What parameters are essential when translating profiles between roasters?

Esther Gibbs
December 22, 2023
roast profiles, translating roast profiles, translating profiles between roasters, coffee roasters, Ritual Coffee Roasters, custom coffee bags, custom printed coffee bags

As a coffee roaster, perfecting a roast profile takes skill, patience, attention to detail, and several cupping sessions. Beyond this, several variables come into play when roasting coffee. These include drum speed, airflow, charge temperature, finish temperature, and the transfer of energy throughout the roast. 

Notably, many roasteries may have different machinery within their establishment. For instance, some may have a different brand of sample roaster compared to their production roaster. Beyond this, they could have roasters of various sizes as the business has grown.

Roasting the same coffee on a different machine can be a nightmare for some, as translating profiles from one roaster to another can be a challenge. 

I spoke to Joel Kemp, the head roaster at Ritual Coffee Roasters in Cheltenham, UK, to find out what to prioritise and focus on when looking at translating profiles. 

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Understanding the variables of coffee roasting

While it’s not ideal, there may come a time when coffee roasters need to replicate a profile on a different machine. However, creating the same roast profile on two different roasters can be difficult. 

Roasters use three types of energy transfer to create the chemical reactions that create flavours in the last cup: conduction, convection, and radiation. Each roaster uses these three transfers in various ways, resulting in the coffee being roasted differently.

For the last three years, Joel has been roasting across various companies full-time. Previously, he worked as the senior roaster at Rave Coffee, and as a freelance barista and coffee consultant before settling at Ritual Coffee. 

“To get a perfect match of flavour when roasting the same coffee on different machines, you must consider all the variables,” Joel explains. “Roasters heat the drum, directly or indirectly, in different ways. And fluid bed roasters don’t even have a drum at all. These different styles of roasting give you various profiles, which can make matching difficult.” 

Another issue Joel highlights is that the relative target numbers can differ across machines. For example, he says “first crack on a Giesen w30 is around 180°C (356°F). A Loring is around 200°C (392°F), and a Samiac is between 192°C (377°F) and 198°C (388°F).

“Even something as early as colour change can vary across roasters, happening between 130°C and 160°C (266°F and 320°F). End temperatures are also exceedingly different,” he adds.

Therefore, it is not a case of uploading a roast from the profile software and following it blindly. To match roast profiles across different machines, you need to have a thorough understanding of the roasting process and what is going on within your machine. Furthermore, you need to understand what is happening within the beans at each stage of the roast to understand how to get similar results.

roast profiles, translating roast profiles, translating profiles between roasters, coffee roasters, Ritual Coffee Roasters, custom coffee bags, custom printed coffee bags

Translating profiles between roasters

There are a few ways to do this. Joel believes it is best to start with colour matching. ‘While colour matching may be ideal, you’d have to do a blind study to find out whether a colour match is an accurate match from two different machines,” he says. 

“I don’t have a colour meter at the moment, so I have to fall back on taste and relative goal matching and work from there.”

Relying on colour when switching profiles between machines requires trust in your physical senses. Beyond this, it means pulling out samples until you reach a colour which closely matches a sample from the roast on the other machine. 

For this roast, it would be best to follow the time frame set out for the previous profile. Aim to get colour change and first crack in as close a time as possible, regardless of the temperatures presented on your machine. 

Then, after first crack, drop the roast when you match the colour. That said, you must ensure you get a similar decline in your rate of rise at the end to match internal development. You could then use a colour meter to identify how close you are to the original. You then have a reference point for end temperature and know if it needs to be higher or lower depending on the results.

From there, you would need to rely on your pallet and understanding of the different stages of the roasting process and reverse engineer the process. “The best way to test if the coffees match would be triangulation, although this is not always necessary in a production setting,” Joel adds. 

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The importance of triangulating coffees

Triangulation refers to testing the differences or similarities between two coffees. To do this, you need to have three cups for each triangle. Two cups would contain your old roast, and one would hold the new roast. All cups are then tasted blind to determine the odd one out. 

An easy option is to put a sticker on the bottom of the ‘odd’ cup. The more triangles you line up, the more accurate your results will be statistically. If you’re unable to taste the ‘odd’ cup consistently across the triangles, your profile is a good match and customers are unlikely to taste the difference. 

If, throughout the process, you’re able to pick the translated profile, there’s a high chance customers can too. Therefore, you will need to return to your roaster and adjust. 

Joel says that while it may be true that ‘customers might not notice’, it’s still ideal for you to ship the coffee you’re confident is as close to the original profile as possible. If you’re unhappy with the match, you need to taste and analyse the differences and make suitable adjustments. 

For instance, if the coffee tastes hollow, it might be that the air setting is too high on the second roaster. If the coffee tastes smoky, maybe your air setting is too low on the second roaster. 

However, if the coffee is more acidic, extend the roast time as it might be underdeveloped due to the difference in heat transfer throughout the roast. This will provide more time for development. 

If there is an ashy or smoky flavour, check if the beans have scorching marks. You may need a lower charge temperature due to the drum being too hot. However, if scorching is not present, consider reducing the overall roast time to reduce the development of the bitter compounds. 

Translating profiles between roasters is not an easy task and requires a thorough understanding of the science of roasting. Improving your sensory techniques through tasting and having good quality control measures in place can vastly improve your chances of a successful transfer between roasters.

Doing this can help you confidently depict accurate taste notes on your coffee bags. In turn, this helps to further educate your consumers on the intricate flavours of specialty coffees. Custom-printed coffee bags can go a long way in helping your customers understand more about the coffee they are drinking.

MTPak Coffee offers roasters and coffee shops a range of 100% recyclable coffee packaging options that can be custom-printed to your business specifications. Choose from renewable materials such as kraft paper, rice paper, or multilayer LDPE packaging with an environmentally friendly PLA lining.

We use innovative digital printing technology to ensure your custom-printed coffee packaging is a perfect representative of your brand. We offer a quick turnaround and shipping times, as well as low minimum order quantities (MOQs) to micro-roasters who are looking to remain agile while showcasing a commitment to sustainability.

Images courtesy of Ritual Coffee Roasters

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

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