January 30, 2025
Today's coffee that we are going to approach is the 2024 crop of Guatemala Acatenango Cooperative Asunción Maribel washed. The goal of sharing this roasting approach is not to give any kind of prescription on how to roast this coffee, but rather to provide you with some ideas of how to approach similar coffees.
Arrival QC:
The Coffee:
This coffee is a washed coffee grown in the high mountains of Acatenango, Guatemala. The coffee comes from a cooperative of multiple farmers and includes a mix of Typica, Bourbon, Caturra and Catuai. Grown at extremely high elevations, the coffee is very dense.
The Roaster:
For this roast, we'll be using a Proaster 1.5 kilo drum roaster hooked up to natural gas. Batch size is 500g, approximately 40% of roaster capacity. I've used a small batch size on this roaster to get closer to mimicking the gas power that you might find on a larger production roaster. It must always be mentioned that each roaster is different. The type of probe, placement of probe, and batch size will all influence the way in which bean probe temperatures are registered in a roaster. With that said, don't read too much into the exact temperatures, but look more closely at the theory behind the approach, time spent in different development periods, and rate of rise to get a better idea of how to translate this profile over to your own machine.
The Goal:
In our sample roast of this coffee, we found notes of chocolate, bright citrus acidity, florals, heavy body and juicy mouthfeel. In my roast of this coffee, I am looking to accentuate the complex fruit notes, balance the acidity, and maintain the chocolatey character that is a classic feature of many washed Guatemalan coffees.
You can read about my approach to coffee profiling and roast phases in my previous blog post here.
The Approach:
In this roast, I started with a moderately high charge temp and restricted air flow. Because this coffee is so dense and has an adequate moisture of 12%, I don't need to be too careful with this coffee through drying. On the roaster I use, I typically do not go beyond a charge temperature of 420. Here is use a charge temperature of 410 degrees F. I kept the gas application at 66%, ensuring that the coffee progresses through drying with enough energy to develop complex acids during Maillard. This coffee can take a LOT of heat. I would recommend that roasters play around with batch size in order to free up more heat energy in their roaster. Keeping a moderately restricted airflow through Maillard will also help with heat efficiency in the roaster.
Leading into Maillard, I adjusted the gas to the maximum setting. The goal of this is to create the maximum chemical reactions during this phase where sugars and amino acids are breaking down and recomposing into complex volatile aroma and acid compounds. Frequently the trick here is to apply as much heat as possible without incurring any roast defects such as scorching or cratering. Because of the high density of this coffee, this isn't a concern as it would be with many other coffees.
In order to achieve the goals of this roast, I need to ensure that there is a sufficient amount of time spent in the caramelization phase. During this phase I will be developing the melanoids that bring body and mouthfeel to the coffee, while also caramelizing the sugars that will provide the sweetness to balance out the natural citrus acidity. The trade off here is that time spent in caramelization will also break down the complex acids built up in Maillard. At 330 degrees, I began to reduce my gas application moving from 100% to 88%, then down to 66% at 375 in preparation for first crack. Additionally, I increased air flow ahead of first crack. When the bean opens up, many gasses will be released from the bean into the roaster. I increase my air flow in order to move those gasses off the beans and improve clarity in the cup.
First crack occurs on my roaster with this machine at 386 degrees. The crack is fairly intense and easy to hear. After first crack, I continued to slowly reduce the gas. The coffee finished with 1:11 of post crack development. It is important to remember that development is happening throughout the caramelization phase of the roast, not just once the beans begin audibly cracking. In situations where caramelization is extended, the coffee may not need a lot of post crack development time in order to achieve the desired result.
The coffee ended with total roast time of 8:23. Roast weight loss was 13.6%.
The Cup:
Aroma - Orange, caramel, chocolate, nougat, red fruit, honey
Tasting Notes - Round phosphoric acidity with notes of orange. Notes of milk chocolate, starfruit, red currant, and raspberry. The body was silky with a juicy mouthfeel. Soft florals of orange blossom, honeysuckle, and bergemont. The finish was a lingering dark chocolate and raspberry.
Bringing It Home:
I roasted 4 batches of this coffee, playing around with the development time and gas application. My overall impression of this coffee is that it has a lot to offer, but a roaster will need high temperatures to really unlock it. With lots of available acidity and sugars, it will be important to ensure that both high heat and adequate time in caramelization are incorporated to bring balance. Many of my roasts with this coffee were overly acidic when I didn't slow the caramelization down enough. Although, a bit tricky because you can't cut the gas/heat entirely and let this coffee coast to a finish. It needs to be pushed through the end. I believe this coffee will also lend itself to a darker roast profile with strong dark chocolate and cocoa powder notes. Denser coffees tend to excel in darker roasts as they can handle higher amounts of heat before developing carbon qualities. At very light roasts, this coffee can be overwhelmingly acidic and unbalanced. Shortening the caramelization phase on the lighter roast levels, you will find bright tangerine acidity, honey sweetness, notes of peach stonefruit, and a lemonade tartness.
While I believe this roast makes an excellent brewed cup, I would suggest extending the post crack development an additional 30-45 seconds for espresso. This will continue to reduce the acidity and increase the body of the coffee. Small amounts of bitter acids may begin to present with extended development, but they would not be noticeable in espresso preparation.
Happy roasting!
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