Why roasters should avoid micromanaging the flame during roasting

Esther Gibbs
May 10, 2023
An image of a large scale coffee roaster roasting coffee beans in an article on why roasters should avoid micromanaging the flame during coffee roasting

Several articles available online state the “do’s and don’t” of roasting coffee, which can make it difficult to know which school of advice to follow. For instance, some coffee trainers may focus on an ever-declining rate of rise (RoR), which may lead to you having to execute a series of small adjustments on the flame of the roasting equipment in order to ensure there are no plateaus or spikes. This is often referred to as micromanaging the flame during a roast.

However, many have begun to question whether this is the best way to manage a roaster. This is because a roaster has numerous variables that can be used to manage the transferral of heat. More so, a simple and repeatable roast profile should be used in order to produce consistent results. Notably, micro-adjusting the flame during a roast can make this process challenging. 

To gain insight into roasting variables and the discourse surrounding the micromanagement of the flame, I spoke with Q grader and the owner of Raf & Co, Raf Mlodzianowski.

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Your set-up is essential

Common controls on a roaster are flame power and airflow, with other models also providing control over drum speed. However, there are many more variables that give you optimum control over the roasting process.

“First, I would say the correct setup is the most underrated factor,” explains Raf, who is also AST in roasting, sensory, barista, brewing, and green coffee. “It is essential to have a chimney that provides good airflow, as this is often one of the most common issues contributing to a bad roast.” Setting up a roaster with a chimney that has minimal angles, allowing the easiest passage for the exhaust to flow outwards, can lead to cleaner roasts with a better transfer of heat. 

The next step is to work with the airflow, power, and drum speed controls. Establishing a correct airflow in order to avoid unnecessary heat loss is crucial, as the price of gas and electricity continues to rise. More so, the roaster must be cleaned regularly to prevent the buildup of chaff and coffee oils, which may lead to smokey or polluted roasts.

Additionally, you must determine the optimal gas levels for the roast, as most will not require 100% power. This may generate too much momentum in the roast, which may cause the roaster to do a “nervous-roaster-reduction” profile many people seem to use. Raf also explains there is no need to reduce the gas each minute, and those who do may not be in full control of the roast. 

The third step is drum speed, which optimises heat energy transfer and should be used in the same way gas is used. “I’ve found using different drum speeds for various batch sizes is unhelpful, as it changes the roasting environment too much if we are working to a fixed drum speed,” Raf explains. “When making changes to a roast or profile, we should keep the number of variables that are changed at once to a minimum, in order to remain in control.

When creating a roast profile, you should consider all of the above, as it can help you to plan a simple and repeatable profile with relative ease. “Ensuring you have planned a good gas profile is essential, and there really is no need to make more than three changes.”

An image of a coffee roaster inspecting roast coffee beans during a coffee roast in an article on why roasters should avoid micromanaging the flame during coffee roasting

What happens when you micromanage the flame?

Notably, you should be mindful of where you want the roast to start, where you want it throughout the middle, and at the end. Then, you will be able to plan the gas accordingly in order to maintain the energy and create the desired reactions and flavour. For example, if you are struggling to maintain the energy needed towards the end of a roast, you may need more energy at the start. Therefore, you could benefit from increasing the charge temperature or radiant heat of the roaster, or you may have lowered the gas too early. 

If you find yourself micromanaging the flame at the end of the roast, and continuing to bring the gas down in small increments because you are struggling to reduce the RoR, you may be flying towards your end temperature too quickly. To prevent this, you may want to start with a lower charge temperature and make larger incremental adjustments to reduce the gas at two or three points within the roast. This way, regain control at the end of your roast. Additionally, managing other variables, such as airflow, provides you with more stability. 

So, what actually happens when you micromanage the flame, and are there any risks? Raf was honest in his answer. “Nothing happens. Essentially, you are just wasting your time in doing so. It may look good to have such a complicated profile, but I often see it as a lack of understanding. For instance, if you change the flame 10% every minute, you could essentially just make one larger change because the thermal mass of the coffee doesn’t fall so fast,” He adds. “Just look how much cooling we need to bring the temperature down to a level we can touch.”

He believes an overdependence on probes and their flawed readings is what leads to roasters micromanaging the flame. “Remember, we are roasting the coffee and not the probe.” The probe itself is a measurement of data given by the surface temperature of the coffee beans. However, different probes have varying levels of sensitivity and reactions and may give off inconsistent information depending on their contact with the beans inside the roaster. 

By micromanaging the flame, Raf suggests you may be focusing on making the profile look ‘nice’ rather than on the control of transferral of heat and energy and, ultimately, the flavour of the coffee. 

An image of a coffee roaster using pen and paper instead of roasting software to determine the optimal roast profile in an article on why roasters should avoid micromanaging the flame during coffee roasting

How should you react to changes in a coffee roast?

Instead of being slow to react to changes, Raf suggests you plan ahead. A change in gas power is unlikely to have the desired intention you expect, especially in a heavy cast iron roaster with good radiant heat. Therefore, it is better to plan in advance and have a target for the start, middle and end of the roast, in order to make it simple and repeatable. 

Raf also suggests you go back to the basics in order to improve your roasting skills and confidence. “Stop using the computer and start taking notes using pen and paper. Focus on colour change, cinnamon, and end time. Learning to focus on those elements and controlling the time between them will help sharpen your instincts and produce more accurate roast profiles.”

Essentially, micromanaging the flame of the roaster will often make your job harder than necessary. It is essential that you focus on understanding how the roaster works and maintaining heat rather than having “instagramable” curves. It is important to understand the basics of heat transfer and how other variables, such as airflow or drum speed, can help to manipulate the transfer of heat. More so, you must learn about the chemical changes that happen in each part of the roast, from the drying phase to the Maillard reaction, and development. Then you will be able to make informed decisions that allow you to achieve the desired profile and end flavour.

Raf suggests you take time to play around with each roast and if you can hit the same points of time, temperature, and stages by using fewer changes or adjustments each time. Last, remember, the main goal is for the coffee to taste good, regardless of the profile looking ‘perfect’. 

In addition to offering specialty roasters and coffee shop owners’ custom-printed coffee packaging made from 100% recyclable and sustainable materials, MTPak Coffee updates the Education Centre daily. The free resource provides those in the coffee industry with a wealth of information about sourcing high quality green coffee, roasting tips, as well as the latest in roasting and packaging trends.

For more information on custom-printed sustainable coffee packaging, contact our team.

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