What is the relationship between the roasting depth of coffee and the type of coffee beans?

Moderately roasted coffee has a moderate taste, balanced acidity and bitterness, and is suitable for most people. Deep-roasted coffee has a strong taste and a slightly bitter taste, which is suitable for buyers who like a strong taste.

Supplement: Broadly speaking, there are two kinds of coffee beans in the world, Arabica beans and Robusta beans. The earliest Arabs ate coffee by chewing the whole fruit ( Coffee Cherry ) to extract its juice. They then mixed ground coffee beans with animal fat as an energy supplement for long-distance travel, and it was not until about 1,000 AD that green coffee beans were boiled in boiling water to make an aromatic drink. After another three centuries, Arabs began to roast and grind coffee beans, because the Koran forbids drinking, making Arabs consume a lot of coffee, so religion is actually a big factor to promote the widespread popularity of coffee in the Arab world Blue Mountain, Colombia coffee belongs to Arabica varieties, coffee trees can be roughly divided into five kinds, of which Arabica (Arabica) and Robusta (Robusta) are more common.

Arabica species accounts for more than 70% of the world's total production. This variety is generally planted on slopes above 900 meters above sea level and is mostly produced in tropical high altitude areas such as Central and South America, East Africa, Southeast Asia and Hawaii. Corresponding to its pleasant aroma and rich taste, the tree species requires more artificial care and requires higher stability of temperature and humidity in the climate, so the price is naturally more expensive. Arabica is divided into many varieties, including the ancient Bourbon, and other fine varieties such as Catuna, Catuai, and Typica, which are generally adopted by growing countries. Of course, they may be pure, hybrid, or mixed-that is, different varieties are planted in a single estate and then mixed together to increase the complexity of coffee flavor. There are some exceptions, however. Sumatra grows its own endemic Sumatra species, while ancient countries like Ethiopia grow their own unique and traditional varieties. Roscoff, which is more adaptable to the environment, tastes mediocre, bitter and, more importantly, contains 2 to 3 times as much caffeine as Arabica. Generally grown in the slope of 200~600 meters above sea level, the requirements for artificial care are very low, the price is low, and it is mostly used for canned and instant coffee. Arabica beans are generally medium or deep roast, so the roast reflects the essence of the coffee flavor of this variety,(also known as single beans, that is, only one variety is not mixed with other varieties of beans single roast). For example, mixed coffee beans are generally medium and deep roasted, or deep roasted, so that the aroma and bitterness of coffee can be reflected, and the typical one is: Italian coffee uses this roasting method.

Why do some coffee beans use medium roast and some coffee beans use deep roast? Of course, there is also a possibility, as you asked: some bean roasting technology is not up to standard, the color of coffee beans baked in the same furnace is uneven, some look very dark or even close to black, while some are still very light coffee! Technical and equipment issues