They are: coffee, tea, chocolate and certain soft drink

1
Stimulant Beverages There are only a few commonly
consumed beverages that have a stimulant effect.
They are coffee, tea, chocolate and certain soft
drinks like Coca Cola. What do they have in
common that makes them stimulants? Caffeine (and
other alkaloids that differ among plants) all
are stimulants to the mammalian CNS. They are
collectively called secondary chemicals. This
means plants produce them as offshoots/slight
modifications to normal metabolism. The most
likely function for these chemicals is to act
against herbivores.
2

• Caffeine is rapidly absorbed from the stomach and
  small intestine (within 45 minutes of ingestion),
  and distributed throughout the body by the
  circulatory system. It has effects on many
  systems
• In the liver it is metabolized by the same enzyme
  system that works on organic pollutants, the P450
  system. There are three metabolites produced by
  that metabolism
• Paraxanthine increases glycerol and fatty acid
  levels in
• circulation
• 2. Theophylline relaxes smooth muscles,
  particularly in the bronchi. In higher doses than
  you can get from beverages it can be used as an
  asthma treatment.
• 3. Theobromine same stuff as in chocolate.
  Dilates blood vessels and acts as a weak diuretic.

3
Caffeine also crosses the blood-brain barrier,
and its structural similarity to adenosine seems
to cause a number of other effects.
4
Those effects include Blocking adenosine
receptors, which in turn results in increased
activity of dopamine. This is the root cause of
the stimulating effect. Increases in serotonin
levels that improve mood. An increase in
epinephrine, the adrenal hormone involved in
flight-or-fight responses. It stimulates the
sympathetic nervous system, resulting in
increased heart rate, blood pressure, and blood
flow to the muscles. It blocks cyclic nucleotide
phosphodiesterase, resulting in increased levels
of cyclic AMP. That prolongs the effects of
epinephrine.
5
Caffeine is believed to lower the chances of
getting Parkinsons disease (in men in women the
result is uncertain), and may also lower the
probability of becoming type II
diabetic. Caffeine is a sufficient stimulant of
physical performance (7 increase in work output,
19 increase in exercise endurance) that the IOC
has set a urinary output threshold. The IOC limit
is 12 ?g/ml urine that would be the result of
consuming 8 cups of coffee in 2-3 hours. The U.S.
NCAA has set its limit at 15 ?g/ml urine.
6
All that sounds relatively positive. However,
there are also negative effects One can
habituate to caffeine, but in occasional
consumers (2-3 cups of coffee per day)
consumption of gt250 mg typically results in
headaches, nervousness, irritability, anxiety,
and even muscle twitching. There are even names
for these diseases caffeinism when the
caffeine comes from coffee drinking, theism when
the source of caffeine is tea. Habitual users
have the opposite problem withdrawal symptoms.
Abstinence for more than a day results in
headache, irritability, insomnia, and dysphoria
(the opposite of euphoria). Long-term
overconsumption (15 cups of coffee or more per
day) can have serious consequences, including
heart attack.
7
Other negatives Caffeine consumption is
associated with birth defects and with
infertility in women. Caffeine can exacerbate
heart problems through causing increased level
and persistence of epinephrine and
vaso-constriction raising blood pressure. (Note
the opposite effects of some caffeine metabolites
with respect to smooth muscle and blood
pressure!) Caffeine is addictive, with more rapid
recovery from withdrawal symptoms than with drug
addiction, but many of the same problems during
withdrawal.
8
How much caffeine do we get from some of our
favorite beverages? Beverage Caffeine per
serving (mg) Brewed coffee 135 Excedrin
tablet 65 Expresso coffee 100 Chocolate
(dark, 1.5oz bar) 31 Red Bull 80 Jolt
Cola 150 Mountain Dew 54.5 Coca Cola
34 Tea (leaf or bag) 50
9
Now, what are the plants, the sources and current
production of coffee and tea? Coffee Coffee is
made by roasting, grinding, and brewing the seeds
of Coffea arabica (Rubiaceae) mostly. The drink
and use of the seeds can be traced back to the
Ethiopian highlands in the 9th century. There are
other species of Coffea, but only one, with more
caffeine but inferior flavor, is grown
commercially C. robusta. Originally the coffee
berries (beans) were eaten raw and whole. Later
they were crushed with fat and eaten as a food.
