COFFEE
Source: Coffea arabicaL.,C.canephora
Pierre ex Froehner (syn.C.robustaLinden
ex De Wild.), and otherCoffeaspecies,
varieties or hybrids (Family Rubiaceae).
Common/vernacular names:Arabica, Arabi-
an, Colombian, or Santos coffee (C.arabica);
and robusta coffee (C.robusta).
GENERAL DESCRIPTION
Evergreen shrubs to small trees with two-
seeded, deeply crimson fruits (berries) that
are commonly called ‘‘cherries’’;C.arabica
up to 6 m andC.canephorato 8 m high;
believed to be native to Ethiopia; now exten-
sively cultivated in tropical and subtropical
countries. Parts used are the roasted seeds,
commonly called ‘‘beans’’.
During the production of coffee beans the
freshly picked ripe cherries are either sun
dried (requiring 2–3 weeks), followed by me-
chanical removal of the dried husk (pulp, skin,
etc.) and seed coat, or they are placed in water
and subjected to pulping machines to remove
most of the pulp, followed by fermentation
(requiring up to several days), drying, and
mechanical removal of the silver skin. The
former method is called the dry process, and
the latter is called the wet process, producing
respectively the so-called natural and washed
coffees. The dried beans at this stage are
known as green coffee and are exported.1,2
Arabica coffee is produced mostly in South
and Central America, particularly Brazil, Co-
lombia,Mexico,andGuatemala,while robusta
coffee isproducedmainly byAfrican countries
(Ivory Coast, Uganda, Angola, etc.).1,2
In the United States, Colombian and
Central American coffees are preferred over
Brazilian and African coffees.
To develop the characteristic coffee aroma
and taste, the green coffee is roasted to the
required time at temperatures up to about
220 C, depending on the types of coffee beans
to be produced. During roasting, the beans
acquire their typical flavor, at the same time
turning dark and slightly increasing in size
(swelling) as well as losing weight (due to loss
of moisture, carbon dioxide, and other volatile
compounds from pyrolysis). Coffee beans are
often blended before or after roasting to pro-
duce various commercial grades or brands.1,2
Decaffeinated coffee is produced by re-
moving most of its caffeine content while at
the green coffee stage, generally by extraction
of the whole beans with organic (e.g., chlori-
nated) solvents. The beans are then rid of
solvent and roasted.1,2
Instant coffee is produced by extracting
ground-roasted coffee with hot water, often
under pressure. The extract is concentrated
and freeze-dried or spray-dried to produce a
granular or powdered product. For instant
coffee manufacture, robusta coffees are more
commonly used due probably to their higher
contents of soluble materials and thus giving
higher yields.1,2
Coffee extracts for flavoring purposes are
prepared by extracting roasted coffee with
water or water–alcohol mixtures.1,2CHEMICAL COMPOSITIONGreen coffee contains 0.6–3.2% (usually
1.5–2.5%) caffeine; 0.3–1.3% trigonelline;
5–10% chlorogenic acid (robusta more than
arabica);^3 7.4–17% oil called coffee oil (arab-
ica more than robusta);1,2,4up to 60% carbo-
hydrates (mostlyagalactomannan);5–7protein
(ca. 12%); about 2% free amino acids con-
sisting mainly of glutamic and aspartic acids
and asparagine;^8 polyamines (putrescine,
spermine, and spermidine);^9 tannins (ca.
9%); B vitaminsand trace of niacin; and others
(LIST AND HO ̈RHAMMER;MERCK;MORTON3;WATT
AND MERRILL).1,2,10
Coffee oil contains mainly glycerides of
fatty acids (e.g., linoleic, palmitic, oleic, and
stearic acids, with the first two in predominant
concentrations) and 5–8% of unsaponifiable
matter, which consists of squalene,n-nonaco-
sane, lanosterol, cafestol, cahweol, sitosterol,
stigmasterol, methylsterols, tocopherols (a,b,222 Coffee