Where does coffee come from? How is it processed? How does it fit into human culture?
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Where does coffee come from? How is it processed? How does it fit into human culture?
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David follows a coffee bean from plantation to mug.
Segment length: 6:00
It's been used as a medicine and an ingredient in wine. It's been linked with
revolutionary ideas. First a food, later a beverage, coffee contributed
significantly to the economic health of countries that controlled it. The
coffeehouses in the Middle East and Europe that sprang up because of it became
centers of intellectual ferment, often frowned upon by the authorities.
Native to Ethiopia, this crop is now grown around the world and is a major commodity in the world economy. The principal species, Coffea arabica, thrives at high elevations in a moist, mild climate where there is partial shade. That's why most of the big coffee producers are located in mountainous countries near the equator.
The coffee tree is a shrublike plant with glossy, dark-green leaves and small, white, fragrant flowers. The fruit, or cherry, is initially green and gradually ripens to a dark red. Although people used to eat the coffee cherries or chew the coffee leaves, the principal interest now is in the coffee seeds or beans.
Removal of the fruit from the beans requires several steps and considerable water because the inner part of the fruit is so sticky. Processors first pulp and wash the cherries, and then allow them to ferment before washing them again. During fermentation, microorganisms act on the sticky inner layer of the cherry to break it down. Finally, the seeds are dried, and a hulling machine crushes the remaining parchment covering so it can be removed. The seeds-now called green coffee beans-can be roasted in several different ways.
To prepare coffee, people brew the ground-roasted beans with hot water, a process that extracts flavor and fragrance chemicals. Only those chemicals that are soluble in hot water dissolve to make the coffee. The coffee grounds are left behind. One chemical naturally present in coffee is caffeine, which is a mild stimulant. But many different chemicals are manufactured by the coffee plant, and other chemicals are created in the roasting process.
Most coffee flavor comes from roasting-green coffee beans smell and taste completely different from roasted ones. Caffeine can be extracted from the beans to make decaffeinated coffee without altering the flavor much, since caffeine itself has very little flavor.
Connections
1. If you were a farmer, what things would you consider before growing coffee
for sale? What plans would you have to make?
2. What are the known effects of caffeine on the human body? Is caffeine
addictive? Are there medicinal uses for it? Do soft drinks with caffeine sell
better than those without?
brewing hot-water extraction of flavors, fragrances, and caffeine from
ground-roasted coffee beans
commodity any object or material that is bought and sold
economic botany the study of plants bought, sold, traded, or otherwise involved
in a society's commerce
fermentation in coffee processing, the action of microorganisms on the sticky
inner pulp of coffee cherries
hulling removal of the dry parchment layer on coffee beans after they have been
pulped, fermented, washed, and dried
pulping mashing coffee cherries to loosen the fruit pulp so it can be washed
away
roasting heating green coffee beans in hot air to brown them and develop the
distinctive aroma and flavor of coffee
National Coffee Association
110 Wall Street
New York, NY 10005
(Free history booklets on coffee-requests in writing only.)
Flavors and fragrances play a large part in our daily lives. We add spices to food to make it taste and smell good, and put perfume on ourselves to make us more attractive. We tend to avoid unpleasant odors. Most flavors and fragrances are not single chemicals but mixtures of several substances. Coffee is usually blended from various types of beans to obtain a pleasant taste. Experienced coffee tasters can tell where specific kinds of coffee come from just by taste.
Flavor and fragrance experts talk about "notes" of scent-fruity,
flowery, aromatic, earthy, musky, and so on. Some odors are unpleasant in large
amounts, but smell good in small amounts or when mixed with other scents. Coffee,
for example, contains sulfur compounds that are unpleasant by themselves, but
that smell pleasant in the aroma of coffee. Most perfumes are specific blends of
fragrance notes.
Materials
Many foods and drinks contain caffeine. Find out what they are and add up your
daily caffeine consumption.
Too much caffeine makes people jittery and irritable. In larger quantities it can
be poisonous. Decaffeination removes the caffeine from coffee and other
beverages. One type uses carbon dioxide under so much pressure that it becomes a
semi-liquid called a supercritical fluid. Find out about other decaffeination
processes. How will you plan your research?
Try your hand at economic botany. By studying back issues of the Wall Street
Journal, Business Week, or other financial publications, track the weather in
Brazil and the price of coffee. Can you graph these two things on a yearly or
semi-annual basis? Does there seem to be a relationship between weather and
price? What other environmental events might influence the price of coffee or
other commodities?
A fruit is the enlarged ovary of a flowering plant, and it encloses the seeds
from which a new plant can grow. Coffee cherries are fruits, and fruits all have
some similarities. Dissect several fresh fruits. How are they different? How are
they similar? Could you tell plants apart based entirely on their fruits?
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Made possible by a grant from 3M.
Educational materials developed with the National Science Teachers
Association.
