What's your assessment of this roast level?

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



Understanding the great degree of difficulty of interpreting color on computer screens and images (without Agtron specificity), it seems to me that a discussion of roast level, and which criteria we utilize primarily when determining (our interpretation of) roast level might be useful. So, here's a scenario to start the discussion...

Pictured above, Tanzania Pulp Natural Igamba Mpitu Peaberry, arrived at my house, 5/15. Color seems fairly accurate...

FCs = 7:30 @ 384 F (BT)
EOR = 10 @ 421F (BT). No hint of SC
Percent weight loss = 15.5%

Is this enough information to determine roast level? What is your interpretation of that level, and why? When there is conflicting data (Final BT vs BT rise after FCs vs color vs aroma vs weight loss) what is your most important determinant of roast level?

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Stereo Heathen
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#2: Post by Stereo Heathen »

Darker than I aim for. Based on your descriptions (pre-2c) I'd call it "full city".
I treat finish temperature and level of development as different aspects of a roast. However, given that I find a variety of finish temperatures palatable, but enjoy neither any green underdevelopment or flattened overdevelopment, I consider finish temperature the primary determinant in roast level.

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turtle
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#3: Post by turtle »

Am I the only one or do those beans look like they were blended post roast from two different roast levels?

How large of a roaster were these roasted in and how large was the roasting charge compared to the roasters max listed capacity?
Mick - Drinking in life one cup at a time
I'd rather be roasting coffee

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keno
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#4: Post by keno »

turtle wrote:Am I the only one or do those beans look like they were blended post roast from two different roast levels?
+1 That's a very uneven looking roast. I'd say it looks like FC+ and Vienna. Based on how dark some of it is I would imagine it tasting kind of ashy. This is what you see a lot with stovetop roasts.

Prescott CR
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#5: Post by Prescott CR »

Grind some up (espresso grind) and see what it looks like. There's more to the bean than the outside.

Having said that, 15.5% loss seems like a lot for a roast that didn't hit the second crack. I'd expect less than 15%.

It's really tricky to judge color via the internet. Having said that, going with that picture, that looks dark.

In order to judge color properly it's best to shoot with a camera that allows a RAW image and have a gray card in frame with the ground coffee and using a flash. After that there's the monitors that we're all looking at it with that have to be properly calibrated. Your photo doesn't have anything wrong, people just don't want to judge because of these variables.

I have the Antron tiles from a few years ago and don't really use them. I can send you the instructions for how to use them if you're interested- grind the coffee very fine and view it in a Petrie dish next to another with the color tile you're comparing it to both set in a black foam background in the same light. I mention this to show how difficult it is to really compare roast level in real life :)
-Richard

SAB (original poster)
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#6: Post by SAB (original poster) »

Thanks for the comments. My purpose of starting this thread was not to solicit a critique of my roasting techniques or picture taking ability, but more to open the discussion for what leads people to label a roast city, city+, and full city.

I will answer some of the inquiries. Roaster is HG/BM, 270 gms charge weight, well within the capacity of my roaster. The roast is a very even (for a dry processed coffee) one, and certainly the limitations of my photography are at play. There is no ashy taste, and I'm not concerned that somehow I missed second crack and over-roasted it.
Stereo Heathen wrote:Darker than I aim for. Based on your descriptions (pre-2c) I'd call it "full city"... I consider finish temperature the primary determinant in roast level.
This is exactly the kind of discussion I was looking for!

Do you ever consider weight loss, or is that just too variable? Do you consider finish temp as a set number (ie 420-425) or as an add on to some other landmark(ie FCs plus 30 degrees f). For me, FCs is a range, generally 385-395.

A compilation of different resources has implied that a city roast should have approximately 14-15.5% weight loss, end at 415-425F, and when I reach those milestones, I would consider the roast to be c+ or fc.
Prescott CR wrote: I mention this to show how difficult it is to really compare roast level in real life :)
Very true, if we're primarily using color as our guide. But if we use finish temp(either in absolute terms, or as a "FCs + x degrees to finish)we may be able to share a more reproducible vocabulary about roasts we are producing.

The more subjective our benchmarks, the less we can share with precision across the Internet. And we haven't even begun to discuss aroma in this whole equations!

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turtle
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#7: Post by turtle »

For me it is taste that identifies a roast. Color of the beans (once they leave the roaster) are not very important as long as the roast has developed at least past the grassy/lawn tasting cinnamon color.

I've roasted some Brazilian darker than what most people would to get a chocolate out of it but this is when I will blend with a lighter more fruity roast to give a good balance in the cup.

To me color is an indication of when to drop and little more.

A usually do not go lighter than this:



I have had SO beans come out different colors like this Ethiopian roast did:
'
Mick - Drinking in life one cup at a time
I'd rather be roasting coffee

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Stereo Heathen
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#8: Post by Stereo Heathen »

SAB wrote: Do you ever consider weight loss, or is that just too variable? Do you consider finish temp as a set number (ie 420-425) or as an add on to some other landmark(ie FCs plus 30 degrees f). For me, FCs is a range, generally 385-395.

A compilation of different resources has implied that a city roast should have approximately 14-15.5% weight loss, end at 415-425F, and when I reach those milestones, I would consider the roast to be c+ or fc.
I consider weight loss only when comparing roasts of the same coffee. Otherwise, within a fairly large range, comparing weight loss between two different coffees does nothing for me. On similar profiles and finish temperatures for different coffees I average around 13-15% weight loss, with specific palatable lows of 12.8% and highs of 15.6%. It's entirely dependent on the coffee. And when comparing numbers between different roasting machines and styles, I expect there would be even less correlation with roast level.

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Boldjava
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#9: Post by Boldjava »

turtle wrote:Am I the only one or do those beans look like they were blended post roast from two different roast levels?

...
Looks like a natural processed coffee which often presents varying finished color.
-----
LMWDP #339

Prescott CR
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#10: Post by Prescott CR »

When sharing roast profiles I suspect descriptors such as 'through the first crack' or 'just before SC' are probably the best way/s to describe a particular roast. That and your take on the flavor profile- bright & fruity vs chocolates vs dark chocolate/caramel vs roast-y.

I have some Tanzania PB Ruvuma 33/DE/04/151 GP (grainpro) which I do as a 'light' roast. For me that means into the FC a bit, my finish temps are ~425. I would say that it looks darker at that finished level vs central america coffees done for another 5-10 degrees until you grind them up.

For this particular coffee it seems like I am always trying to get it to develop without having the temps climb too much, perhaps because I typically do it in relatively small batches. Trying to avoid that divot or flick at the end is rough at 1/4 capacity for me.

Also, to add to what has already been said about some natty coffees- I have had roasts in my cooling tray that looked like 12 different roasts combined! I did a 'guess how many different roasts' thing with a picture of one Ethiopia on my Facebook page a while back. People guessed 4 and more when it was just one!

My sales guy calls Tanzania a great alternative to $$ Kenya coffees. I believe he is right!
-Richard

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