10
Coffee was spread from Ethiopia into the Middle
East by the 13th century. By then coffee beans
were roasted much like today. By 1500 coffee was
widely cultivated in Yemen, and had been carried
to southern Asia (particularly Sri Lanka and
Java). It became an important social drink in
coffeehouses. The muslim Imams did not approve of
coffeehouses, but their popularity prevented
forcing closure. The name mocha comes from the
Yemeni port from which beans were exported. The
name java similarly arises from an early
important source of beans. Coffee was imported to
Europe by traders in 1615. By 1700 there were
coffeehouses spread over Europe. They were, much
like in the 1960s, centers of art, culture,
political debate and discussion Lloyds of
London began from insurance underwriters meeting
in a dockside coffeehouse.
11
There were coffee plantations in South America by
1720, and a North American coffeehouse in Boston
(using beans imported from Europe) in 1669.
Coffee was initially not as popular in North
America as in Europe. However, as the British
reduced access to and taxed tea (resulting in the
Boston tea party), coffee consumption
grew. Today both species of coffee are grown.
Cheaper C. robusta beans caused a major global
economic dislocation. C. robusta trees (really
evergreen bushes) are more tolerant of (and
actually like) bright light conditions, and can
be grown in open plantations where machine
harvesting is possible. It is more
disease-resistant.
12
Less efficient hand harvesting and tree/bush
management of shade-grown C. arabica led to small
coffee growers abandoning their plantations
world price did not meet cost of production for
them. Now you can find Fair Trade coffee.
Growth also requires year round rain, total
precipitation of 1 1.5 m, and a temperature not
varying much from 20C. C. arabica accounts for
about 75 of the worlds commercial coffee
crop. The leading producers (2007)
are Brazil 17 million metric tons (C. arabica
) Vietnam 15.6 (C.
robusta) Columbia 9.4 (C.
arabica) Indonesia 2.8
(C. arabica )
13
rCoffea canephoramCoffea canephora and Coffea
arabicaaCoffea arabica
Structure of coffee berry and beans 1 center
cut 2bean (endosperm) 3 silver skin (testa,
epidermis), 4 parchment (hull, endocarp) 5
pectin layer 6 pulp (mesocarp) 7 outer skin
(pericarp, exocarp)
The red berry is the fruit. Each fruit contains
two seeds (beans) with their flat sides
oriented towards each other. It takes about 7
years for a coffee tree to mature and produce
fruit. Growth is optimum between 1,300 and 1,500
m altitude, but some coffee is grown from sea
level to 2,800 m.
14
Since the flavor of coffee is very dependent on
harvest at exact ripeness, most high quality
(arabica) coffee is still picked by hand. Coffee
production in some places (Sri Lanka, Indonesia,
Africa) has been limited by a fungal rust
(Hemileia vastatrix). C. robusta is resistant.
Sri Lanka was so affected that it shifted from
coffee to tea production. Production of arabica
beans is limited to areas that have never been
infested with the rust. Harvested beans are
first de-pulped to extract the beans. In the
Americas this is done by the wet method. Fruits
are floated in tanks to remove other debris, then
mechanically de-pulped. Pulp remaining is allowed
to ferment for a day. Beans are washed and dried,
and seed coats are mechanically removed. Beans
are then roasted.
15
In the dry method used in Africa, fruits are
spread in the open and allowed to dry for days.
The pulp ferments, then the pulp is removed
mechanically, and the beans can be
roasted. Roasting The roasting process produces
the flavor and aroma of coffee. The end points of
roasting are light roasts (beans look pale to
chocolate brown) at 212-218C producing a milder
coffee with more caffeine to dark roasts
(French black and expresso, beans come out black)
at 240 -250C producing stronger and typically
more bitter coffee.
Expresso roast
16
Roasting turns starches into sugars in the beans,
then, at the final roasting temperature
carmelizes the sugars. At just below 240C sugars
are burned to carbon. Thus lighter roasts only
carmelize the sugars, while expresso roasts
carbonize them. The oils that give coffee aroma
are also driven out of cells to the surface of
the beans by roasting. Unroasted beans can be
stored for extended periods without detriment.
