General knowledge of coffee roasting introduction of coffee baking methods

Pay attention to the change in color and taste-the color of coffee beans will change from green to light brown as it continues to heat up, and then a slight reddish brown of oil will be produced, followed by a large amount of oil that is shiny dark brown. At this point, you can no longer bake, otherwise the coffee oil on the surface of the beans will dry and give off a lot of smoke and scorched smell.

To sum up, coffee roasting is a science. The age, density, hardness and moisture content of raw beans will affect the quality of roasted coffee. Even the relative humidity and temperature on the day of roasting can not be ignored.

For coffee beans that have just been roasted, it is best to leave them for 2-5 days. It will be easier to drink after a large amount of carbon dioxide is discharged. Hong Kong Coffee Club will choose aluminum foil bags with one-way breathable valves to preserve coffee beans, which can prevent air from entering and causing oxidation, and can also let carbon dioxide out. Make sure the coffee beans are fresh and in the best condition. Pay attention to the sound changes-the coffee beans will burst twice during the baking process. The sound of the first explosion was low, indicating that at first the starch began to turn into caramel, and the water evaporated with carbon dioxide. The second burst sound is more violent and sharp, this is the sound of coffee bean cell fiber fracture, at this time should immediately stop heating, and as soon as possible with cold air to lower the temperature of the bean. The time of the first explosion and the second explosion can be very different, so when baking different beans, it is necessary to find out the most suitable baking conditions for this bean to achieve the highest caramelization-caramelization is an important factor affecting the flavor of coffee. Because raw beans absorb a lot of heat when roasting, there is the first explosion (1st cracking). At this time, the sugar begins to be converted into carbon dioxide and water continues to evaporate. The aroma of coffee will gradually come out and form coffee oil. This pyrolysis reaction can last until the second explosion (2nd cracking), but when the second explosion is completed, the temperature of the beans should be lowered immediately and as soon as possible with cold air, so that the highest caramel raw beans can be obtained after baking at more than 200 degrees Celsius, the moisture begins to evaporate, the volume will expand, the weight will be reduced, the deeper the baking is, the more weight will be lost.

Another phenomenon is that during roasting, coffee beans release carbon dioxide, and the roasted cooked beans will continue to exhaust within 30 days, which helps coffee beans keep fresh. This is because when releasing carbon dioxide, oxygen molecules are not easy to invade and destroy the flavor of coffee, so coffee beans will not oxidize. If the coffee beans are oxidized, the flavor will quickly deteriorate, so the coffee brewed with fresh coffee beans has a good flavor.