Roasting dark: 'S' curve vs constant declining RoR? - Page 3

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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Almico
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#21: Post by Almico »

drgary wrote:Did you take your steadily declining BT ROR roast into second crack and compare that with a roast into 2C with a rising BT ROR at the end?
My dark roasts coast a few seconds into 2C. It takes good timing and lots of roasts on the same roaster to get a coffee to get to that point without the RoR rising. RoR wants to rise as it approaches 2C...desperately. If not deliberately held down by adequate heat adjustments well in advance, RoR will jump. So yes, I have had many roasts that tip up towards and into 2C. If it does it a little bit, the coffee suffers, but not badly. If that continues it will get roasty and loose sweetness.

Milligan

#22: Post by Milligan » replying to Almico »

Have you ever had a roast go flat ror during 2nd crack? If so did you notice if the roast suffered? I know there are implications during 1st crack if the ror flatlines, but didn't know if that was applicable to 2nd.

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drgary
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#23: Post by drgary »

It's worth experimenting because Neal reports a preference in class attendee tastings for ROR accelerating into 2C and Alan reports otherwise. Both are pros. I'm not. If I take coffee into 2C I want some roasty flavor, which tastes peppery to me, but I don't want to overdo it. Also I like to brew those coffees cooler. As Alan writes it's hard to get steadily declining ROR into 2C, but I'll give that a try for comparison.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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Almico
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#24: Post by Almico »

I was fooling around with Artisan Designer to try and illustrate how roast phases can affect RoR.

Some parameters are adjustable, some are fixed. For example: temp at yellow and 1C are fixed. Time to yellow and 1C are variable.

In this scenario charge temp, total time, RoR max and drop temp are all kept constant. Time to yellow and to 1C are manipulated and the effect on RoR is the result. Drop temp set to 420*, which is 5* into 2C on my roaster.

First, a perfectly sloped declining RoR



Next, time to 1C is extended to prolong Maillard phase, the "S" curve begins:



Even more, the "S curve extended:



You can see how you would have to reduce heat prior to 1C to lengthen Maillard, but then add heat to reach drop temp at the same time.

This can be mitigated by extending time to dry, which inherently shortens Maillard again, but removes the need to add heat late in the roast. Heat is lower after the turn, but carried longer into Maillard to keep momentum going through 1C.



Here it is in a video showing how changing the length of roast phases affects the RoR.

This exercise is an illustration of how all the phases of a roast work together. Yes, the yellow phase is important as it sets up the whole roast.

From my experience adding heat rarely helps a coffee. YMMV. The last profile shows how you can hit the target temp of 420* in under 12 minutes without having to increase gas. The question comes down to whether you feel the extended time in Maillard is worth allowing RoR to rise.

For me, I like to extend Maillard in lighter roasts to add complexity and shorten it in darker roasts to preserve some sweetness and acidity. All of that is accomplished with a declining RoR.
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Milligan

#25: Post by Milligan »

Almico wrote: The question comes down to whether you feel the extended time in Maillard is worth allowing RoR to rise.

For me, I like to extend Maillard in lighter roasts to add complexity and shorten it in darker roasts to preserve some sweetness and acidity. All of that is accomplished with a declining RoR.
Great insight that aligns with Rao's thoughts on the subject. He has a brief section devoted to this topic in his book. A quick quote...
Scott Rao Coffee Roasting Best Practices pg66 wrote:Intentionally manipulating the Maillard phase will usually come at the expense of a smoothly declining ROR. A smoothly declining ROR has more verifiable benefits in the cup.

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luca
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#26: Post by luca »

I'm sitting on the sidelines, but enjoying this discussion, as I'm unlikely to have much to suggest or try on this since I don't roast dark.

What would be really nice as a reader tagging along would be if people could describe what characteristics they look for in dark roasts. In particular, the dark roasting will impact some sort of roast flavour on the cup, and the exact nature of that roast flavour is the heart of this discussion.

