Coffee bean roasting: from dark brown to rich color

Coffee bean roasting is the process of subjecting raw coffee beans to high temperature treatment to produce a special aroma and flavor. During the roasting process, the coffee beans will undergo a color change from dark brown to fragrant. This change process is not only a change in appearance, but also a major change in the internal chemical composition.

First, at the beginning of roasting, the coffee beans are dark brown. At this time, the coffee beans have not been fully heated to a high enough temperature, and the internal moisture content is high. As time goes by and the temperature gradually rises, the moisture begins to evaporate slowly, and some cracks begin to appear on the surface.

Next, in the medium roasting stage, the coffee beans gradually turn brown or medium dark brown. At this point, the balance between the best taste and flavor has been reached. Due to the reduction of internal moisture, substances such as malt acid and amino acids react at high temperatures to form new compounds, a rich and complex aroma is formed at this stage.

Finally, in the deep roasting stage, the coffee beans appear dark black. At this point, the moisture inside the coffee beans has almost completely evaporated, so the roaster needs to be very careful to control the temperature and time to avoid over-roasting and causing a bitter taste. At this stage, the acidity in the coffee beans is reduced a lot, and more bitterness and burnt aroma are produced.

In short, the color change from dark brown to rich during the roasting process of coffee beans is not only a change in appearance, but also a major change in the internal chemical composition. Different degrees of roasting will bring coffee with different flavors and taste characteristics. For those who like a strong taste or prefer a fresh and sweet flavor, you can refer to this color change when choosing a coffee that suits your taste.