What determines the degree of roasting of coffee beans?

Coffee is that every coffee roaster has a different understanding of coffee beans and chooses a different degree of roasting. There may be no absolute right or wrong, but it is just a choice of flavor expression. It is not a universal standard. The second point is that the degree of roasting is not in a strict standard.

Under normal circumstances, the roasting degree is named after the color of the coffee beans, which is a standard color palette. The names of cinnamon, urban, Viennese, French, and deep French that we often use in textbooks come from this. This standard is only the general name of the international name, and there are often some exceptions in actual roasting, and such exceptions are not uncommon. For example, beans in some production areas are not easy to color, and further roasting will produce burnt bitterness, and the roasting has to stop here. Although the color is very light, its flavor has already formed. In other regions, the body may appear darker due to higher caramel content after roasting. In these cases, the color value is only a guideline.

Some people will use the oven temperature as the standard for the degree of roasting, but in fact, there are some differences between coffee roaster machines of different brands or technical routes, and the comparison of oven temperature between different coffee roaster machines is also very different, which is why we often In Japan, the roasting curve appears to be 230-240 degrees.


Roasting is to transform the chemical and physical properties of green coffee beans into roasted coffee products. It takes ten to fifteen minutes and the temperature is as high as more than 200 degrees Celsius. The popping sound and loss of moisture cause the green beans to swell and change their color, taste, smell, and density. With the roasting process, the chloric acid will gradually disappear, releasing familiar and pleasant fruit acids, such as acetic acid, citric acid, and malic acid contained in wine, and roasting is just right to present these beautiful sour tastes moderately come out. Thus producing a special flavor of the coffee.

Theoretically speaking, after the first crack, you can choose a suitable time to release it. But in order to avoid risks, under normal circumstances, the beans will not come out immediately after bursting, and it needs to be developed for two or three degrees to make the aroma more full. That is to say, from two degrees Celsius after the first crack to a little after the second crack, a total of only 10 degrees Celsius, we will roughly simplify it into three styles of light roasting, medium roasting, and deep roasting. The difference is not big, sometimes there may be only a difference of two or three degrees, but the appearance is already very different, so we will combine color, shape, and taste to describe the degree of roasting of a coffee bean.

From a roasting point of view:

Light roasting means that the coffee beans have been through the middle of the first cracking to the end of the first cracking. In the early stage of the reaction between the enzyme and Mena, the organic acids of the coffee beans have not been completely cracked, so the sour taste will be more eye-catching, and the bitterness will be light to no feeling. It is very suitable for those who like sour taste. coffee friends.

Medium roast usually refers to the period from the end of the first crack to the second crack. At this time, the roasting process is caramelized and reacts more with Mena. Although it still has a sour aroma, it is obviously weaker than light roast. At this time, the sourness and bitterness are relatively neutral, so the sweetness is more prominent, and it is very smooth, with caramel and chocolate as the main rhymes. This type of roast tends to bring out the best characteristics of specialty coffee.

Deep roasting usually refers to the beans after the second cracking. The caramelization reaction is coming to an end, and the Menard reaction is dominant, producing resinous, spicy, and carbonized flavors.

So, how do we decide on these different degrees of roasting?

The first basis is history. In the past, consumers did not have high requirements for the flavor of coffee and paid more attention to its function. During that long period, the degree of roasting of coffee was surprisingly consistent—depth. Therefore, the styles formed in the large coffee-producing areas during these hundreds of years are mainly mellow, such as Mandheling, Brazil, Colombia, or Blue Mountain. In contrast, Blue Mountain is mellow and not bitter, perhaps this is also an important factor for coffee to become the king of coffee in the old era. This roasting has a far-reaching influence, and until today, some consumers will ask for sugar and milk when ordering coffee, which is the result of this.

Therefore, in the selection of roasting, coffee beans from these classic producing areas, we will keep going back to that era as much as possible to maintain the classic mellow taste.

