PBIO 100 Lecture Notes
Undergraduate Program in Plant Biology, University of Maryland
LECTURE 28 - STIMULATING BEVERAGES
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Importance of trade in stimulating beverages, spices: Greater in age
of discovery than now; fortunes made were comparable to today's fortunes
in defense, computers, software, or cocaine.
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Rationale for stimulating beverages: flavor, feeling of alertness.
Caffeine is active ingredient
in the most popular stimulating beverages. Caffeine is chemically related
to purine bases in DNA.
See its
structure.
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Desirable effects: Stimulation of central nervous system,. faster heartbeat,.
constriction of blood vessels,. increased respiration rate, suppression of
appetite (reason caffeine is in diet pills), diuresis.
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Undesirable effects: headaches on withdrawal, infertility, birth defects,
insomnia: see coffee/caffeine
heath references
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See what caffeine does to and
for humans.
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Caffeine-containing drinks
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Coffee (Coffea arabica):
Terminology about coffee
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A brief review of origin and
history of coffee use.
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Native of eastern Africa; fruits and leaves eaten for stimulation.
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Grown in Yemen;
domesticated, roasting of beans invented, 13th century.
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Coffee brewing spread to
Arabian world in the 16th
century, then
spreads to Europe in the 17th century. Coffeehouses popular throughout
Europe by 1700.
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Center of trade: Mocha, Arabia, in 17th century; Dutch East Indies and Ceylon
in 18th; spread to
French islands
in 18th, Brazil
in 19th, where it had a profound
impact; now most produced in Brazil,
Colombia.
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Additional minor species
of Coffea
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Growing and harvesting
coffee beans: see some
images of coffee
in Colombia
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i. Plant
is a small tree, grows in cool subtropical mountain habitats.
ii. Small fruit is called cherry, contains two seeds called beans; harvested
ripe, by hand.
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Processing
coffee:
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Hull removed, seeds fermented (non-alcoholic) 12-24 hrs, dried 1 week.
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Coffee beans are
roasted; produces flavor, dark brown color.
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Coffee may be
decaffeinated before roasting; caffeine sold for use in medicines, soft
drinks.
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Coffee brewed with hot water or steam.
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Blends & Roasts and
kinds of espresso
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Tea (Camellia
sinensis)
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Importance: More people drink tea than any other stimulating beverage, but
international trade is less than for coffee.
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Origin and history of use
[REQUIRED READING]: China, about 2700 BC, according to legend. Our word China
derived from chai, Russian word for tea. Early to Japan; Portuguese and Dutch
introduced to Europe late 1600s, after coffee. To American colonies; Boston
Tea Party 1773, protest of tea tax.
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Cultivation and growth: Tea is a small tree, but is pruned to a bush.
Youngest
leaves and stem stips are
harvested
by hand.
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Processing:
Green tea: leaves
are steamed, rolled to break cells and release aroma, dried.
Black tea: leaves are
withered, rolled, fermented (non-alcoholic), dried.
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Aroma and flavor from essential oils, additional taste from tannins; stimulating
effect from caffeine and theophylline.
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Caffeine levels vary with the type of tea, black most, oolong intermediate,
green tea least; also length of brewing will determine
the amount of caffeine
in a cup of tea.
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Cocoa
[REQUIRED READING] or
cacao
(Theobroma
cacao) -- See archeological data here!
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Importance: source of cocoa for beverage and chocolate for confectionery
and even known for its
medicinal
use
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Origin and history of use:
used by Aztecs, who made drink of chocolate, vanilla, and chili pepper.
Introduced to Spain by Cortes 1520s; Spanish added sugar. Later to rest of
Europe, but not as popular as coffee or tea; greasy drink due to cocoa butter.
Cocoa butter processed out 19th century, made modern cocoa.
Chocolate
bars also 19th century. Now grown in plantations, leading producers
Singapore, Ivory Coast, Brazil.
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Cultivation and growth: cacao is a
small tree
native to South and Central American tropical forests. Fruit is size and
shape of a small football, borne on trunk.
Fruit harvested by hand, cut open, pulpy seeds.
See this
review; go down the page for cultivation, processing and chemistry
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Processing: Seeds fermented (non-alcoholic) 4-7 days, develops flavor and
dark brown color. Seeds then are dried, polished, roasted, cracked and dehulled
to release nibs (= cotyledons). Nibs are ground to paste, = chocolate liquor;
molded directly for baking chocolate. Remove cocoa butter, get cocoa powder.
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Stimulating effect from theobromine, chemically related to caffeine.
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Cola drinks: from
seeds
of kola tree
(Cola
acuminata) from West Africa. Seeds fermented (non-alcoholic), dried,
ground. Contains caffeine.
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Coca Cola: Invented 1886, extract of coca leaves and cola seeds; coca extract
contained cocaine, later removed, but Coca Cola still contains rest of coca
extract.
Other Sites of Interest:
Seeds of Change Garden
General coffee
information
Coffee
and Agriculture in the Americas
The world of tea
History of the teapot
Chinese tea
ceremony
Japanese tea
ceremony
Mexican
chocolate: The original stuff
"Where chocolate grows on
trees" by Carby Kummer; from The Atlantic Monthly
"Chocolate
assignment" by Kate: A good review!
McCormick
Spice Chart
The following treatments were prepared by James A. Duke