To All,
Coffee and tea guru William H. Ukers [p. xi] states, "Civilization in its onward march has produced only three important non-alcoholic beverages--the extract of the tea plant, the extract of the cocoa bean, and the extract of the coffee bean." Cocoa is covered in the e-mail of 16 May 2015 and coffee in this e-mail. The next e-mail in the "Fruit Behind the Foodstuffs" series treats tea.
The Coffee Plant
Coffee is in the family Rubiaceae, which is often called the bedstraw family. Common plants in New England in this family include buttonbush, bluets, partridgeberry, wild madder, cleavers, and various bedstraws; the cinchona tree, from which we derive quinine, is also in this family. Two species of coffee are grown commercially. Coffea arabica, called arabica, is the standard coffee that accounts for 75-80 percent of world production and Coffea canefora, called robusta, for about 20 percent. (There is very minor cultivation of two other species [Weinberg and Bealer, p. 240].) The map below shows where these two species are grown; the yellow shows where arabica is grown, the dark green where robusta is grown, and the light green where a mixture of arabica and robusta is grown.
This e-mail uses coffee to refer generically to both species, and this term is also used to refer to the plant, berry, bean, and beverage. The main differences between these two species are shown in the graphics below and can be summarized [Pendergrast, p. 42]:
- Arabica is lighter and is usually thought to be more flavorful while robusta has more body and is more bitter. As one expert expressed it, "...even the best robusta brew tasted harsh, flat, and bitter" [Pendergrast, p. 141]. Robusta is used in espresso to provide a stronger taste and a better head of foam [Pendergrast, p. 94]. Also, robusta beans can be used in instant coffee, which tastes so bad that it doesn't matter much what type of bean is used [Pendergrast, p. 219].
- Arabica grows at higher altitudes and drier conditions while robusta grows at lower altitudes and moister conditions. Also, robusta can grow in a wider variety of soil conditions [Weinberg and Bealer, p. 244]
- Arabica is highly susceptible to coffee rust, a disease that is present everywhere and can destroy coffee plantations in entire regions, e.g., it effectively ended coffee growing in Ceylon after 1869. Robusta is resistant to coffee rust.
- A robusta plant yields more berries, and it is easier to pick since, unlike arabica, the berries stay on the tree when ripe rather than falling to the ground [Weinberg and Bealer, p. 244].
- Robusta has twice as much caffeine as arabica.
- Robusta has a smaller cost of production for the reasons given above (disease-resistant, more productive, easier to harvest) [Weinberg and Bealer, p. 244].
The coffee plant is an evergreen bush or small tree that typically grows to a height of 10-12 feet, though farmers usually trim it to about six feet or less to keep it short enough for easy harvesting, as shown in the pictures below [Ukers, p. 133, Weinberg and Bealer, p. 243]; this e-mail follows the conventional usage and calls it a tree. In the wild it is a plant of the understory. The best arabica coffee grows at higher elevations in the shade since this allows the berries to mature more slowly and develop a better flavor [Pendergrast, p. 25]. Coffee does not tolerate freezing temperatures. The first picture shows a coffee plantation in Brazil, the next two show coffee orchards, and the last shows coffee seedlings.
Clusters of axillary white flowers bloom simultaneously. ("Axillary" means that the flowers are in the angle between the branch and the leaf stem. You can see this especially clearly in the tattoo below.) The flowers are about an inch wide and are heavily scented and said to smell like jasmine. As you can see in the pictures, the flowers can be very dense; overflowering, which can lead to an inferior harvest and decreased yield the following year, is dealt with by pruning. The mass flowering can be breath-taking, but, like so many human pleasures, it is fleeting and is gone in a couple of days [Ukers, p. 135].
After the flowers are fertilized, the berries appear. Flowers that open on a dry, sunny day will produce many more berries than those that open on a wet day since the pollinators are more active on sunny days [Weinberg and Bealer, p. 243]. (The berries are often called "cherries," but that usage will not be followed here since I refuse to devalue this term by overuse.) The berries are at first green and as they ripen they turn yellow and then red. A berry is close to half an inch in diameter when ripe. When dried, they are black. Most berries contains two seeds, which are called coffee beans. It takes the berries about nine months to ripen. The last picture shows the pulp around the two berries.
Wikipedia summarizes the reproductive biology of coffee:
Coffea arabica is predominantly self-pollinating, and as a result the seedlings are generally uniform and vary little from their parents. In contrast, Coffea canephora, and C. liberica are self-incompatible and require outcrossing. This means that useful forms and hybrids must be propagated vegetatively. Cuttings, grafting, and budding are the usual methods of vegetative propagation. On the other hand, there is great scope for experimentation in search of potential new strains. [Footnotes and links omitted]
If an arabica seed is planted, it will start producing a crop in five or six years, and the productive life of the plant is about thirty years. The usual, and much cheaper, method of propagation is to use a cutting of an upright branch of a coffee tree; it will readily take root and produce a new tree. Sometimes coffee tree wood used as fence posts will start growing [Ukers, p. 138]. A robusta plant will start producing in the second year [Pendergrast, p. 141].
The wood of the coffee tree is very strong, and the superannuated coffee trees, in addition to being used as fence posts, are often used for cabinets [Ukers, p. 138].
[Continued in Part 2]
