Roasting transforms green coffee into the aromatic coffee brown, either whole or already ground, Most roasting machines maintain a temperature of about 550 degrees Fahrenheit. The beans are kept moving throughout the entire process to keep them from burning and when they reach an internal temperature of about 400 degrees, they begin to turn brown and the oil that locked inside the beans begins to emerge. This process, called pyrolysis is at the heart of roasting. It is what produces the flavor and aroma of the coffee we drink. When the beans are removed from the roaster, they are immediately cooled either by air or water.
At every stage of its production, coffee is repeatedly tested for quality and taste. This process is referred to as 'cupping' and usually takes place in a room specifically designed to facilitate the process. First, the taster -- usually called the cupper -- carefully evaluates the beans for their overall visual quality. The beans are then roasted in a small laboratory roaster, immediately ground and infused in boiling water, the temperature of which is carefully controlled. The cupper "noses" the brew to experience its aroma, an integral step in the evaluation of the coffee's quality. After letting the coffee rest for several minutes, the cupper "breaks the crust" by pushing aside the grounds at the top of the cup. Again the coffee is nosed before the tasting begins.
To taste the coffee, the cupper "slurps" a spoonful with a quick inhalation. The objective is to spray the coffee evenly over the cupper's taste buds, and then "weigh" it before spitting it out. Samples from a variety of batches and different beans are tasted daily. Coffees are not only analyzed this way for their inherent characteristics and flaws, but also for the purpose of blending different beans or determining the proper roast. An expert cupper can taste hundreds of samples of coffee a day and still taste the subtle differences between them