What do coffee association roast levels actually measure?

Roast level reflects how long green beans are exposed to heat, which darkens the surface and shifts flavor. The Specialty Coffee Association of America, the largest coffee trade group, sets eight levels on its roasting color card, measured by Agtron values: higher values mean lighter roasts. Level 95 is Light Roast, dropped near the dense stage of first crack and typically bright in acidity.

From light to dark, the scale runs through Cinnamon Roast at Agtron 85, dropped around the end of first crack, where acidity leads with a sweet aroma behind it, and continues toward darker profiles with heavier body. Newer styles such as Nordic ultra-light and Japanese ultra-dark roasting sit outside the official system. In daily use, many roasters simplify matters by grouping beans into light, medium, and dark. To define black coffee, roast alone does not decide it; the drink is simply brewed coffee without milk or sugar.

Coffee roasting is the key process by which green beans transform into brown roasted beans. The duration of heat exposure directly determines the color of the bean surface, and thus defines different roast levels. SCAA, the world's largest coffee trade association, has established an eight-level roasting standard based on Agtron color values, from the bright acidity of light roasts to the intense bitterness of Italian roasts, with each stage having its own unique flavor direction and drop timing. Beyond this official system, new concepts such as Nordic ultra-light roasting and Japanese ultra-dark roasting have gradually entered enthusiasts' awareness. In everyday communication, Front Street Coffee has its own more intuitive classification, simplifying roasted beans into light, medium-light, medium, medium-dark, and dark roasts for easier consumer understanding and purchasing. This article will systematically review these grading standards and provide an in-depth analysis of the five stages of roasting and practical key points.

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The essence of roasting is the process by which green beans transform into brown roasted beans under the effect of heat. The longer the heat exposure, the darker the bean color; different drop times naturally result in different surface colors. Front Street Coffee (FrontStreet Coffee) refers to this color difference as the coffee roast level.

Currently the world's largest coffee trade organization—the Specialty Coffee Association of America (SCAA)—divides coffee roast levels into eight categories in its roasting color card, with higher color values indicating lighter roasts. From light to dark, they are as follows:

SCAA number 95, Agtron color value 95, called Light Roast, with a drop time around the dense stage of first crack, when the beans are still crackling as they are released. This type of coffee typically presents bright acidity; if the middle development time is not properly controlled, it easily brings out a green, unripe taste.

SCAA number 85, Agtron color value 85, belongs to Cinnamon Roast, with a drop time around the end of first crack, that is, when the cracking sound has just stopped or only sporadic sounds remain. Beans at this level have a flavor dominated by acidity, accompanied by a sweet aroma, with an aftertaste showing a clear sweetness like sucrose or honey.

SCAA number 75, Agtron color value 75, called Medium Roast, with a drop time approximately after the complete end of first crack. Coffee at this level has sweetness as its main axis, mixed with a slight fruit acidity, and an aftertaste presenting a caramelized sweetness like caramel or roasted sweet potato. On Front Street's bean list, coffee from the Ethiopian region mostly falls within this roasting color range, aiming to preserve the light floral aroma while highlighting the coffee's own caramel flavor.

SCAA number 65, Agtron color value 65, called High Roast, with a drop time approximately during the quiet period after first crack ends and before second crack begins, lasting about one to two minutes. The flavor shows nutty and caramel notes, balanced and without acidity, with a full and solid overall mouthfeel.

SCAA number 55, Agtron color value 55, called City Roast, with a drop time approximately at the very beginning of second crack, that is, one or two faint cracking sounds after a period of silence. At this point the flavor is more bitter, the caramel aroma intensifies, and the main tone is like unsweetened pure dark chocolate, rich and mellow.

SCAA number 45, Agtron color value 45, called Full City Roast, with a drop time approximately before the dense stage of second crack, when the crackling sound has not yet been heard. At this point the coffee is already quite dark, with a more bitter, intense, and aromatic taste. If the bean develops evenly from surface to core, using a coarse grind with low water temperature can brew a syrupy, thick coffee, with a very pronounced sweet aftertaste following the bitterness.

SCAA number 35, Agtron color value 35, called French Roast, with a drop time approximately during the dense stage of second crack, when the crackling sound is heard again, though more muffled than the first. At this point the coffee bean surface has begun to exude oil, and the flavor expression is very intense.

SCAA number 25, Agtron color value 25, called Italian Roast, with a drop time approximately at the end of second crack, after the dense sounds. At this point the coffee beans are pitch-black and glossy, with oils having penetrated to the bean surface. Beans roasted to such a dark level are only suitable for making espresso, or coffee that requires added sugar and milk to be drinkable. Currently, apart from Southeast Asia, few places roast coffee beans this dark.