Roasted beans only have a shelf life of somewhat
more than one month. Thats the reason quality
coffee beans are vacuum packed. However, roasted
beans cannot be immediately vacuum packed they
emit CO2 for a few days after roasting, and
packing has to be delayed.
17
Ground coffee has a shelf life of no more than a
few days. Grind it just before brewing if you
can. Refrigerate (or even freeze) ground coffee
to retain as much of the flavor as possible.
18
Processed coffees Instant coffee was developed in
1901 by Satori Kato, a Japanese chemist working
in Chicago. During WW I the U.S. found the light
shipping weight and rapid preparation a great
advantage, and shipped it to the troops. However,
it was not an instant hit. Nescafé finally
launched commercial instant coffee in
1938. Production usually lower quality, cheaper
beans are used. After roasting and grinding,
coffee is brewed by percolation through columns
at gt300F. This coffee is concentrated (15 30
coffee solids). It is then dried to crystals by
either spraying (spray drying, evaporating the
water) or freeze drying (wet coffee is frozen,
then placed in a vacuum chamber water
evaporates, leaving coffee crystals).
19
This is one granule of freeze dried coffee. The
large pits are what remains of air bubbles, left
when the air is removed in vacuum.
20
Decaffeination Caffeine is removed from
unroasted, green coffee beans. The first version
of the process was developed by German chemists
Ludwig Roselius and Karl Wimmer in 1903. Beans
were steamed in salt water brine, then caffeine
was extracted using benzene as the solvent.
Decaffeinated coffee made this way was sold as
Sanka brand. Benzene is now recognized as a
carcinogen. It is no longer used as the solvent.
Now methylene chloride (banned in hairspray as a
carcinogen) and ethyl acetate are used. After
steaming, beans are soaked in these solvents for
10 hours, then steamed again for 10 hours to
remove any residual solvent.
21
An alternative is Swiss water decaffeination.
Beans are soaked in hot water until all the
coffee flavors and caffeine are released. Beans
are discarded, and the water and coffee solids
pass through carbon filters that absorb the
caffeine. This water is then used to extract
caffeine from beans without losing flavor. The
soaking in flavor-charged water can be repeated
until gt99 of caffeine has been removed. However
from Dr. Crosby a comedian/musician named Bob
Irwin apparently said drinking decaffeinated
coffee is like kissing your sister/brother.
Make your own decisions about caffeine
22
Tea Tea is a beverage brewed by steeping
processed leaves, twigs, and/or buds of plants.
What we usually mean by tea is brewed using
leaves of Camellia sinensis Theasceae. The
various types of tea are determined by how the
leaves are processed. After the leaves are picked
they begin to wilt and oxidize. The leaves darken
because chlorophyll breaks down and tannins are
released. The tea industry calls this
fermentation, though it is not biological
fermentation (no microbes involved). The process
is stopped at different stages to produce the
varieties of tea.
23

• White tea produced from young buds with
  oxidation
• prevented. Buds are shielded from sunlight to
  prevent chlorophyll formation.
• 2. Green tea oxidation is stopped very early,
  either with steam (Japanese method) or dry
  cooking in pans (Chinese method).
• 3. Oolong tea oxidation is allowed to continue
  for 2 3 days. The process is then stopped and
  the leaves further processed.
• 4. Black (or red) tea the oxidation process is
  allowed to continue for 2 weeks to one month. The
  leaves turn black, but the liquid tea is reddish.
• 5. Kukicha (or winter) tea made from twigs and
  old leaves pruned during the dormant season and
  dry roasted over fire.

24
The small tips of oolong tea leaves are what make
up Orange Pekoe tea. Jasmine tea is made by
adding dried Jasmine flowers to the tea. Earl
Grey tea has been infused with bergamot
oil. Herbal teas generally have no tea leaves.
Instead they have various plant parts replacing
tea leaves, e.g. rose hip or chamomile. Tea bags
are made with the broken leaves of the various
varieties of tea.
25
About 3 of the dry weight of tea is caffeine.
Tea also contains catechins (antioxidants, up to
30 of dry weight), with a much larger content in
white and green teas than in oolong or black tea.
