Coffee bean roasts vary on the type of coffee they are meat to end up as. Espresso roasts take longer to get out more of the sweetness within the beans and allow it to withstand the intensity of an espresso brew. On average, roasting takes 10 to 15 minutes. Before this occurs, the coffee cherries are picked and cleaned of their skin and pulp through a drying process.
At the beginning of a roast, it may smell like straw. Those conducting this procedure need to have their senses attuned to the roast. It is the only way to master this art without the help of advanced technology like sensors. During a roast, the chaff is left behind. It is the endocarp of the fruit, a parchment-like layer that directly sits on the beans. With heating, it is shed off like husks of nuts.
The chaff is collected and made into composts because they contain a lot of nitrogen and the caffeine within them is pest-repellant. Another by-product used for coffee processing is the skin. With greater frequency, it is being used to make teas known as ‘cascara’.
During roasting, the beans begin to expand and soon become mottled and yellow. Over time they stop taking heat energy and the change they undergo becomes exothermic. It is at this point that the sugars and oils within the beans derive their characteristic flavors. The heat is adjusted now and caramelizing takes place due to the presence of natural sugars resulting in browning.
The roast will be smelling great now but it is not quite ready. Beans keep expanding and pressure builds and they begin making “cracking” sounds. It is called “the first crack” and signifies the need to reduce heat. During espresso roasts, the heat is soon taken back up but usually not allowed to reach the point of “second crack”.
When beans are roasted optimally, they are removed from the heat, and further roasting is prevented through the use of a cooling process.