The process of roasting coffee

1 is the state of raw coffee beans

2. Coffee beans are heating up at the furnace temperature.

3 as the temperature rises, the free water in the coffee beans begins to evaporate, and the beans begin to change from green to yellow. at this stage, the beans still have an obvious smell of grass.

(4) the coffee beans were further dehydrated and gradually changed from light yellow to longan-like colors. at this stage, the free water in the coffee beans was further removed, and the coffee beans gradually expanded.

5 the internal cells of coffee beans expand, accumulate heat and absorb a lot of heat, preparing for the first burst in the next stage.

The surface of the coffee bean becomes wrinkled, accumulating the last strength in an explosion, releasing the accumulated heat in a burst, crackling, and releasing an attractive fragrance.

When the first explosion is over, the coffee beans release heat and are once again designed to absorb heat and move forward to the second explosion.

8 entered the second explosion, the crackling sound was sporadic.

9 entered the second explosion dense, the bean surface is bright, under the burst action, some beans surface appears obvious "crater"

In fact, the whole process of coffee roasting is a process in which beans are heated, dehydrated, and roasted using the principle of heat conduction. in this process, the dehydration stage belongs to physical changes, and the chemical composition of coffee does not change. but this stage can be said to be the key to determining the quality of a pot of beans, because it is the force accumulated in the dehydration stage that drives the chemical changes in the next stage. Mena reflected that the beans entered an explosion and changed the chemical composition inside the coffee beans to form a unique aroma and flavor (which chemicals were produced and what specific substances were produced under specific conditions. Mankind has not yet studied thoroughly). The intense force in the previous stage is not enough to promote the effective chemical projection of coffee beans, and too much will make the reaction too fast to make the change develop completely. A pot of good beans requires bakers to rely on years of baking experience to brew. A little carelessness may make a pot of beans missing something.

Recently, I was translating an article entitled "what it takes to be an espresso roaster" (what it takes to be an Italian coffee roaster), which really makes me feel that being a baker is not easy, requires knowledge, and requires years of baking experience.