What Do Coffee Bean Roast Levels Mean for Flavor?

Green coffee beans turn brown only through roasting, and how long they stay in the drum decides the roast level. The Specialty Coffee Association of America built a reference system of eight levels on Agtron color values, from light roast to Italian roast, and each level lines up with its own acidity, sweetness and bitterness profile.

Higher Agtron readings mean a lighter roast. Light roast drops during first crack and brings bright acidity, though careless development can leave a grassy taste. Cinnamon roast lands near the end of first crack with sucrose or honey sweetness. The guide also covers second crack, Nordic ultra-light and Japanese ultra-dark styles, and home roasting advice.

Green coffee beans transform into brown roasted beans entirely through the key process of roasting. As roasting time varies, the surface color of the beans changes accordingly, giving rise to different roast level classifications. The Specialty Coffee Association of America (SCAA) established a reference system of 8 levels based on Agtron color values, from light roast to Italian roast, with each stage corresponding to a unique flavor direction and drop time. This article will use a text-and-image format to analyze one by one the color value ranges of each roast level, the rhythm nodes of first crack and second crack, and the evolution logic of acidity, sweetness, and bitterness. It will also introduce two niche styles—Nordic ultra-light roast and Japanese ultra-dark roast—and share how Front Street Coffee simplifies classification in actual production to help consumers understand roast levels. Finally, practical suggestions for the five stages of roasting and home roasting are included.

Green coffee beans are originally blue-green in color and only turn brown after being heated during roasting. The longer the heating time, the darker the bean color becomes, and the differences in the hues displayed on the bean surface at different drop times are collectively referred to by Front Street Coffee as coffee roast levels.

The largest coffee industry organization in the world—the Specialty Coffee Association of America (SCAA)—once developed a standard color card for coffee bean roasting, dividing roast levels into eight grades. The higher the color value reading, the lighter the roast. From light to dark, they are as follows:

SCAA number 95, Agtron color value 95, corresponds to Light Roast. The drop point is roughly during the dense period of first crack, meaning the beans are poured out while they are still crackling. This type of coffee usually has bright acidity, but if the middle development time is not properly controlled, it can easily bring out a grassy, unripe taste.

SCAA number 85, Agtron color value 85, belongs to Cinnamon Roast. The drop time is around just before or after first crack ends, when the cracking sound has just stopped or only a few scattered pops remain. At this point, the flavor is dominated by acidity, accompanied by a sweet aroma, and the aftertaste presents a clean sweetness like sucrose or honey.

SCAA number 75, Agtron color value 75, is called Medium Roast. The drop time is approximately after first crack has completely ended. Coffee at this level has sweetness as its main axis, mixed with a small amount of fruit acidity, and the finish leans toward the burnt sweetness of caramel or roasted sweet potato. On Front Street's bean list, coffees from Ethiopian regions mostly fall within this color value range, with the aim of strengthening the coffee's own caramel flavor while preserving delicate floral notes.

SCAA number 65, Agtron color value 65, is called High Roast. The drop time is approximately during the 1 to 2 minute quiet period after first crack ends and before second crack begins. The flavor presents nutty and caramel tones, with a balanced mouthfeel, disappeared acidity, and an overall full and solid body.

SCAA number 55, Agtron color value 55, is called City Roast. The drop time is roughly when second crack just begins, that is, one or two faint cracks are heard after the quiet period. At this point, bitterness is more prominent, caramel aroma intensifies, and the main tone approaches unsweetened pure dark chocolate, rich and mellow.

SCAA number 45, Agtron color value 45, is called Full City Roast. The drop time is approximately before the dense period of second crack, before a continuous series of crackling sounds is heard. Coffee at this point already belongs to the dark roast category, with a burnt-bitter, fragrant, and intense taste. If the bean surface to bean core develops evenly, using a coarse grind with low water temperature can brew a syrupy, thick mouthfeel, and the sweet aftertaste following bitterness is also quite obvious.

SCAA number 35, Agtron color value 35, is called French Roast. The drop time is approximately during the dense period of second crack, when crackling is heard again, but the sound is duller than first crack. At this point, the bean surface has begun to exude oil, and the coffee is extremely intense.

SCAA number 25, Agtron color value 25, is called Italian Roast. The drop time is approximately at the end of second crack, after the dense sounds have passed. At this point, the beans are pitch-black and glossy, with oil having penetrated to the bean surface. This roast level is only suitable for espresso, or coffee that needs sugar and milk to be drinkable. Currently, aside from Southeast Asia, few places roast beans this dark.