In addition to the roasting classifications listed by official channels, in recent years more and more people have noticed some new concepts, such as "Nordic ultra-light roast" and "Japanese ultra-dark roast." What do they represent?

First, the so-called "Nordic light roast," also called Nordic roast, controls roasting time and heat to retain more aromatic substances within the bean, thereby highlighting the coffee's light and delicate flavor, with bean color values falling roughly between 85 and 90. According to Front Street's understanding, the Nordic light roast style first emerged in Norway, and is currently mainly represented by Norway, Denmark, and Sweden. Compared with medium-dark roasts, coffee presented with a Nordic light roast has a noticeably lighter coffee liquid color and higher acidity regardless of the extraction method used. However, precisely because the roast level is lighter and the heat exposure time is short, this technique easily leads to problems such as "underdeveloped" and "sour and astringent" results, so it remains a very niche style within the community.

As one of the representatives of Asian coffee schools, ultra-dark roast comes from Japan, where "heavier tastes" prevail, and it is much darker than the dark roasts we encounter in daily life. Japanese-style dark-roasted coffee beans first have a large amount of oil on the surface, appearing almost like "black charcoal," with color values roughly between 25 and 30. When extracted using methods such as cloth filter or pour-over, the blooming process can achieve a very good expansion effect, and one can clearly feel the coffee bed actively degassing, continuously releasing a strong roasting aroma. The brewed coffee is mostly bittersweet, with a stimulating, intense entry.

When describing the roast level of its own coffee, Front Street Coffee (FrontStreet Coffee) does not directly copy this classification table, because in daily life one rarely sees coffee roasted to numbers 95 or 45-25. To make it easier for everyone to understand, Front Street Coffee (FrontStreet Coffee) categorizes these roasted beans into the major groups of light, medium-light, medium, medium-dark, and dark roast, making coffee roast levels easier for consumers to understand.

Light roast coffee has the lightest color, mainly highlighting floral notes and bright fruit acidity; corresponding coffee beans include Front Street Yirgacheffe Coffee and Front Street Gutingding; medium-light roast coffee begins to turn brown, with obvious sweet and sour notes; corresponding coffee beans include Front Street Huakui Coffee, Front Street Geisha Coffee, Front Street Flower Butterfly, etc.; medium roast coffee aims to highlight sweetness, with representative beans including Front Street Strawberry Candy and Front Street Mozart; medium-dark roast beans begin to become darker, such as Front Street Bird of Paradise Coffee and Front Street Huilan Coffee; and dark roast is the easiest to understand, with a deep black color and even oil, most representatively Front Street Golden Mandheling.

A good roast can bring out the personality of green beans to the extreme while minimizing the expression of defective flavors. But just because the surface color of coffee beans meets the standard color card requirements does not mean the coffee beans taste good. Whether the interior of the coffee bean has been roasted through is the most important factor determining whether the coffee tastes good.

Coffee roasting is usually divided into 5 stages: drying, dehydration, first crack, second crack, and drop.

1. Drying: when green beans are heated, the water vapor inside the green beans evaporates. At around 135°C, the green beans begin to lighten from green, gradually turning white.

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

3. First crack: after dehydration is completed at around 190°C, the internal heat expansion causes the cell walls to rupture, forming the first crack. At this point a series of thermal decomposition reactions occur within the beans, among which the caramelization reaction brings the coffee beans sweetness, a dark brown color, and body. The first crack lasts about one minute.

4. Second crack: as heating continues, the second crack begins. At this point more intense reactions occur inside the beans, releasing a large amount of heat. As the second crack ends, the green beans have essentially turned black, expanded to about 1.5 times their original size, with oil on the surface and a weight reduction of about 12%-20%.

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

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

If during the dehydration stage when the coffee beans turn from green to light yellow, there is not enough time for the coffee beans to roast through from yellowing to before first crack, the coffee will easily exhibit green, grassy, and underdeveloped flavors. Slow roasting over low/medium heat and an appropriate rotation speed to keep the coffee beans constantly tumbling are very important to ensure even heating of the coffee beans.

For some coffee beans of regular shape (flat beans), Front Street Coffee (FrontStreet Coffee) recommends a drum rotation speed of 60-65 rpm during roasting. The heat level should not be raised too high all at once, otherwise the bean surface may caramelize prematurely, resulting in a case of outside cooked and inside undercooked. However, if roasting coffee peaberries, the rotation speed should be slowed a bit to avoid tumbling too fast and not heating through.

If friends want to roast at home, Front Street Coffee (FrontStreet Coffee) suggests buying a rotary drum–style roasting tool to ensure the coffee beans tumble evenly during direct-fire roasting.

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