coffea, 
• Gardenia, 
• Ixora, 
• Mussaenda, 
• Rubia and 
• Oldenlandia. 
• Two most important plants of the family are Coffea arabica (coffee yielding plant) and species of Cinchona (quinine yielding plant).

Economic importance 

Ornamental plants: 

Some of the common ornamental plants grown in gardens and roadsides include 

• Anthocephalis cadamba (kadam) 
• Cephalanthus occidentalis
• Galium verum (ladies bedstraw) 
• Gardenia jasminoides (Jasmine)
• G. lucida 
• Hamelia patens 
• Hamiltonia suaveolens (Padera)
• Ixora arborea
• I. coccinia
• Morinda tinctoria
• Mussaenda frondosa
• M. luteola
• Pentas lanceolata and
• Rondeletia

Coffee:

Coffee, the most popular nonalcoholic, caffeine containing beverage of the world comes mainly from the roasted and powdered seeds of Coffee arabica. Other coffee producing species are C. liberica and C. robusta.

Quinine:

This famous drug, used throughout the world in the treatment of of malaria, comes from the bark of several species of Cinchona such as C. calisaya, C. ledgeriana and C. officinalis.

Other Medicinal plants:

• Cephaelis ipecacuanha (Ipecac) roots are used against amoebic dysentery and pyorrhoea,
• Gardenia gummifera produces gum as a carminative stimulant,
• Randia tinctoria fruit pulp is emetic and anthelmintic,
• Paederia foetida is used in indigestion and stomach troubles.

Dyes:

• Roots of Rubia tinctoria (madder) contain dye alizarin and purpurin, 
• while that of several other species of Morinda contain red  (M. tinctoria, M. bracteata) and 
• yellow (M. citridora) dye. 
• Red dye is also obtained from the root bark of Oldenlandia umbellata.

Timber:

Useful timber is obtained from several species of this family, such as: 

• Adina cordifolia (haldu), 
• Anthocephalus cadamba, 
• Ixora ferrea, 
• Mitragyna parviflora and 
• Randia spinosa.