The color of coffee beans is a key indicator of their roast level, directly influencing your coffee’s flavor, aroma, and body. As coffee beans roast, they undergo a fascinating transformation, changing from green to shades of brown and even black. Each stage of this process unlocks unique flavor profiles, ranging from bright and acidic to bold and smoky.
The Agtron Scale is widely used in the coffee industry to ensure consistency and precision in roasting. This scientific tool measures roast levels based on the color of the beans, helping roasters achieve the perfect balance of flavor and aroma.
In this guide, we’ll explore the coffee bean color profile in detail, discuss the Agtron Scale, and provide a comprehensive table to help you understand the nuances of roast levels. Whether you’re a coffee enthusiast or a professional roaster, this guide will deepen your appreciation for the art and science of coffee roasting.
What is the Agtron Scale?
The Agtron Scale is a standardized system used to measure the roast level of coffee beans based on their color. It uses a spectrophotometer to analyze the light reflected from the surface of the beans, assigning a numerical value to the roast level:
- Higher Agtron Numbers: Represent lighter roasts (e.g., 80-100).
- Lower Agtron Numbers: Represent darker roasts (e.g., 25-45).
This scale ensures consistency in roasting and helps coffee professionals maintain quality control. Using the Agtron Scale, roasters can replicate specific roast profiles, ensuring that every batch of coffee delivers the same flavor experience.
Coffee Bean Color Profile and Roast Levels
Coffee beans change color as they roast, transitioning through distinct stages. Each stage corresponds to a specific roast level, which determines the coffee’s flavor, aroma, and body. Below is a detailed breakdown of the roast levels, their characteristics, and their corresponding Agtron numbers.
1. Green Coffee Beans
- Color: Pale green.
- Agtron Number: N/A (unroasted).
- Profile: Raw, vegetal, and not suitable for brewing.
- Flavor: None, as the beans have not undergone roasting.
- Use: Green beans are used for roasting and cannot be consumed in their raw state.
2. Light Roast
- Color: Light brown or tan.
- Agtron Number: 80-100.
- Profile: Retains the most original characteristics of the coffee bean.
- Flavor: Bright, acidic, and fruity with a lighter body. Often used for single-origin coffees to highlight unique flavors.
- Common Names: Cinnamon Roast, Half City Roast.
- Roasting Temperature: 356°F to 401°F (First crack occurs).
- Best For: Pour-over methods like Chemex or Hario V60.
3. Medium Roast
- Color: Medium brown.
- Agtron Number: 60-80.
- Profile: Balanced flavor with acidity, sweetness, and body.
- Flavor: Richer and more developed flavors than light roast, with caramel and nutty notes.
- Common Names: City Roast, Breakfast Roast.
- Roasting Temperature: 410°F to 428°F (Between first and second crack).
- Best For: Drip coffee makers, Aeropress, or siphon brewers.
4. Medium-Dark Roast
- Color: Darker brown with slight oil on the surface.
- Agtron Number: 50-60.
- Profile: Bolder flavors with reduced acidity and a heavier body.
- Flavor: Notes of chocolate, caramel, and spice with a slightly smoky undertone.
- Common Names: Full City Roast, After Dinner Roast.
- Roasting Temperature: 437°F to 446°F (Approaching second crack).
- Best For: Espresso or French press brewing.
5. Dark Roast
- Color: Dark brown to almost black with a shiny, oily surface.
- Agtron Number: 35-50.
- Profile: The roast profile overshadows the bean’s original flavors.
- Flavor: Bold, smoky, and bittersweet with low acidity. Often used for espresso blends.
- Common Names: French Roast, Italian Roast, Espresso Roast.
- Roasting Temperature: 464°F to 482°F (Second crack occurs).
- Best For: Espresso machines or Moka pots.
6. Very Dark Roast
- Color: Black with a very oily surface.
- Agtron Number: 25-35.
- Profile: Dominated by roast flavors, often with a burnt or charred taste.
- Flavor: Smoky, bitter, and heavy-bodied. Acidity is almost completely diminished.
- Common Names: Spanish Roast, Dark French Roast.
- Roasting Temperature: Above 482°F.
- Best For: Those who enjoy bold, intense coffee flavors.
Comprehensive Coffee Roast Table
| Roast Level | Color | Agtron Number | Flavor Profile | Common Names | Best Brewing Methods |
|---|---|---|---|---|---|
| Green Coffee Beans | Pale green | N/A | Raw, vegetal, not suitable for brewing | N/A | N/A |
| Light Roast | Light brown or tan | 80-100 | Bright, acidic, fruity, light body | Cinnamon Roast, Half City | Chemex, Hario V60 |
| Medium Roast | Medium brown | 60-80 | Balanced, caramel, nutty, moderate acidity | City Roast, Breakfast Roast | Drip coffee makers, Aeropress |
| Medium-Dark Roast | Darker brown, slight oil | 50-60 | Chocolate, caramel, spice, reduced acidity | Full City Roast | Espresso, French press |
| Dark Roast | Dark brown to black | 35-50 | Bold, smoky, bittersweet, low acidity | French Roast, Italian Roast | Espresso machines, Moka pots |
| Very Dark Roast | Black, oily surface | 25-35 | Smoky, bitter, heavy-bodied | Spanish Roast | Bold coffee lovers |
How the Agtron Scale Helps in Coffee Roasting
The Agtron Scale is a valuable tool for coffee roasters because it:
- Ensures Consistency: Roasters can replicate the same roast profile for every batch by assigning a numerical value to roast levels.
- Improves Quality Control: The scale helps identify under-roasted or over-roasted beans, ensuring only high-quality coffee is produced.
- Enhances Flavor Precision: Roasters can fine-tune the roast level to highlight specific flavor notes in the coffee beans.
For example:
- A roaster aiming for a bright, fruity coffee might target an Agtron number of 85 (light roast).
- For a bold, smoky espresso blend, they might aim for an Agtron number of 40 (dark roast).
Conclusion: Striving for Coffee Roasting Perfection
The color of coffee beans is more than just an aesthetic feature—it’s a window into your coffee’s flavor, aroma, and body. From the bright acidity of a light roast to the bold intensity of a dark roast, each roast level offers a unique experience. The Agtron Scale adds a layer of precision, ensuring every roast is consistent and accurate to its intended flavor profile.
At Daily Grind Roastery, we are committed to achieving coffee roasting perfection. By combining the art of roasting with the science of the Agtron Scale, we strive to bring out the best in every bean. Whether you prefer a light, fruity roast or a bold, smoky espresso, our expertly roasted coffee is crafted to deliver exceptional taste in every cup. Explore our freshly roasted coffee beans selection and experience the difference for yourself. Happy brewing!