Diedrich IR-5 Analysis by Chris Kornman
Conventionally, we typically roast naturals more gently than washed coffees, and we tried that with Hirut Shallo’s natural from Yirgacheffe and felt like it was missing something. After discussing at length with Doris, consulting on her sample roasting style and her first Diedrich attempt, as well as asking Isabella to chime in on any insights from Ikawa sample profiling, I decided to take a crack at roasting the coffee with a slightly different approach.
Coffees like this present a unique challenge for a few reasons – first, delicate floral flavors are amongst the easiest to wash out with minor roasting errors. Second, the coffee is very dense, and requires a bit of extra heat for best results. However – especially with natural process beans – that density falls off quickly later in roasting and can present challenges for hot and fast roasting styles due to the tendency to run away from the operator at or around first crack.
The strategy I decided to employ here was to charge hot with a high burner setting and no soak, and keep the pressure on as much as possible until color change. An overly-extended Maillard phase didn’t particularly produce exceptional results on our first roasting attempt, so I wanted to make sure the momentum slowed but didn’t fall off completely.
These two tactics were relatively easy to accomplish using a combination of burner and airflow settings. However, I started hearing a few early cracks about 10F below the usual start of first crack. With my airflow fully opened and burners at minimum, the bean temperature was still increasing by over 20F per minute by the time I’d reached full first crack. My only option to slow the coffee down and avoid a massive upturn in bean temperature was to fully shut down the burners and coast.
The Diedrich’s ceramic plates did a good job of keeping the drum warm despite the flow of unheated air through the machine. I was able to push development past our usual range and get some good caramelization on the beans at a very low rate of rise in late-stage first crack.
I can’t emphasize the importance of this enough – the coffee is a little prone to underdevelopment. Even though color change and first crack seem to start a bit early, you’ve really got to push your color just a little deeper to make sure those enzymatic flavors – the fruit and floral notes buried in the green coffee’s chemical composition – are properly expressed in the cup.
Doris & I couldn’t wait for the rest of the team... we cupped it directly out of the roaster. Peachy sweetness and aromatic coffee and orange blossom were immediately clear. We let the coffee rest a few days and handed it off to the rest of the team to brew.
This was a fun puzzle to figure out, and I’d strongly recommend treating this coffee a little more like a washed coffee in the roaster. Get through drying phase quickly, don’t stretch Maillard too much, and take it just a touch darker for best results.
