The process and stage characteristics of coffee roasting which kind of beans are suitable for hand-brewed coffee

The flavor of coffee not only depends on the variety of coffee, roasting is also a decisive factor.

Basically, the roasting of coffee is a kind of high-temperature coking, which completely changes the substances inside the raw beans, produces new compounds, and recombines to form aroma and mellow flavor. This effect will only occur at high temperature. If only low temperature is used, it will not cause decomposition, and no matter how long it is roasted, coffee beans will not be cooked. First, the baking process most people think that baking is nothing, just use the fire to cook the raw beans. In fact, in the process of coffee processing, roasting is the most difficult step, it is a kind of science, but also an art, so in Europe and the United States, experienced roasters enjoy a highly respected status. Baking can be divided into the following three stages:

1. Drying

In the early stage of baking, the raw beans begin to absorb heat, and the water inside gradually evaporates. At this time, the color gradually changed from green to yellow or light brown, and the silver film began to fall off, you can smell a faint smell of grass. The main function of this stage is to remove moisture, which accounts for about half of the baking time, because water is a good heat transfer conductor and helps to bake the internal material of coffee beans. Therefore, although the aim is to remove water, the baker will make good use of the temperature of the water and properly control it so that it will not evaporate too quickly; in general, it is best to control the water to reach the boiling point and turn into steam in 10 minutes. At this time, the internal material is fully cooked, and the water begins to evaporate, rushing out of the outside of the coffee beans.

2. High temperature decomposition

Baked to about 160 degrees Celsius, the water inside the beans will evaporate into gas and begin to rush out of the outside of the coffee beans. At this time, the interior of the raw bean changed from endothermic to exothermic, resulting in the first burst sound. After the bursting sound, it turns to endothermic again, and the pressure inside the coffee bean is extremely high, up to 25 atmospheric pressure. Heat and pressure begin to deconstruct the original tissue to form new compounds that create the taste and taste of coffee; at about 190 degrees Celsius, the transition between endothermic and exothermic occurs again. Of course, the high temperature cracking continued to occur, and the coffee beans changed from brown to dark brown and gradually entered the stage of heavy baking.