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Coffee, from beans to shelf

Processing coffee beans is one of the most important activities in moderd business world.

From its origins over two thousand years ago, coffee bean processing has grown to a worldwide market whose output as a commodity has a dollar value second only to petroleum.

Though there are dozens of bean varieties, the plants fall into two main classes: the arabica, first cultivated on the Arabian Peninsula, and the robusta which contains about twice the caffeine.

By contrast to wine, the coffee berry (called a 'cherry') is not valued for its fruit, but only for the bean inside. It's that bean that is aged, roasted, ground and brewed to make the 400 million cups per day consumed around the world.

The beans come in two main varieties, green and red, with the latter - with its higher aromatic oil and lower acid content - used to produce the finer coffees. Hence one of the most important stages in the life cycle of bean to shelf is the picking.

Since most beans are hand picked by laborers, at the rate of a few baskets per day, separating the red and green is a valued skill and has a large effect on the final product.

After picking, the fruit is removed by soaking, scouring and mechanical rubbing. Then the beans are washed to remove any remaining flesh. This 'fermentation' stage produces beans which are then dried in the sun over large concrete or rock slabs, until they have about 12% water content.

From there the beans are sorted by color and size, sometimes by hand increasingly often by machine. Some of the beans are discarded, others polished to remove the skin. For select types, the beans are then aged anywhere from three to eight years, while others go to be roasted within a year.

During the 400-degree Fahrenheit roasting the beans expand to about twice their dry size, crack and change color from green to brown as oil in the interior is released. It's this oil that gives the different coffees their basic flavor.

Naturally a wide variety of in-house techniques have developed for roasting. Beans from Java and Kenya, for example, are often lightly roasted producing a distinctive flavor. After roasting, the beans produce carbon dioxide for several days so the beans are 'de-gassed' either by airing or packaging in semi-permeable shipping bags.

The resulting beans, up to a few weeks later, are then ground where again there are variations in styles and results. In some cases, 'burr' grinders are used to crush the beans to a consistent-sized granule. In others, choppers are used to chop the beans into small pieces with a less homogeneous-sized result. Turkish coffee is made by pounding the beans to a powdery consistency, using mortar and pestle.

The final result is then brewed, where the variety of styles and techniques is almost as great as the number of brewers. All these fine differences fall into one of four categories, however: boiling, pressure, gravity and steeping.

In 'boiling', hot water is run through the grounds then filtered or settled. In pressure methods, such as espresso, the slightly-less-than-boiling-hot water is forced through the grounds at high pressure. Gravity or 'drip brew' drips hot water onto coffee grounds and filters. Steeping is similar to the method of tea bags, though the bags are much larger.

Through its long journey from mountains or jungles, coffee beans go into making up one of the world's most treasured drinks. And with the new research demonstrating the health benefits of moderate consumption, one has even greater reason to be grateful for the effort. Cheers to coffee!