Coffee bean

Coffee beans

Roasted coffee beans
Region of origin	Horn of Africa[1] and South Arabia[2]

A coffee bean is a seed from the Coffea plant and the source for coffee. It is the pip inside the red or purple fruit. This fruit is often referred to as a coffee cherry, and like the cherry, it is a fruit with a pip. Even though the coffee beans are not technically beans, they are referred to as such because of their resemblance to true beans. The fruits most commonly contain two stones with their flat sides together. A small percentage of cherries contain a single seed, instead of the usual two, called a "peaberry". The peaberry occurs only between 10% and 15% of the time, and it is a fairly common (yet scientifically unproven) belief that they have more flavour than normal coffee beans.^[3] Like Brazil nuts (a seed) and white rice, coffee beans consist mostly of endosperm.^[4]

The two most economically important varieties of coffee plants are the

Significant dates

• According to legend, the coffee plant was discovered in
  goat herder named Kaldi around 850 AD, who observed increased physical activity in his goats after they consumed coffee beans.^[10]
• The coffee plant was first found in the mountains of
  Mokha, Yemen
  .
• First cultivation in India (Chikmagalur) – 1600
• First cultivation in Europe – 1616
• First cultivation in Java – 1699
• First cultivation in Caribbean (Cuba, Hispaniola, Jamaica, Puerto Rico) – 1715–1730
• First cultivation in South America – 1730
• First cultivation in Dutch East Indies – 1720
• Roasted beans first sold on retail market (Pittsburgh) – 1865
• Important spray-drying techniques developed in 1950s, which along with freeze drying are a method to create instant coffee

Distribution

Brazil produces about 45% of the world's total coffee exports. The United States imports more coffee than any other nation. As of 2015, Americans consumed approximately 400 million cups of coffee per day, making the United States the leading consumer of coffee in the world.^[11]

Coffee plants grow within a defined area between the tropics of Cancer and Capricorn, termed the bean belt or coffee belt.^{[12][13][14][15]}

Etymology

The

The coffee tree averages from 5–10 m (16–33 ft) in height. As the tree gets older, it produces less fruit and slowly loses any pest- and disease-resistance. The coffee beans come from the seeds which contained in fruits from trees and shrubs naturally grown in African forests. Humans produce coffee by roasting, grinding and brewing the green coffee beans.^[17]

Coffee plants are often grown in rows spaced apart depending on the desired density chosen by the farmer. Some farmers plant other trees, such as shade trees or other cash-crop trees, such as orange trees around them or plant the coffee on the sides of hills, because they need specific conditions to flourish. Ideally, Arabica coffee beans are grown at temperatures between 15 and 24 °C (59 and 75 °F) and Robusta between 24 and 30 °C (75 and 86 °F) and receive between 500 and 3,000 mm (20 and 118 in) of rainfall per year.^[18] More rain is needed at the beginning of the season when the fruit is developing and less later in the season as it ripens.

Two lesser known species grown for consumption are Coffea liberica and Coffea racemosa.^[19]

Processing

When the fruit is ripe, it is almost always handpicked, using either "selective picking", where only the ripe fruit is removed, or "strip-picking", where all of the fruit is removed from a limb all at once. Selective picking is often used to produce higher quality coffee because the cherries are picked at their ripest. Strip-picking is indiscriminate and will harvest unripe, ripe, and over-ripe fruit. To improve quality after strip-picking, the harvest must be sorted.

Two methods are primarily used to process coffee berries. The first, "wet" or "washed" process, has historically usually been carried out in Central America and areas of Africa. The flesh of the cherries is separated from the seeds and then the seeds are fermented – soaked in water for about two days. This softens the mucilage, which is a sticky pulp residue that is still attached to the seeds. Then this mucilage is washed off with water.

The "dry processing" method, cheaper and simpler, was historically used for lower-quality beans in Brazil and much of Africa, but now brings a premium when done well. Twigs and other foreign objects are separated from the berries and the fruit is then spread out in the sun on concrete, bricks or raised beds for 2–3 weeks, turned regularly for even drying.

In Asia a third type of processing exists, where the

The term "green coffee bean" refers to unroasted mature or immature coffee beans. These have been processed by wet or dry methods to remove the outer pulp and

Nonvolatile alkaloids

Caffeine (1,3,7-trimethylxanthine) is the alkaloid most present in green and roasted coffee beans. The content of caffeine is between 1.0% and 2.5% by weight of dry green coffee beans. The content of caffeine does not change during maturation of green coffee beans, but higher caffeine content is found in plants grown at higher altitudes.^[20][21] Lower concentrations of theophylline, theobromine, paraxanthine, liberine, and methylliberine can be found. The concentration of theophylline, an alkaloid noted for its presence in green tea, is reduced during the roasting process, usually about 15 minutes at 230 °C (446 °F), whereas the concentrations of most other alkaloids are not changed.^{[citation needed]} The solubility of caffeine in water increases with temperature and with the addition of chlorogenic acids, citric acid, or tartaric acid, all of which are present in green coffee beans. For example, 1 g (0.035 oz) of caffeine dissolves in 46 mL (1.6 US fl oz) of water at room temperature, and 5.5 mL (0.19 US fl oz) at 80 °C (176 °F).^[22] The xanthine alkaloids are odorless, but have a bitter taste in water, which is masked by organic acids present in green coffee.^{[citation needed]}

Volatile compounds of green coffee beans include short-chain fatty acids, aldehydes, and nitrogen-containing aromatic molecules, such as derivatives of pyrazines (green-herbaceous-earthy odor). Briefly, such volatile compounds are responsible for the less pleasing odor and taste of green coffee versus roasted coffee. Commercial success was realized by Starbucks in creating Green Bean Refreshers using a process that primarily isolates the caffeine from the green beans but does not actually use steeped liquid from the beans.^[41] Many consumers experiment with creating green bean "extract" by steeping green coffee beans in hot water. Often, the recommended times of steeping (20 minutes to 1 hour) extract too much caffeine to provide a pleasant taste. A steeping time of 12 minutes or under provides a more palatable liquid that can be used as a base for a drink containing more of the nutrients and less caffeine that using just isolated caffeine extract.^[42] The alkaline stock base that results can be paired with acidic or fruity extracts, with or without sweetener, to mask the vegetable-like taste of the extract.

When green coffee beans are roasted, other molecules with the typical pleasant aroma of coffee are generated, which are not present in fresh green coffee. During roasting, the major part of the unpleasant-tasting volatile compounds are neutralised. Unfortunately, other important molecules such as antioxidants and vitamins present in green coffee are destroyed. Volatile compounds with nauseating odor for humans have been identified, including