Analyzing Coffee Roasting Techniques: What Are Temperature Ramping and Coasting?

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What is Dehydration:

Generally refers to the roasting process below 170°C. Different roasting equipment requires different dehydration times, but it's typically best controlled between 5-8 minutes. The main factor is the moisture content of the coffee beans (fresh beans generally have higher moisture content, so dehydration time can be extended).

2. What is Temperature Rise:

Usually, the temperature rise speed during roasting is controlled between 7-14 degrees per minute. This is related to heat control. The optimal temperature rise speed is best controlled around 10 degrees per minute. Different bean moisture contents result in different temperature rise speeds. (This generally refers to the speed of temperature increase).

Hard beans and current season beans (new beans with high moisture content, 12%-14%) should have slower temperature rise speeds with extended dehydration times. Soft beans or aged beans (low moisture content around 12%) should have faster temperature rise speeds with shorter dehydration times.

3. What is Smoke Exhaust:

The smoke exhaust volume during roasting becomes noticeable around 180°C. Smoke volume increases at first crack and reaches maximum after second crack. (The darker the roast degree, the greater the smoke volume). At this time, the damper should be fully open to avoid and reduce smoke flavor adherence to the roasted beans.

4. What is Coasting:

This is something many roasting beginners ask about and want to understand. Actually, the coasting action is cooling down or turning off the heat, using the roaster's temperature to continue roasting the beans. Throughout the entire roasting process, beans are absorbing heat, only first crack and second crack are exothermic actions. During these two stages, it's best not to increase heat for roasting, otherwise the beans can easily develop a spicy/burning sensation.

Coasting emphasizes turning off the heat and using the roaster's residual heat along with the heat generated by the beans during the cracking period to continue slow roasting. (Residual heat roasting, similar to simmering rice). But there's one point to pay attention to:

For hand net coasting, just leave the heat source and let the beans dissipate heat naturally. Don't let it take too long. If you want to lock in flavors, you need to use a fan for rapid cooling to better preserve the flavors.

Coasting action is not suitable for all beans and all roast degrees. (For light roast beans, coasting is not particularly recommended).

Beans roasted to medium degree or before (after first crack and before second crack) should generally be dropped when the temperature is right - don't have a "time-delay" drop with coasting, as this will roast away the inherent origin and varietal flavors of the beans.

However, beans roasted to medium-dark degree or beyond (after second crack begins) are recommended to have temperature reduction or heat-off coasting using the roaster's temperature for stable temperature rise. During this stage (after second crack begins), there should be no additional heat application. Because beans are exothermic during the cracking stage, temperature will continue to rise. Don't give them external temperature, so the beans' mouthfeel and flavors will be softer without刺激性感觉.

Important Notice :

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