Relationship Between Green Bean Density and Roasting

The density of green coffee beans has a very close relationship with roasting. It affects heat transfer during roasting, determines the roasting profile, and even influences the final flavor development of the coffee.

What is Bean Density?

Coffee bean density is defined as weight divided by volume, representing the compactness of the internal structure.

• High-density beans: Generally grow at high altitudes with cooler climates, grow slowly, and have a denser internal structure.
• Low-density beans: Usually from lower altitudes or warmer climates, mature quickly, and have a looser structure.

How Bean Density Affects Roasting:

Roasting Strategies for Beans with Different Densities

🔸 High-Density Beans (e.g., Ethiopian Natural, Costa Rica)

• Higher initial charge temperature to quickly build internal heat.
• Extend drying phase to ensure internal heat penetration.
• Careful Maillard phase management for optimal flavor complexity.
• Extend development after first crack to highlight sweetness and aroma.

🔸 Low-Density Beans (e.g., Brazil, some Robusta)

• Medium to low initial charge temperature to prevent external scorching and internal underdevelopment.
• Shorter overall roasting time to maintain acidity and aroma.
• Quick passage through the Maillard phase to avoid excessive bitterness or smokiness.

Practical Application: Measuring Bean Density

Simple Method for Density Measurement:

Density (g/mL) = Weight (g) ÷ Volume (mL)

Steps:

1. Fill a measuring container with green beans (use water or sand for greater accuracy in measuring volume).
2. Weigh the beans.
3. Divide the weight by the measured volume to obtain density.

Density Reference Values:

• High-density beans typically > 0.70 g/mL
• Low-density beans typically < 0.65 g/mL

Flavor Profiles Based on Density (Under Identical Roasting Conditions):

Understanding bean density and adjusting roasting techniques accordingly is crucial to consistently producing coffee with optimal flavor and character.