Roasting dark: 'S' curve vs constant declining RoR? - Page 6

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
User avatar
mkane
Supporter ♡

#51: Post by mkane »

It may be easy for you to achieve a declining R0R but it sure as heck isn't for me. My batting avg. is about 500.

Milligan

#52: Post by Milligan »

Perhaps he meant "straight-forward" to mean, we have widely publicized guidelines to follow to get a good light/medium roast.

Trjelenc (original poster)

#53: Post by Trjelenc (original poster) replying to Milligan »

Yes, moreso this. There's so much VERY detailed discussion on those roasts. Less detailed info the further you go after first crack, less of those theory discussions of flavor impacts and energy modulation schemes, etc.

User avatar
drgary
Team HB

#54: Post by drgary »

To my reading, Alan's examples here imply an option of a fast start and a moderate finish. He writes, "I like to extend Maillard in lighter roasts to add complexity and shorten it in darker roasts to preserve some sweetness and acidity." Others have commented on the need to enter 1C at about 20°F BT ROR to proceed to 2C without stalling. That suggests tapering power during Maillard to a target BT ROR that would anticipate the desired ROR at 1C and beyond. (He describes that as a variable stage.) Again, I'll have to try it but could set up a crash and flick. I'll review earlier roast profiles to see what settings are needed to avoid that. For an S curve roast plan, you don't need to add heat but not attenuate it as much. This could be done by having a target ET and maintaining that. He also writes about the difficulty of avoiding increased ROR later in the roast and that his tasting of that result doesn't recommend it. I can see increasing fan speed at that point, but my roaster maintains enough heat that the fan needs to be pushed hard. (This is as much a note to myself as a comment for others.)
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

N3Roaster

#55: Post by N3Roaster »

At a certain point you kind of just have to do the work of roasting, tasting, reviewing the data, and iterating on an idea. Progressive roasting exercises are an incredibly powerful training tool for that, but it can be difficult to justify at home roasting scale (much of the equipment is completely impractical for it and it's something that works out to be cheaper the more of the same coffee you're getting so financially this is unappealing at less than half bag quantities).

Another challenge when it comes to considerations of rate shaping is that temperature measurements are not the same across different machines. You can almost always find equivalent temperatures to construct a function taking temperatures on one machine and getting the temperatures that you'd read on a different one, but unless that looks like y = x + c (constant offset) it's going to be possible to construct a roasting plan that looks like a declining rate when viewed through the lens of one machine and not on a different one. It's not uncommon to see larger differences among machines at hotter temperatures (people who do this work more than I do have reported that sometimes the constant offset case exists, but in my experience it's almost always some kind of non-linear curve), which makes rate based considerations considerably less useful (or at least obviously not universal). Time within ranges combined with a measured roast level are, I think, a more useful framing unless everybody is talking about roasts on the same machine, though it's hard to justify the expense of that for a home roaster (or even most small commercial roasters).
★ Helpful

User avatar
drgary
Team HB

#56: Post by drgary »

N3Roaster wrote:Time within ranges combined with a measured roast level are, I think, a more useful framing unless everybody is talking about roasts on the same machine, though it's hard to justify the expense of that for a home roaster (or even most small commercial roasters).
Neal, thank you for explaining this recommendation so well.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

User avatar
mkane
Supporter ♡

#57: Post by mkane »

I switch between 2mm & 3mm BT probes mainly because I have 2 spots on the front of the machine with probes in place. The 2mm is in a location I think is optimum, darn near right @ 7:00. The 3mm is not so good. To close to the centerline. Bean temps are wildly different between the two. I prefer the 2mm probe as I think it tells the truth.

I like to focus on ET and percentages in each stage when comparing someone else's profile.