2009_Book_FoodChemistry

21 Coffee, Tea, Cocoa
21.1 Coffee and Coffee Substitutes
21.1.1 Foreword
Coffee (coffee beans) includes the seeds of crimson
fruits from which the outer pericarp is completely
removed and the silverskin (spermoderm)
is occasionally removed. The seeds may be raw or
roasted, whole or ground, and should be from the
botanical genus Coffea. The drink prepared from
such seeds is also called coffee.
Coffee is native to Africa (Ethiopia). From there it
reached Arabia, then Constantinople and Venice.
Regardless of the prohibition of use and medical
warnings, coffee had spread all over Europe by
the middle of the 17th century. The coffee tree
or shrub belongs to the family Rubiaceae. Depending
on the species, it can grow from 3–12 m
in height. The shrubs are pruned to keep them at
2–2.5 m height and thus facilitate harvesting. The
evergreen shrubs have leathery short-stemmed
leaves and white, jasmin-like fragrant flowers
from which the stone fruit, cherry-like berries,
develop with a diameter of about 1.5cm. The
fruit or berry (Fig. 21.1) has a green outer
skin which, when ripe, turns red-violet or
deep red and encloses the sweet mesocarp or
the pulp and the stone-fruit bean. The latter
consists of two elliptical hemispheres with
flattened adjacent sides. A yellowish transparent
spermoderm, or silverskin, covers each hemisphere.
Covering both hemispheres and separating
them from each other is the strong fibrous
endocarp, called the “parchment”. Occasionally,
10–15% of the fruit berries consist of only one
spherical bean (“peaberry” or “caracol”), which
often brings a premium price.
The coffee shrub thrives in high tropical altitudes
(600–1200 m) with an annual average
temperature of 15–25 ◦ C and moderate moisture
and cloudiness. The shrubs start to bloom 3–4
years after planting and after six years of growth
they provide a full harvest. The shrubs can bear
fruit for 40 years, but the maximum yield is
attained after 10–15 years. Fruit ripening occurs
within 8–12 months after flowering. Only 3 of
the 70 species of coffee are cultivated: Coffea
arabica, which provides 75% of the world’s production;
C. canephora, about 25%; and C. liberica
and others, less than 1%. The quantity (in
Table 21.1. Production of coffee beans in 2006 (1000 t)
Continent Raw Country Raw
coffee
coffee
World 7843 Brazil 2593
Viet Nam 854
Africa 922 Colombia 696
America, Central 1020 Indonesia 653
America, North 3 Mexico 288
America, South India 274
and Caribbean 4782 Ethiopia 260
Asia 2069 Guatemala 257
Europe – Honduras 191
Oceania 68 Peru 175
Fig. 21.1. Longitudinal section of a coffee fruit (according
to Vitzthum, 1976)
a World production = 100%.
∑ (%) a 75
H.-D. Belitz · W. Grosch · P. Schieberle, Food Chemistry 938
© Springer 2009