Table of content A-Z




Botanical name: Coffea



Coffee was originally native to Africa, more precisely to Ethiopia. It has been used by the Arabs as a crop plant since the 15th century. In the 18th century, drinking coffee became popular in Europe, and new growing areas were needed to meet the demand for coffee beans. The French, for example, therefore brought coffee to the Caribbean and cultivated it there.


Because coffee can be grown in tropical and subtropical regions it is meanwhile cultivated in over 50 countries of the world.


The variety most frequently grown is Arabica (Coffea arabica), also known as mountain coffee. Arabica is the first wild-growing variety and the first to be specifically cultivated. It constitutes about 70% of the world harvest. Another variety is Robusta, with about a 25% share of the world market. It is also known as Congo coffee, because it originated there.


Today, approximately two thirds of all coffee beans come from South and Central America. Imported beans sold in Germany come chiefly from Colombia, Brazil, El Salvador, Indonesia, Kenya, Tanzania and Papua New Guinea.



We differentiate between highland and lowland coffees, highland coffee having a higher quality. The harvest can take several months, because of its long blooming period.


For the end-consumer, coffee is available all year round, roasted as well as in numerous products from the food industry.


Appearance, taste, characteristics

The tree on which the coffee beans grow can be up to 4.5 m tall. As a rule it is kept shorter to facilitate the harvest. The tree's white blossoms have a scent resembling that of jasmine. After 3-5 years a tree has the optimal yield.


Coffee berries or cherries are green at the beginning and turn red as they ripen; they are harvested by hand. Inside are usually two greenish seeds 3-17 mm long. When the berry contains only one round seed we speak of pearl coffee.


After being harvested, the beans are freed of the surrounding pulp, either by being dried or by moisture treatment. The latter is the more sparing process, by which the pulp is fermented and the beans are not exposed to any heat. Subsequently, the parchment shell and the silver membrane are removed, leaving just the bare bean. The beans are filled into sacks to be exported; they are not sorted and roasted until they reach the country where they will be consumed.



A coffee bean contains 1.5-2% caffeine, and the amount increases during roasting. Diuretic chlorogenic acid and trigonelline are degraded to a great extent during this process.


The typical coffee aroma consists of numerous aromatic substances; more than 800 compounds have been identified to date. Many of the compounds form during roasting via the Maillard reaction, among them bitter constituents. In addition to caffeine, other ingredients are also responsible for the bitter taste of coffee; caffeine accounts for only one third.


Because of its caffeine content, coffee has a stimulating effect. One cup (150 ml) of a normal-strength preparation of coffee contains 60-120 mg of caffeine, while a cup of espresso (40 ml) has about 45 mg. The caffeine effect occurs very quickly, in contrast to that of caffeine in tea. After only about 20 minutes the greater part of the active substance has been absorbed by the body. How long the effect continues differs with the individual, varying between 2 and 12 hours depending on how quickly the body breaks down the caffeine. This difference in the length of degradation is also the reason why some people can drink coffee even in the evening and still sleep afterwards, while others suffer from insomnia after enjoying coffee.


In addition to numerous vitamins and minerals, coffee beans also contain antioxidants. The carbohydrate content is 30-40%, that of fat and water each 10-13%, and acids amount to 4-5%. Protein is contained only in raw coffee, not in the roasted product.


One hundred milliliters of brewed coffee or espresso without milk and sugar contain:


Coffee, brewed, black

Espresso, brewed, without sugar

Energy (kcal)



Water (g)



Protein (g)



Fat (g)



Carbohydrates (g)



*n.a.: no data available


Harmful substances

Along with the stimulating effect of caffeine, in excessive amounts it can cause sleeplessness, nervousness and tachycardia (rapid heartbeat).


The coffee bean is protected by the pulp that surrounds it from harmful substances in the environment such as lead and cadmium.


The acids contained in coffee are not harmful to our health, but diseases of the stomach and gallbladder occasionally lead to acid intolerance. The precise mechanism is not yet clear. Whether in such a case the person is also unable to tolerate coffee must be examined on an individual basis.


Quality criteria, optimal storage conditions

The beans lose their aroma very quickly; when they are vacuum-packed they remain fresh somewhat longer. Once the package has been opened, the powder or beans should be stored in an air-tight container and kept in a cool, dark place. For optimal flavor the beans should always be freshly ground.


Presumed effect on health

Coffee was long considered to be addictive and dehydrating and to have negative effects on the development of circulatory diseases. More recent research results have repeatedly challenged these assertions.


It is meanwhile assumed that the consumption of coffee in moderation can actually have a positive effect on health. It is supposed to reduce the risk of developing type-2 diabetes, as well as senile dementia and Parkinson's. Moreover, it may reduce the risk of gallstones. Exactly which ingredients are responsible for these effects is still being studied. Researchers assume that substances that are formed when the beans are roasted work as antioxidants and are of decisive importance for the detoxification of the body. In diseases such as Alzheimer's, Parkinson's or type-2 diabetes the body requires additional antioxidants; a regular but not excessive intake of coffee could contribute to an adequate supply.


Form of consumption, use, processing, practical tips for preparation

The coffee bean is used predominantly to produce coffee powder. To this end, the greenish, raw coffee bean is roasted and takes on its - for us typical - brown colour. As already mentioned, numerous aromatic substances are formed during roasting.


After they are roasted the beans are sorted according to shape, colour and size. Unripe beans that did not turn brown during roasting, dried beans, beans that have been damaged by frost or are broken, and those that have fermented are eliminated: One such bean alone can affect the flavour of the coffee considerably.


After roasting and sorting, beans of different varieties are mixed together and sold ground to a powder or whole. Today, many ground coffees are no longer the product of a single variety but rather a mixture of many different ones.


The preparation of coffee differs according to region. In Germany and America chiefly filter coffee is drunk. The powder is measured into a paper filter and boiling water is poured over it. The Italians drink mainly espresso: Water is forced through the powder under high pressure. The oils contained in the coffee produce a foam, called crema. A plunger pot is popular in France: The water is poured directly over the coffee powder and the powder is pressed into the bottom of the pot with the help of a sieve. What remains is coffee with no coffee dregs whatsoever. And for Turkish coffee, or mocha, very finely ground coffee powder is mixed with a generous amount of sugar and water and brought to a boil three times, then poured into small cups. The powder may be drunk with the coffee or remains in the cup as dregs.


If you grind coffee yourself at home, you should note the following: Very finely ground powder is recommended for espresso and Turkish coffee, medium fine powder for filter coffee, and medium-coarse grounds for boiled coffee.


For quick preparation instant coffee was developed. A very strong concentrate is prepared from water and coffee powder and the water is then removed by one of two processes: freeze-drying or spray-drying with a hot gas.


Coffee is also used for various baked goods, desserts and sweets, as well as to make coffee liqueur.


More information about coffee can be found in the chapter on minimally processed foods.





  This article was written by




  With the website the Fritz Terfloth Foundation of Münster offers consumers independent and competent information about plant foods and their health effects. All texts are subject to German copyright law. Information about the conditions for use of the texts by third parties can be found here.