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如何写biology essay Coffee And Its Global Applications

 

Coffee (Coffea arabica) dried seeds are extensively processed before they make one of the most important beverages in the western world. Currently the crop is cultivated in many parts of the world and contributes significantly to those countries’ economies. The crop has originated in Ethiopia according to historical, linguistic, botanical and archaeological data. There are many myth stories and historical accounts that support the Ethiopian C. arabica origin. The linguistic data and the origin of Linnaeus taxonomy are also converging to the Arabian Peninsula as the coffee origin. C. arabica have been extensively studied with the use of molecular DNA marker analysis, simple-sequence repeats, chloroplast and mitochondrial DNA. These studies have showed that C. arabica has a center of diversity and origin in Ethiopia. Also the studies have discovered the reduction of C. arabica genetic diversity as the crop disseminated from its origin, which is common in many domesticated crops. From Ethiopia C. arabica has spread to Yemen where coffee was grown on plantations. Due to Yemen’s geographical location and trading with other regions of the world the coffee has quickly spread. From Yemen the coffee spread to Turkey and Egypt. Later the coffee was introduced to Europe where it was a highly valuable beverage. The history of coffee can also be followed by looking at the history of coffeehouses that have been established in Istanbul, Cairo, London and Paris. Coffee for a long time has been a subject of controversy, but the coffee has established itself as a social beverage.

Introduction

C. arabica is a coffee species that is important for the international coffee trade and the crop belongs to the Rubiaceae family which includes all tropical plants that produce something that is similar to a coffee bean (Charrier and Berthaud, 1985). There is a wide variety of uses of the coffee plant; it can be used as a flavoring, in ice cream, candies and liqueurs. Coffee pulp can be used to feed cattle. Also coffee can be used as a stimulant and diuretic (Duke and DuCellier, 1993). The area of C. arabica cultivation ranges from humid tropics to temperate climates and from sea level to 2,500m altitude, so the temperatures average 11-26.5°C (Duke and DuCellier, 1993). The distribution in these climatic conditions will provide abundant rain and light for the plant growth. The top ten coffee producers as of 2005 were, Brazil (2,179,000 MT), Vietnam (990,000 MT), Indonesia (762,006 MT), Colombia (682,580 MT), Mexico (310,861 MT), India (275,000 MT), Ethiopia (260,000 MT), Guatemala (216,000 MT), Honduras (190,640 MT) and Uganda (186,000 MT) data obtained from UN FAO (2005). Coffee is often called “The American Drink” and the United States consume more than 70% of Latin America’s annual crop (Latin America accounts for 85% of the world’s total production) (Uribe 1954).

C. arabica is mostly self-pollinating, so the genetic makeup of the progeny is similar to that of the parents (Wikipedia). Mostly C. arabica is a tetraploid, but deviations from the normal chromosome number have been found in C. arabica: triploids, pentaploids, hexaploids and octoploids (Sybenga, 1960). At the beginning of the rainy season 20 coffee seeds are planted, but half is eliminated naturally, in Brazil the seedlings are first grown in the nurseries and then planted in the soil; also often coffee plants are intercropped with other food crops such as corn, beans, or rice during first years of cultivation (Duke and DuCellier, 1993).

Coffee plants produce great harvest for 30-40 years. When planting young trees the first harvest can be collected after 3-4 years, with optimal production after 6-8 years. After the flowering it takes 7-9 months for fruits to mature, collecting the ripe red fruits will give the highest quality (Duke and DuCellier, 1993).

C. arabica seed contain per 100g, 203 calories, 6.3% water, 11.7 g protein, 10.8 g fat, 68.2 g total carbohydrate, 22.9 g fiber, 3.0 g ash and 120 mg Ca. Also raw coffee contains 10% oil and wax which can be extracted with chemicals (Duke and DuCellier, 1993). The coffee stimulating ingredients come from the three compounds caffeine (1.5%), theobromine (trace amounts) and theophylline (trace amounts), which are all derivatives of purine (Willson 1999). The caffeine is the least desirable of these compounds and many stores offer decaffeinated coffee. The chemistry of coffee flavor and aroma is complex: purine derivatives, chlorogenic acids and polyphenols (Willson 1999).

Coffee is a great crop and the beverage is delightful, but the caffeine in it has negative impact on human health. So the coffee decaffeination process is carried out to remove caffeine from the beverage. In the recent report the scientists at the University of Hawaii have identified the master gene for caffeine production and succeeded in blocking its function using an antisense gene carried by a bacterium, so the first caffeine-free coffee plants will be planted (Willson 1999). According to Willson if they succeed the growing of coffee plants that do not produce caffeine will replace decaffeination process, which is chemical and can damage beans and spoil their flavor.

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