How to Distinguish Different Coffee Roast Levels

With the rapid growth of the coffee market in Taiwan, there are now more coffee varieties than ever. Beyond the quality of the green beans themselves, the roasting method and degree greatly influence a coffee’s flavor. Below is a simple guide on how to identify and categorize various roast levels.

Major Stages of Coffee Roasting

1. Dehydration (脫水期)

Green coffee beans typically contain 10–12% moisture. As the temperature rises, the beans gradually release water, and gases begin to form inside.

2. Maillard Reaction and Caramelization (梅納反應期與焦糖化期)

·       Maillard Reaction Phase
During this phase, the beans transition from a bluish-green color to a light brown or yellowish-brown hue, emitting a toasty, bread-like aroma. The Maillard reaction occurs when reducing sugars react with amino acids or proteins at room temperature or under heat, producing complex compounds called melanoidins.

·       Caramelization Phase
This reaction occurs specifically in sugar-rich materials. When sugar is heated to its melting point, it becomes syrup-like, then progressively darkens from a light golden color to a deep brown, and can eventually turn black if overheated. During caramelization, various flavors such as sweetness, acidity, bitterness, fruity notes, buttery caramel, and nutty undertones can emerge. If heated too long, the flavor can become bitter, and the color darkens significantly.

3. Flavor Development (風味發展期)

At this stage, the beans darken further, leading to “cracking” sounds as internal carbon dioxide and moisture expand and force the beans to split. This moment is critical for flavor development. To gauge roast levels, the Specialty Coffee Association of America (SCAA) promotes using the Agtron scale (ranging from 0 to 100). A higher number indicates lower caramelization (lighter color), while a lower number indicates higher caramelization (darker color).

Eight Common Roast Levels

Below are eight typical roast categories, from lightest to darkest. Each level features a distinct color, flavor profile, and aroma.

1.     Light Roast

• Drop Point: Around the start of first crack.
• Appearance & Flavor: Pale cinnamon color, often grassy with insufficient aroma and body. Rarely used for tasting, mainly for experimental purposes.

2.     Cinnamon Roast (淺度烘焙)

• Drop Point: From the start of first crack until it becomes more frequent.
• Appearance & Flavor: Light brown, with strong acidity and mild aroma.

3.     Medium Roast (中度烘焙)

• Drop Point: Between the peak of first crack and its conclusion.
• Appearance & Flavor: Light chestnut color, a balanced cup with mild acidity, moderate bitterness, and a medium aroma. Retains much of the bean’s original character.

4.     High Roast (中度微深烘焙)

• Drop Point: End of first crack.
• Appearance & Flavor: Light reddish-brown hue, crisp flavor with layered complexity. Acidity and bitterness are well-balanced, with a slight sweetness in the finish.

5.     City Roast (中深度烘焙)

• Drop Point: Between first crack and second crack.
• Appearance & Flavor: Light brown color, bright flavor, balanced acidity and bitterness, showcasing a coffee’s unique qualities. Considered a standard roast level—very popular among coffee drinkers.

6.     Full City Roast (微深度烘焙 / 深烘焙)

• Drop Point: Beginning of second crack.
• Appearance & Flavor: Brown color with a fuller body. Bitterness increases compared to acidity, but there’s a lingering sweetness and a robust aroma.

7.     French Roast (極深烘焙)

• Drop Point: From the intense popping of second crack to its end.
• Appearance & Flavor: Deep brown, nearing black. Strong, bold taste with prominent bitterness and almost no acidity. Intense chocolate and smoky aromas are common.

8.     Italian Roast (極深度烘焙)

• Drop Point: After second crack finishes, beans turn dark and oily.
• Appearance & Flavor: Very dark, glossy surface, close to carbonization. Extremely bold and complex flavor, dominated by strong bitterness and pronounced roastiness. Often used for Espresso.

By recognizing these roast levels and the accompanying aroma, flavor, and color characteristics, you can better appreciate how roasting influences your cup of coffee—and even guide your own roasting preferences if you decide to roast beans at home.