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TL;DR: Is there any science or data to support coffee that has undergone longer roast cycles needing less rest/degas time?

For some time, I have been doing my own roasting by cranking the machine to max temp, letting it rip, then stopping the roast when I am just short of my desired target and letting it coast to finish in the cool down cycle. For almost all varietals of beans, my target roast levels end up in the 14:30 to 16:00 minute range for a half pound of green coffee beans. Recently, however, I have been experimenting with significantly longer roasts (~30% to 50% longer). I set the machine to max (482F) let it run 12 minutes or so, then crank it down to 425F or so and run to just short of target. Generally this has been adding 4 to 8 minutes to my roasts times.

The obvious disadvantage is the extra time it takes me to be involved with the roast. The advantage I was going for was that it is much easier to hit a target roast with such a long window at the "end of roast". However, I seem to notice another potential advantage. The coffee seems to taste much better after much shorter rest times. With my old shorter method coffees came into their peak seemingly around 72 to 96 hours later. With this new method, the coffee seems to be hitting that same stride at 24 or 48 hours. This is anecdotally supported by the fact that the air tight jars I keep my beans in are noticeably less "poppy" when I open them to degas the day after roasting.

I can think of several reasons why this may be a thing, most just involving equations for the behaviors of gasses at various temperatures, but does anyone have a more solid reason why this might be? Or evidence that's it's all in my head (or taste buds) and just bunk?

  • I've heard that you shouldn't keep the roast temperature constant at the end for better flavor. However, I cannot remember the reason, nor its connection with degassing. Let me try to find the source. Then maybe we can resolve the mystery. – MTSan Aug 16 '16 at 19:37
  • RE: "poppy" sounds - Sweet Maria's recommends leaving the jar lids cracked for 8-12 hours after roasting to allow for degassing. I often leave fresh roasted coffee out in the open overnight. Oxidation is not really an issue with fresh roasted whole beans for the first few hours. – Mark Edington Sep 11 '16 at 1:51
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This relationship is often discussed on coffee websites that I visit, such as such as http://www.home-barista.com and http://www.greencoffeebuyingclub.com. I have had a similar experience, although my roast times are much shorter than yours (typically 11-12 minutes total).

I roast 3-4 coffees each week. Based on my own taste buds, coffees that are roasted closer to second crack are ready much sooner. I measure the length of time that I roast from the start of first crack. Here are some of the timing / aging notes for my recent roasts

  • Gedeo Worka 2014 - roasted to 1:45 after 1st crack, ready for drinking after 4 days
  • Yirga Cheffe Beriti 2014 - roasted to 2:15 after 1st crack, ready for drinking after 4 days
  • Rwanda Abakundakawa 2014 - roasted to 2:15 after 1st crack, ready for drinking after 4 days
  • Sumatra Gayo Mountain 2014 Bener Meriah - roasted to 3:00 after 1st crack, ready for drinking after 3 days

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