Diedrich IR-5 Analysis by Chris Kornman
Armed with green coffee specs indicating a dense and slightly high moisture bean, I opted (much like Evan) to charge with a high temperature and hit the gas early. Taking a page from Doris’ Diedrich playbook, I set my starting airflow at 50% (rather than the more common closed air baffle during early roasting stage) and fully opened it just prior to color change (which was observed at a somewhat low temperature of 303F), giving the burners plenty of oxygen to work with and trapping as little steam and smoke in the drum as possible.
About half-way through the Maillard stage, I backed off the burners to idle at 30% power the coffee continued to roast on pace. Edging up to first crack, I kept a close eye on the color and Doris (who’d been roasting the coffee on our Ikawa in the other room) came over to watch the end of the roast. As we waited for first crack, which finally arrived a little later than expected and very quietly, Doris mentioned she’d observed a similar phenomenon moments earlier.
At this point, the coffee’s momentum really began to tail off, and I dropped it a few seconds before stalling, with about 80 seconds of total post crack development time and a ColorTrack reading of 53.4 (ground). When we took this coffee to the cupping table to taste blind, next to Doris’ efforts on the Ikawa, our first impression of its fragrance was that of toasted grains -- not a super promising start.
However, I really warmed up to the cup as I began tasting. Loads of honey and vanilla-like sweetness, whispers of florality, and a lovely delicate pear flavor won me over. Doris was a little less impressed (her preference was for the faster sample-roast style Ikawa profile) but agreed with me that the cup cooled well and despite a few differences in flavor notes, our scores ended up nearly identical with high marks especially for its clean finish.
If I were to take this coffee for another turn in the IR-5, I’d likely charge even hotter and keep the pressure on a little bit longer during late stage Maillard. With copious built-in sweetness and a clear need for plenty of heat, I’d focus my energy on developing complex acidity and bringing out some more of the floral and fruit notes with a slightly higher ROR after first crack. The coffee seems to really crave heat at nearly every roasting stage, so don’t be afraid to give it what it wants.
