This article originally published in The Sturbridge Times, December 2016
By Elvis Dyer, Owner/Roaster, Sturbridge Coffee Roasters
Coffee beans are the seeds of coffee tree that develop inside coffee berries. According to legend, coffee was discovered by a goat herder when he noticed his animals grew friskier when they ate the berries off a certain shrub. After trying some of the berries himself, he too found himself full of caffeinated energy.
Today, coffee is the second most traded commodity, grown in 53 different countries, encompassing much of Latin America, Africa and Asia. Generally grown at altitudes of 4,000 to 6,000 feet, the more popular and tasty Arabica coffee requires more tending than the hardier plants grown at lower altitudes – which create the robusto bean, a harsher and more acidic variety.
The coffee cherries evolve from green to yellow, then, at their peak of ripeness, to deep red, which is when they are harvested. One acre of trees will produce roughly 10,000 pounds of coffee cherries which once processed, will yield 2,000 pounds of beans. The fruit of the coffee tree takes seven to nine months to reach maturity. A single tree will yield about one and a half pounds of coffee beans per season and each tree will be picked 4-5 times during the growing season.
The ripe red coffee cherries have several layers. Within the tough outside layer, there is a fleshy pulp surrounding a layer of protective parchment and silver skin that encloses two round or oval seeds or “beans” that are flat on one side. Once the cherries have been harvested, the fruit is cured either via a “wet” or the “dry” process. In the wet process, the skin and pulp of the cherries are removed and the remaining pit is allowed to ferment in order to loosen the remaining bits of skin and pulp. Once this is accomplished, the pits are washed, drained and dried. After the pit has dried, it is moved to a hulling machine which removes the parchment skin from around the pit. In the dry-cure process, the cherries are spread out and left to dry in the sun, a process that takes up to two weeks. It is more labor intensive, as the berries must be raked and rotated several times a day. Once sun-dried, the pits are moved to the hulling machine.
Once the beans have been graded by quality, which includes the size and color of the bean, the uniformity of the batch and the number of imperfections, and sold, it’s on to the roasting process. The beans are gently rolled in a drum and heated to temperatures varying between 350-450 degrees. During the first five minutes, any moisture left in the bean evaporates and the green beans turn a yellowish color. A few minutes later the beans will “pop” and double in size and then begin to darken, while any oils in the bean will rises to the surface. As the beans roast, the starches in the beans break down into sugar, causing caramelization and bringing out the dark brown color. At the end of the 10-15 minute roasting process, the beans will “pop” again before being released into a cooling tray.
Roasting beans is an art and science. Each roaster uses their own temperatures, measurements and methodologies. The goal in coffee roasting is to enhance the qualities of the green coffee beans and to develop them to their fullest potential. Each bean has its own unique flavor profile that the roaster enhances during the process. For example, bringing out a citric flavor or enhancing the chocolate notes. Generally, roasters will bring the beans to roasting levels such as:
Light Roast: This roast is light brown in color with no oil on the surface of these beans because they are not roasted long enough for the oils to break through to the surface.
Medium Roast: This roast is medium brown in color with a stronger flavor and a non to light-oily surface.
Dark Roast: produces shiny black beans with an oily surface and a pronounced bitterness. The darker the roast, the less acidity will be found in the coffee beverage. Dark roast coffees run from slightly dark to charred.
The flavor of a coffee bean peaks within a few days and decreases rapidly when exposed to air, light and humidity. We recommend you purchase whole beans and fresh-grind as needed. Do not store coffee in the refrigerator or freezer as this may add moisture to the mix, diminishing the flavor. Instead, store in a cool, dry place in a container with a tight-closing lid.
When brewing, make sure your equipment is completely clean, as old coffee oils can impart a bitter flavor to a new brew.