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How to Manage Rate of Rise

By Carson Parodi on

Photo courtesy of Sean Benesh/ Unsplash

By now it’s clear how critical it is to micro-manage your roast at almost every stage of the cycle. In the past weeks, we’ve discussed the development time ratio along with tips for both dark and light roast coffee. But perhaps the most crucial window into controlling those things is understanding and managing your rate of rise — doing so will prevent baking, charring and other less than desirable coffee characteristics.

Rate of Rise. Rate of rise (RoR) refers to the rate at which a coffee bean's internal temperature is increasing during a roast. It is often characterized on a roasting curve, which, coupled with bean temperature readings, gives you a pretty clear window into what’s happening to your beans as they roast.

While the coffee beans should indeed always be getting hotter throughout a roast, it has become increasingly accepted that the RoR is usually decreasing steadily. In other words, the beans are always getting hotter but are doing so at a slower rate.

High or Low RoR? There’s lots of chatter within the roasting community about high or low RoR. A high rate of rise means that your roast (bean temperature) is developing rather quickly, and a low RoR means your roast is developing slowly. Remember that different RoR’s can accentuate different characteristics like body, sweetness and acidity. You will find your personal sweetspot over time and with practice.

We generally avoid a slow RoR because doing so you can run the risk of stalling your roast and baking your beans.

RoR in Countertop Roasters. Obviously, countertop roasting units like those from FreshRoast and Behmor don’t allow for computer connectivity and roasting curve readouts, but some home hacks like to use a timer and a thermometer to calculate their own RoR on any given roast. It can be calculated by recording the change of your beans’ temperature over any given amount of time (typically around 30 seconds).

Steady...steady...steady. Regardless of method, your RoR needs to be steady, not erratic. We can’t stress this enough. A RoR that is jumping around wildly will often end in a baked roast. Try your best to keep things uniform by managing your heat application appropriately.

This is particularly important as you approach, enter, and move through three critical inflection points: Before first crack; immediately after first crack; and toward the end of and after first crack. Unpacking these deserve their own posts, so stay tuned. But for now, this is what we hope to impart:

  1. RoR is the slope of the rate your bean temperature is changing and is a highly sensitive variable. Watch it closely. Calculus students will recognize that it’s the derivative of the temp curve.
  2. After the temperature peaks near the beginning of a roast when bean temperature finally matches roast chamber temperature, it’s important to maintain a constantly and steadily decreasing RoR.
  3. Things get tricky as beans approach and run through first crack and you need to be watching and managing carefully. How you manage this phase will also also influence the possibility of the dreaded “flick” (temperature spike) toward the end of first crack.
  4. If you don’t have a roasting setup that provides a computerized read out, don’t fret. These are still very important characteristics in a roast sequence and you can learn to manage them by pure “art” if you’re tuned in to and can visualize what’s going on. As an example, even with the tech we use, visual inspection of the beans (more than a graphic readout) tells us when we are nearing first crack, so we go into high-alert mode.

Here is an example of a very good roast. Notice how the RoR is steady, and does not fluctuate dramatically at or around first crack. This kind of curve is not natural and only comes with experience. Or pure luck!

Courtesy of RoR roasting wizard, Scott Rao

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