Introduction Many plant materials are used for beverages. For example, the juices of many fruits are drunk. Popular beverage plants include roselle or flor jamaica or roselle (Hibiscus sabdariffa, Malvaceae), rooibos tea (Aspalathus linearis, Fabaceae), tamarind (Tamarindus indica, Fabaceae), and a number of herbal teas.
Roselle or flor jamaica, Hibiscus sabdariffa, Malvaceae
Field of rooibos in South Africa B. E. van Wyk and N. Gericke, People’s Plants, Briza, Pretoria, 2000
Stimulating beverages However, coffee, tea, cacao, and other stimulant-containing beverages are extremely popular and widely consumed. Interestingly, the history of use of these plants among most Europeans only dates to the 1500s and 1600s.
Tea and coffee are consumed daily by at least 1/3 of the world's population. Table of beverages and the compounds they contain p. 314. Also see table on page 317. Many of the beverages we drink contain caffeine. These give the consumer a general feeling of well being. One of these beverages is consumed by most people in the world on a daily basis.
Coffee, Coffea arabica or C. canephora (Rubiaceae) The dried, fermented fruits of Coffea arabica or C. canephora (Rubiaceae) are second only to petroleum in the value of the material traded annually on the international market. See coffee diagram on p. 317.
Coffee plantation in Venezuela. Note the legume shade trees.
Mature coffee in Kenya Courtesy Dr. Abraham Krikorian
Drying coffee in Kenya Courtesy Dr. Abraham Krikorian
Coffee has up to 3% caffeine by weight. Coffee probably originated in Ethiopia. The leaves, which also contain caffeine, were originally chewed. At some point, however, people started using the fruits. The plant was taken to the Arabian peninsula about the 6th century. The Arabs were the first to "brew coffee".
Coffee drinking didn't spread to Europe until the 1600's. This beverage became an important aspect of social and political development in England about 1650. There were 3000 coffee houses in 1675; these institutions served as forums for political and religious debate. The king tried to have them closed, but was not very successful.
The Arabs monopolized the coffee trade. They killed the seeds before marketing them. Eventually, however, the Dutch acquired live seeds from Mocha, the traditional source of Arabic coffee. They started plantations in Sri Lanka and the East Indies and broke the Arab monopoly.
Coffee was taken to the West Indies about 1723. From a tree taken from Paris to Martinique in 1723, coffee spread through the western hemisphere. Brazil leads the world in coffee production.
Coffea arabica accounts for about 90% of world's trade in coffee. Importantly, the coffee from Coffea arabica has the best flavor. C. arabica is a self-compatible polyploid. Coffea canephora accounts for another 9%. C. liberica accounts for about 1%. Both are more productive and more disease resistant. Coffea canephora and C. liberica are self- incompatible diploids. C. canephora is used often to make instant coffee. This species is preferred in some parts of Africa.
The fruit of coffee is a type of berry (inferior ovary). The seeds are removed from the fruits and are the part used to prepare the beverage. Coffee fruits are often called "beans". Coffee is usually cultivated in tropical and subtropical latitudes. It prefers rich soils and high rainfall, with a seasonally dry period. A plant produces fruit after 3 years and until the plant is about 40 years old.
The plants are often shaded in plantations, but open orchards are used as well. Many of the shade trees are legumes and fix nitrogen. The best coffee usually comes from areas with cool nights. Coffee is seldom harvested mechanically. The best coffee comes from berries picked just when ripe.
The seeds are separated from the outer portion of the fruit by either a wet or dry process. In the dry process, the fruits are dried and the outer portion abraded away. See diagrams p. 319 and 321. In the wet process, the fruits are depulped by a machine and the seeds washed.
The wet seeds are allowed to ferment for 12-24 hours. After fermentation, the seeds are dried for about a week. The remaining endocarp and the seed coats are removed mechanically. Roasting is also essential to development of flavor of the final product. The temperature and time of roasting are important.
In recent years instant and freeze dried coffee have become extremely popular and account for a large part of the market. Much instant coffee is made by flash drying. "Aroma components" are added to give the product enhanced flavor and odor.
Decaffeinated coffee is also important. In 1981, this form of the beverage accounted for about 17% of the coffee drunk in the U.S. The caffeine is removed from green coffee beans by solvent extraction, water extraction, or steam extraction. Methylene chloride is often used as the extraction solvent.
There are many serious disease problems with coffee. These have made it difficult to grow Coffea arabica in many parts of Africa and these diseases now have been introduced into Brazil.
Cacao, Theobroma cacao (Malvaceae) (formerly Sterculiaceae) Cacao is native to the Americas. Although considered as a beverage in this lecture, eating chocolate is more important than the beverage today. The plant, Theobroma cacao is a small tree. Cacao was a quite different beverage to the Indians of Central America than it is to us today. See diagram p. 325.
Cacao flowers, Theobroma cacao, Malvaceae Courtesy Axel Walther
Cacao fruits, Theobroma cacao, Malvaceae Courtesy Axel Walther
Cacao fruit, Theobroma cacao, Malvaceae Courtesy Axel Walther
When Columbus and his men landed in Nicaragua, they reported seeing the Indians drinking a strange beverage. Cortez reported on the importance of cacao in the Aztec court. Quetzlcoatl gave cacao to the Indians. Cacao was cultivated in Mexico by about the 7th century.