In addition to these officially listed classifications, in recent years more and more enthusiasts have noticed some new concepts, such as "Nordic ultra-light roast" and "Japanese ultra-dark roast." What do they represent?

First, let's look at the so-called "Nordic light roast," also called Nordic roast. By controlling roasting time and heat, it allows more aromatic substances to remain within the bean, thereby highlighting the coffee's light and delicate character, with a color value of roughly 85 to 90. According to Front Street's understanding, this style first emerged in Norway, and is currently represented by Norway, Denmark, and Sweden. Compared with medium-dark roasts, Nordic light roast coffee, no matter how it is extracted, has a noticeably lighter coffee liquid color and higher acidity. However, because of the light roast level and short heating time, improper operation can easily lead to problems such as "underdeveloped" and "sour and astringent" flavors, so it remains a niche style within the industry.

Ultra-dark roast, on the other hand, is one of the representatives of Asian coffee styles, coming from Japan, where people "prefer heavier tastes," and it is much darker than the dark roasts encountered in daily life. Japanese dark roast beans have a large amount of oil on the surface, looking almost like "black charcoal," with a color value of about 25 to 30. When extracted with a flannel filter or pour-over, the blooming stage expands very well, and you can clearly see the coffee bed actively degassing, continuously releasing a thick roasted aroma. The brewed coffee is mainly bittersweet, with a strong and intense entry.

Front Street Coffee does not directly copy this classification table when labeling its own roast levels, because coffee with roast levels numbered 95 or 45 to 25 is rarely seen in daily life. To make it easier for everyone to understand, Front Street Coffee simplifies roasted beans into the major categories of light roast, medium-light roast, medium roast, medium-dark roast, and dark roast, making it easier for consumers to grasp the concept of coffee roasting.

Good roasting can bring out the personality of green beans to the fullest while minimizing defective flavors to the greatest extent. But bean surface color meeting the standard color card requirements does not mean the coffee will taste good. Whether the bean core is fully roasted is the key to determining flavor quality.

Roasting coffee beans is usually divided into five stages: drying, dehydration, first crack, second crack, and drop.

1. Drying: When green beans are heated, internal water vapor evaporates. At about 135°C, the beans turn from green to light, gradually becoming whitish.

2. Dehydration: With continued heating, the green beans turn from green to light yellow. When the temperature rises to about 160°C, they emit a grassy smell or the aroma of roasted grain. With continued heating, the beans turn light brown.

3. First crack: At about 190°C, after dehydration is complete, the beans expand from heat and the cell walls rupture, forming first crack. At this point, a series of thermal decomposition reactions occur within the beans, among which the caramelization reaction brings sweetness, dark brown color, and body. First crack lasts about one minute.

4. Second crack: With continued heating, second crack begins, and the reactions within the beans become more intense, releasing a large amount of heat. After second crack ends, the green beans have basically turned black, expanded to about 1.5 times their original volume, with oil on the surface, and weight reduced by 12% to 20%.

This is a medium-light roasted washed Ethiopian Gedeb Cooperative coffee bean dropped one and a half minutes after first crack.

5. Stopping roasting: At the latest, it generally ends about one minute after second crack ends, when the temperature reaches 230°C; at this point it is a darker French or Italian roast. If heating continues beyond 230°C, the coffee beans may spontaneously burn.

If coffee beans do not have enough time to roast fully and thoroughly during the dehydration stage when they turn from green to light yellow, from yellowing to before first crack, they are prone to underdeveloped flavors such as greenness and grassiness. Therefore, slow roasting over low or medium heat, combined with a suitable rotation speed to keep the beans constantly tumbling, is very important for even heating.

For flat beans of regular shape, Front Street Coffee recommends setting the drum rotation speed to 60 to 65 revolutions per minute during roasting, and not turning the heat up too high all at once, otherwise the bean surface may caramelize prematurely, resulting in an outside that is roasted while the inside is not. If roasting peaberry, the rotation speed should be appropriately slowed to avoid insufficient heating caused by tumbling too quickly.

If friends want to roast coffee at home themselves, Front Street Coffee recommends buying a rotary drum-style roasting tool to ensure that the coffee beans tumble evenly during direct-fire roasting.

The above content is compiled by CoffeeHunters, a coffee news website.