I'm Kamei, owner of Gokujo Kabinashi Coffee.

When you've had coffee, have you ever felt an unpleasant harshness or sourness lingering on your tongue?

This might be because the coffee was "under-roasted." Even if the surface looks appealingly brown, if the beans aren't cooked through to the center, this unpleasant taste can occur.

Not only do such beans taste bad, but there's also a higher chance of mold developing in their core.

1. Preventing "Under-roasting": The initial "drying" stage of roasting

To prevent under-roasting and produce clean, delicious coffee, a crucial process called "drying" is performed during the initial preparatory stage of roasting.

Stage where drying takes place

Drying occurs after coffee beans are loaded into the roaster, the temperature of the drum temporarily drops, and then rises again until it reaches approximately 160°C.

Purpose of drying

During this stage, from low to medium temperature, heat is slowly and thoroughly transferred to the core of the beans. The primary purpose of drying is to evaporate or sublimate excess moisture and components that lead to unpleasant off-flavors that would otherwise interfere with the coffee's taste.

2. Why neglecting the drying process harms coffee flavor

If this drying process is not properly carried out, undesirable components will remain inside the beans.

• Unpleasant sourness/harshness: Residual moisture and components in the core undergo incomplete changes due to heat, causing unpleasant lingering "harshness" or "astringency" on the tongue.

• Inconsistent flavor: A large difference in moisture content between the inside and outside of the beans leads to uneven heat transfer during subsequent roasting, resulting in inconsistent flavor.

3. Gokujo Kabinashi Coffee's commitment to roasting

In our roasting process, we place great importance on this "drying" stage.

When we roast, we precisely assess the type of bean, characteristics of its origin, and the moisture content within the beans, performing optimal drying tailored to each bean. This meticulous preparation is the secret to delivering clear, pure, and delicious coffee to our customers.

Next time, we would like to take the opportunity to discuss the scientific mechanism of how heat is transferred to the core of the beans inside the roaster. Please look forward to it.