It also has both theobromine and
theophylline. The cradle of the tea plant is a
region that encompasses eastern and southern
China, northern Myanmar, and Assam in
northeastern India. The variant sinensis grows
naturally in eastern and southeastern regions of
China. China is the first place where tea
drinking was recorded, dating back to 2737 BC,
when a tea leaf accidentally fell into water
being boiled for drinking. Green tea was drunk in
Japan at least as early as 900 AD. Tea reached
Europe in the second half of the 16th century.
26
Tea had become popular in the American colonies
by the mid-1700s. In the colonies much more tea
was consumed than coffee. The British passes the
Tea Act in 1773. It was not a new tax on tea,
rather it was an act to allow the British East
India Company to avoid a colonial tax on tea, and
therefore undercut colonial merchants who had to
pay the tax. That led to the Boston Tea Party,
when the Sons of Liberty, dressed as Native
Americans, dumped 342 crates of British East
India tea into Boston Harbor. The tide was out,
and many of the crates actually stood out above
the water. Retaliatory measures the British took
led to the American Rebellion.
27
Camellia sinensis is an evergreen plant and grows
in tropical to sub-tropical climates. In addition
to tropical climates (at least 50 inches
slightly less than 1½ m of rainfall a year), it
also prefers acidic soils. Many high quality tea
plants grow at elevations up to 5,000 feet (1524
meters), as the plants grow more slowly and
acquire a better flavor. Only the top 1-2 inches
(tip leaves) of the mature plant are picked. Tea
production China 800,000 tons India 820,000
tons Kenya 328,000 tons Sri Lanka 309,000
tons Turkey 205,500 tons Global total 3.2
million tons
28
Health effects of tea The catechins in green and
white tea may have antibiotic effects, resulting
from disrupting bacterial DNA replication. Green
tea has been reported to reduce growth rate of
breast cancer (controversially, the FDA says the
evidence is insufficient). The only
experimentally documented effect on cancer
derives from the presence of a catechin
(epigallocatechin gallate) that affects a lung
cancer cell binding site and evidence that the
same binding protein may be important in prion
disease (Creuzfelt-Jacob/mad cow). Green tea may
improve insulin sensitivity (of value in treating
type II diabetes), and may even help prevent the
occurrence of diabetes.
29
Theanine (from tea leaves) seems to boost immune
response when fighting a disease coffee does
not have this effect. Immediately after stress
the stress hormone cortisol declines back to near
normal levels more rapidly in regular drinkers of
black tea (no info about other types of tea).
These same subjects had lower levels of blood
platelet activation, which should reduce the
probability of cardiac thrombosis. Drinking 3
cups or more of tea per day is apparently
associated with decreased risk of stroke and
cardiovascular disease. There are some negatives
remember that tea contains caffeine. Drinking
enough tea to gain some of those benefits may
also expose you to risks of excess caffeine
consumption.
30
Tea leaves contain oxalates. If you drink a lot
of tea, the oxalates (in low amounts in general)
can bind calcium and can cause kidney stones.
31
Kola drinks The seeds of the Kola tree (Cola
nitida) are the basic flavor source. The tree is
native to West Africa (Sierra Leone and around
the Niger delta), and related to the cacao tree.
It is now cultivated in the West Indies, Brazil
and Java, as well. The cola nut is the source of
caffeine in these beverages.
32
A little history Coca Cola was invented by John
S. Pemberton in Atlanta in 1885. Originally it
was a cocawine, but re-formulated into coca
cola at the outset of prohibition. The first
recipes used fresh coca leaves, and contained 9
mg of cocaine per glass. Later, the recipe called
for spent leaves from which the cocaine had
already been extracted. Other ingredients Kola
seed extract, caramel, high fructose corn syrup,
vanilla, cinnamon, lime juice and orange oil. The
U.S. Federal government allows one farm in New
Jersey to grow Coca plants for production of Coca
Cola. There have been a number of legal and
political shenanigans associated with who owns
and controls cokes formula. Asa Griggs Candler,
who founded what is now Coca Cola, apparently
forged at least two signatures to take control of
the formula the inventor Pembertons and
Margaret Dozier.
33
The original recipe is held in the Sun Trust bank
vault in Atlanta, and is a closely guarded
industrial secret. Its held there because Sun
Trusts predecessor was the underwriter for Coca
Colas initial public stock offering. Myth (??)
has it that only two executives have access, and
each to only half the formula.