Personally, I can't stand that black pepper type aroma that you can get in darker roasts. I received an excellent slightly darker home roast from a friend that basically still had a lot of the aroma of the underlying green, but had a bit of toasted walnut/roast beef character to it (the roast beef is a weird one, but it's part of the nez du cafe kit and once you smell it, you kind of go "oh yeah, I get it). No astringency, low bitterness, some acidity, perhaps slightly muted.

TW made some interesting observations about Kenyan coffee - he said that the classic blackurrant note tends to appear more at darker roasts, so by going lighter and emphasising berries and stonefruit more, with very high acidity, light roasts may be sacrificing that classic Kenyan characteristic a bit. I've got a kenyan coffee at the moment that is roasted a little darker and it's a filter roast, but I'm not really very happy to use it for that.
LMWDP #034 | 2011: Q Exam, WBrC #3, Aus Cup Tasting #1 | Insta: @lucacoffeenotes

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Almico
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#27: Post by Almico »

luca wrote:What would be really nice as a reader tagging along would be if people could describe what characteristics they look for in dark roasts. In particular, the dark roasting will impact some sort of roast flavor on the cup, and the exact nature of that roast flavour is the heart of this discussion.
The interesting thing about being a roaster/retailer is that I not only get to source, sample, profile and refine a wide variety of coffees, but I also get to brew the fruits of my labor and hand it directly to customers and experience their immediate feedback. My main coffee bar is also located in a touristy town where there is a consistent flow of new people that are trying my coffee for the first time.

After 5 years one thing has remained constant...an almost 50/50 split between people that like lighter roasted coffee and those that prefer darker roasts. People that like light roasts are repelled by roasty flavors and people that like dark roasts are put off by any kind of fruitiness or acidity whatsoever. They want chocolatey, nutty and savory flavors and some even like the bitter kick.

I reach for a light roast 90% of the time, but I also enjoy the occasional darker cup.

Capuchin Monk

#28: Post by Capuchin Monk »

luca wrote: if people could describe what characteristics they look for in dark roasts.
Almico wrote:people that like dark roasts are put off by any kind of fruitiness or acidity whatsoever. They want chocolatey, nutty and savory flavors and some even like the bitter kick.
Almico beat me to it.
I reach for a light roast 90% of the time, but I also enjoy the occasional darker cup.
I'm the opposite. I do go for fruity / acidic coffee when consuming milk based drink. For me, espresso, after getting used to it in Italy, is a dark roast drink.

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luca
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#29: Post by luca »

Almico wrote:After 5 years one thing has remained constant...an almost 50/50 split between people that like lighter roasted coffee and those that prefer darker roasts. People that like light roasts are repelled by roasty flavors and people that like dark roasts are put off by any kind of fruitiness or acidity whatsoever. They want chocolatey, nutty and savory flavors and some even like the bitter kick.
This is something that I find fascinating. And let me preface this by saying that, as always, I totally accept that people have different preferences and my agenda is for people to be able to predictably buy, roast and brew what they want.

Do you tend to select green that inherently has the desired traits for each roast level, or do you offer everything in all roast levels?

One thing that I never quite understood is that some coffee roasters seem to offer all types of green at all roast levels. And I do see discussion online from home roasters talking about things like how they dark roast yirgacheffe to amp up the body and reduce acidity for espresso, which they then go on to describe as chocolatey and nutty. I don't understand why you would take something that is inherently high in acid, low in body and fruity/floral and try to roast it into chocolatey, nutty, low acid and high in body. Makes far more sense to me to just start off with green that is inherently more like that.
LMWDP #034 | 2011: Q Exam, WBrC #3, Aus Cup Tasting #1 | Insta: @lucacoffeenotes

Capuchin Monk

#30: Post by Capuchin Monk »

luca wrote:And I do see discussion online from home roasters talking about things like how they dark roast yirgacheffe to amp up the body and reduce acidity for espresso, which they then go on to describe as chocolatey and nutty. I don't understand why you would take something that is inherently high in acid, low in body and fruity/floral and try to roast it into chocolatey, nutty, low acid and high in body. Makes far more sense to me to just start off with green that is inherently more like that.
I thought espresso is always blended. I guess some people do single origin for espresso... :?: