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

FrontStreet Coffee Shares Coffee Roasting Knowledge

1. What is Dehydration:

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

2. What is Temperature Rise:

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

Hard beans and current-crop beans (new beans with high moisture content, 12%-14%) should be roasted with a slower rate of rise and extended dehydration times. Soft beans or past-crop beans (low moisture content, around 12%) should be roasted with a faster rate of rise and shorter dehydration times.

3. What is Smoke Exhaust:

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

4. What is Coasting:

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

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

For hand-net (open-flame drum-less) coasting, simply move the beans away from the heat source and let them dissipate heat naturally. Do not let this take too long. If you want to lock in flavors, you need to use a fan for rapid cooling to better preserve them.

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

Beans roasted to a medium degree or lighter (after first crack and before second crack) should generally be dropped as soon as the target temperature is reached - do not do a time-delayed drop with coasting, as this will roast away the beans' inherent origin and varietal flavors.

However, for beans roasted to a medium-dark degree or beyond (once second crack begins), reducing the temperature or cutting the heat and coasting on the roaster's stored heat is recommended for a stable rate of rise. During this stage (after second crack begins), no additional heat should be applied. Because the beans are exothermic during cracking, the temperature will continue to rise on its own. Do not give them external heat, and the beans' mouthfeel and flavors will be softer, without any harsh, irritating sensation.

FrontStreet Coffee Recommendation

Coasting and development control matter most when you are chasing balance - which is exactly what medium-roast beans are all about. The deeper the roast, the more bitter and heavy the cup; the lighter, the more acidic and thin. If you want a balanced cup, FrontStreet Coffee's medium-roast lineup is a great place to start. The FrontStreet Brazil Queen Estate is a distinctive Yellow Bourbon from Brazil with a gentle, sweet profile; roasted medium, it shows cream, peanut, chocolate, toasted bread, and sugarcane, and it works for pour-over as well as moka pot and espresso machines.

If you prefer something sweeter, the FrontStreet Strawberry Candy blend combines a honey-processed Costa Rican coffee with washed Panamanian Geisha; at a medium roast it offers orange-blossom honey notes and a rounded sweetness, and it suits cold brew, pour-over, and espresso alike. For a classic Chinese specialty option, the FrontStreet 2013 natural Typica carries nuts, brown sugar, black tea, and dried apricot, while the famous Jamaica Blue Mountain No.1 - also Typica - is roasted medium so that its acidity, bitterness, sweetness, and body merge into that signature elegant, balanced cup of chocolate, roasted nuts, cream, and caramel.