Taking Mandheling as an example, Mandheling’s unique “heavy taste” makes it drink like a hearty drink and a feeling of galloping in the rivers and lakes. There are not a few men who like it, and now many female friends also like it. Indonesia is the largest archipelagic country in the world and is known as the country of a thousand islands. Indonesia’s high altitude, volcanic soil, and its climate characteristics are all excellent conditions for the growth of Arabica coffee trees. Sumatra is known as the island of spices. The coffee trees in the mountains are associated with wild animals, cloves, cardamom, and pepper; coupled with the unique three-stage drying method (wet planing method), Mandheling has a unique flavor: unique Herb flavor, woody agarwood, appropriate acidity, mellow but like the sweetness and bitterness of life, with a strong aftertaste.

To achieve the desired roasting degree, you need a good coffee roaster machine that can control the temperature, time, and airflow of the roasting process. A coffee roaster machine can be either manual or automatic, depending on your preference and skill level. A manual coffee roaster allows you to adjust the settings according to your own judgment, while an automatic coffee roaster follows a preset roasting curve that you can modify or create. A coffee roaster machine can also have different capacities, from a few grams to several kilograms, depending on how much coffee you want to roast at a time. A coffee roaster machine can also have different designs, such as drum, fluid bed, or hot air, which affect the heat transfer and the uniformity of the roast. A coffee roaster machine is an essential tool for any coffee lover who wants to enjoy the freshest and most flavorful coffee possible.

mandheling coffee beans
mandheling coffee beans

Mandheling coffee beans have larger particles and harder beans. If Mandheling coffee beans are light roasted or medium roasted, the taste may not be as mellow as everyone likes, and the acidity will be more prominent, and it is no longer the Mandheling coffee that everyone likes. Of course, if someone likes sour mandheling, they can also try medium roasting. After all, mandheling without mandheling, do we also call it mandheling?

The second basis is the shape and characteristics of beans. For example, Yirgacheffe coffee beans will choose light roasting. It is not that this region shows good acidity, but on the contrary, it is because of the extremely light roasting that leads to its acidity.

Yirgacheffe Ethiopia, in order to sell most of the coffee beans, coffee farmers do not like the traditional countries like Brazil, Mandheling, and Colombia that like to classify commodities by size. Ethiopian coffee will be There are large and small, only the defective beans that will bring bad taste are excluded, and for the phenomenon of different sizes, the original species [Heirloom original species] is usually used to indicate the raw bean variety.

Yirgacheffe coffee beans
Yirgacheffe coffee beans

The beans in Ethiopia come in different sizes. When roasting, the big coffee beans should be roasted thoroughly, and the small coffee beans should not be burnt. The safer way is to get them out of the oven as soon as possible. Some people say, isn’t it possible to roast evenly with high technology? The wooden structure of coffee beans determines that their heat conduction is very slow. If the difference between soybeans and adzuki beans is too large, this kind of heat conduction cannot be achieved evenly. Although it can be achieved by reducing the firepower after dehydration and slowly prolonging the roasting time, this method of boiling frogs in warm water can make the bean salad look uniform, but the aroma characteristics are inevitably bland and tasteless due to excessive roasting. This is also a trade-off.

For another example, Geisha is different from most varieties of coffee. Many commentators think that it is a medium-light roast because of its characteristic. One characteristic of the Geisha variety is that its narrow and long shape makes it larger than some varieties, especially the Ethiopian beans that have been unanimously recognized as light roasted. The size of two or three small grains can often catch up with one Geisha, regardless of Like it or not, it takes longer to roast. On the other hand, in terms of the principle of roasting, roasting as much as possible without causing burnt bitterness will produce more aromatic characteristics and lead to more flavor changes, which is the pursuit of roasting.

Whether it’s the roaster or the drinker, they have different understandings and views on coffee. Sometimes there may not be a completely standard answer, but a different choice.

Leave a Comment

Your email address will not be published. Required fields are marked *

+86 17836969360