Roasting technology brings out the deliciousness and pleasing aroma by applying heat to raw coffee beans. It is said that 70% of the taste of coffee depends on the quality of beans, 20% depends on roasting technology, and the remaining 10% depends on extraction technology.

Therefore, it is the most important factor to select good beans for drawing out the deliciousness of coffee. The roaster cannot change the composition of the beans, and they use the beans they bought. However, roasting technology is important because it accounts for 20% of the factors related to taste. It would be best if you kept to this principle.

The following considerations are crucial to bring out the best taste and aroma of the beans at the time of roasting:

If these variables change, the taste and flavor will change significantly.'

When roasting coffee beans, it is first necessary to thoroughly remove the water contained in the beans. Therefore, at the beginning of roasting, take time to dry the beans at a low temperature. When the water runs out, the beans start to be harden, so from here a full-fledged "roasting" will start so it is necessary to strengthen the heat (“Coffee Science” by Associated Prof. of Shiga Univ. Yukihiro Tanbe)."

I'll be a little more specialized, but heat is used to dry the beans and melt the ingredients at the beginning of the roasting process. This stage is called an endothermic reaction. Up to this point, it is necessary to take time to dry the beans thoroughly. After the drying is complete, the color of the beans starts to change little by little. Around this time, an exothermic reaction occurs in which components of the raw bean are oxidized and decomposed.'

"In the exothermic reaction, the color of beans　changes to brown due to caramelization and Maillard reaction. The radical reaction plays a vital role in browning, and H₂O₂ is generated in the process, and the brown pigment derived from chlorogenic acid is automatically oxidized.  H₂O₂ production and caramelization by the above and  H₂O₂  production by the Maillard reaction proceed overlappingly

Near the end of roasting, the necessary decomposition should have already been completed, so there is no need to raise the temperature further. Instead, I think it is better to heat slowly to determine the end point. "

(Coffee Roasting Chemistry and Technology (Professor Toshiro Nakabayashi of Shizuoka University

My idea is to make use this professional skill at home, and to connect with others persons through roasting.'

"About 600 kinds of ingredients are mixed in raw coffee beans" (“The coffee science I'd like to know more” by Prof. Yukio Hirose of Kanazawa University), In addition to the above fact, as stated by Prof. Hirose, the composition ratio also depends on the coffee production area, farm, or harvested year. In other words, the names of the ingredients contained and their composition ratios in the raw beans in your hand are entirely unknown.

The complexity of roasting is followed by how the taste is a result of various chain reactions as described below:

"The components in the beans undergo various chain reactions when heated. If the heating temperature changes or the heating duration time differs, the reaction products will differ, and the subsequent chain reactions will also differ. Depending on what kind of chain reaction will be followed, the taste and flavor of roasted beans are different."(“Coffee Science” by Associated Prof. of Shiga Univ. Yukihiro Tanbe)

As mentioned above, it's hard just to reproduce the taste and flavor, it can be said that it is impossible to bring out the ideal preference and flavor by a random heating method. Therefore, our ancestors accumulated the roasting history, repeated tastings, and devised a roasting profile (a record of heating temperature changes) in search of a better taste while comparing with the taste of beans roasted in the past. Even today, when science developed, this process remains the same.

On the other hand, it is not easy for an individual to record a roasting profile at home. You have to focus your attention and adjust the temperature and heating time while observing the ever-changing color and luster of the beans' surface, the color and amount of rising smoke, and the change in odor, and decide when to stop roasting. If you are fascinated by writing down the temperature and time, you tend to overlook the changes in the beans, and on the contrary, trying to determine the condition of the beans slows down the recording hand.

My idea is to make anyone can do this easily and at the same time try to breathe new life into the roasting of coffee.