The beans were roasted and mixed with ground achiote, Bixa orellana (Bixaceae). Red pepper was also added. The whole mixture was cooked into a paste and made into tablets. The drink was made by putting these tablets into water. This beverage was often thickened by adding atole.
Not surprisingly, Europeans didn't like this drink too much. They added sugar and left out the chili peppers. In the middle 1600's, chocolate drinks were extremely popular in Europe. The Spanish had a monopoly on the chocolate trade. The Dutch broke the Spanish monopoly by establishing plantations in southeast Asia in 1670. Cacao was introduced into Africa in 1878 and today most cacao is produced in Africa.
The pods are harvested, opened, and the seeds and pulp removed. The seeds are allowed to ferment for 4 to 7 days. Water loss causes them to shrink from the seed coats. See diagram p. 325. The pulp is liquified by microbes, and the seeds inside are then dried and polished. Subsequently, the seeds are shipped.
Cacao seeds undergoing fermentation Courtesy Axel Walther
As for coffee, roasting is an important part of development of cacao flavor. The chocolate flavor only develops during this part of the processing. The seed coats are removed. The seed coats and seeds can be extracted to produce a lipid known as cocoa butter (about 30% of the cotyledons). This substance is used in other food products and in pharmaceuticals. The seeds contain theobromine, a compound with similar properties to caffeine.
Chocolate is made by making the nibs or cotyledons into a paste. In the Dutch process, the cocoa butter is separated and dry cocoa powder produced. The acids are neutralized with alkalai. About 90% of all cocoa is produced this way. The English devised adding milk to cocoa as a beverage. The Swiss started adding milk to the cocoa to make milk chocolate. Cocoa butter is re- added to make the product more creamy.
Tea, Camellia sinensis, Theaceae Tea is drunk by a larger number of people than coffee, but does not have as high dollar value. Most tea is consumed locally and comparatively small quantities enter international trade.
The exact origin of tea, Camellia sinensis (Theaceae), is obscure, but the plant appears to have arisen in China. The first book on tea was written in 780 B.C. Tea came to Japan in 593 B.C. The Mongols got tea from the Chinese and traded it across Asia. The Russians got tea in this way.
Tea plantations and harvesting in Kenya (upper) and Indonesia (lower) Courtesy Dr. Abraham Krikorian
Tea harvesting in Sri Lanka Courtesy Dr. Guido Holzkamp
Europeans first got into tea when the Portuguese brought it back from China. In the 1700's tea had become an important item of trade. Both the British and Dutch bought tea in the Orient and sold it in Europe. People drank tea predominately in the English colonies in America until the Boston Tea Party; then coffee became a more popular beverage. Tea is of course still very popular in England.
The British started planting tea in India about 1818. Sri Lanka has been the second most important tea producer, but tea production there only started after the coffee rust wiped out coffee in 1880. Because of the hand labor, tea is not grown extensively in the U.S. or most other countries in the Western Hemisphere (some is grown in Argentina).
The plants are evergreen; they require lots of rainfall and a constant cool temperature. Only the two or three youngest leaves are used for good quality tea. For green tea the leaves are dried fairly quickly to stop most enzyme activity.
For black teas, the leaves are allowed to wither, and rolled or twisted (broken) and then allowed to ferment for several hours. This modifies the tannins and polyphenols in the leaves. The tea is then fired or heated to stop further enzyme action. Oolong teas are semifermented. See outline of tea manufacture p. 329.
Tea leaves moving into processing area and a tea “breaking” machine Courtesy Dr. Guido Holzkamp
Tea ovens and tea grading machine Courtesy Dr. Guido Holzkamp
Yerba maté (Ilex paraguayensis, Aquifoliaceae) Maté is a common beverage of southern South America. The Indians of much of South America used maté at one time. As it true for tea, the leaves of yerba maté are used. The leaves and small twigs are heated over a fire and then allowed to stand for a period of time. The leaves, small twigs, and stems are crushed and used to make a tea like beverage.
Maté is traditionally drunk from a gourd, or maté, filled with plant material. Hot water is added. The "straw" is called a bombilla.
Ilex vomitoria, native to the southeastern U.S. was used to prepare “black drink” and used ceremonially by Indians of the Southeastern U.S.
The seeds of Paullinia cupana (Sapindaceae) are used to make a beverage called guaraná. This plant was originally from the Amazonian region of Brazil. Guaraná is rich in caffeine. The ground seeds are made into a paste that sets up like a brick. Guaraná, Paullinia cupana (Sapindaceae)
Guaraná, Paullinia cupana, Sapindaceae R. Bentley and H. Trimen, Medicinal Plants, London, Churchill, 1880.
A small amount of this material is rasped off and mixed with hot water to make the beverage guaraná. Guaraná is second only to coffee as the most popular drink in Brazil. A soft drink prepared with this material is similar to cola flavors.
Kola, a relative of cacao (Cola nitida, Sterculiaceae) is used to prepare the flavor of cola beverages. The seeds of the plant are also fermented in the manufacture of the flavoring. Cola is native to West Africa where it has been used for a long time. Kola, (Cola nitida, Sterculiaceae)