Let‘t Rock,Let’s Roast!
How to Roast Coffee Beans
Good coffee, in addition to having good raw beans, for its custom a matching roasting curve plays a 90% decisive role.
Coffee roasting curve is a graph describing the relationship between temperature change and time in the roasting process of coffee beans, reflecting a series of changes such as heat absorption, water evaporation and chemical reaction in the whole roasting process of coffee beans from raw beans to cooked beans. Here is a basic coffee baked beans curve explained:
1. Preheating Phase (Initial Dry Phase/Charge Temperature) : This is the beginning of the baked beans, coffee beans are put into the roaster, the machine is preheated first, at this time the temperature of the beans gradually increased, but the color change is little. The main purpose of this stage is to dehydrate and evenly absorb heat on the surface of the beans, preparing them for subsequent baking.
2.Drying Stage: when the temperature continues to rise, the water inside the coffee beans begins to evaporate rapidly, the color of the beans from green to yellow, the volume expands, and the silver skin falls off the bean table. This phase lasts about 5-8 minutes, and the temperature needs to be controlled to prevent the beans from burning.
3. The First Crack stage (First Crack) : with the further reduction of water, the sugar and starch in the bean begin to react chemically, producing a large amount of carbon dioxide and other gases, when the pressure reaches a certain degree, the bean will suddenly burst and make a similar sound, which is the so-called "explosion". This is an important turning point in the roasting, marking the initial ripeness of the beans and the acidity of the taste.
4. Development Stage: After the explosion, the baker will determine the length of development time according to the desired flavor characteristics, that is, the time from the explosion to the stop baking. At this stage, the color of the beans will change from light brown to dark brown, the oil will gradually precipitate, and the aroma will gradually form. The longer the development time, the acidity is reduced, the bitterness and mellow are enhanced, and the flavor tends to be rich and complex.
5. Second Crack stage (optional) : For deeply roasted coffee, it will also go through the second crack stage, which is the internal structure of the coffee bean further decomposition, resulting in a second round of cracking sound. Coffee beans that have undergone a secondary explosion will have a more intense caramelization reaction, showing darker color, lower acidity, and higher bitter sweetness, such as French or Italian roasting.
6. Cooling Stage: after the end of baking, cooling treatment is carried out immediately to avoid excessive baking caused by continued heating of beans. The cooling speed will affect the flavor stability of coffee beans.
Different roasting methods and their characteristics:
1. Light roast: Roasting time is 8-10 minutes, the coffee beans are a bright yellow color, with a small sheen on the surface, and the taste and aroma are maintained well, but the caffeine content is higher.
2. Medium roast: Roasting time is 10-12 minutes, the coffee beans are a dark brown color, with a sheen on the surface, the taste is round and the aroma is rich.
3. City roast: Roasting time is 12-14 minutes, the coffee beans are a dark red or black color, with a noticeable sheen on the surface, the aroma is intense, and the taste is slightly bitter.
4. Italian roast: Roasted at high temperature for 15-20 minutes, the color is a deep brown, the acidity and sweetness are reduced, but the aroma is rich.
