IBTS Temperatures for Roast Levels

I am curious what temperatures people select for their target roast levels. Of course, I am expecting it to be a range as each coffee is different.

Specifically, I’m asking about City, City+, Full City, Full City+.

I’ve also noticed that there is a general disagreement for what each roast level means. I use the Sweet Maria’s guidelines, which is that City is the lightest roast that is drinkable, mottled in color, most likely in the middle of first cracks. City+ is in-between Full City and City, slightly mottled in color, more uniform, less chaff. Full City is before second cracks where the coffee is a uniform color, softer edges, slight oil sheen. And Full City+ is at the start of second cracks.

I use Sweet Maria’s guidelines for those definitions you mentioned but I haven’t been using temp targets because I find each bean density and their processing method seems to affect when you hear the cracks. That’s just my own observations - I didn’t try to do any in-depth data analysis to validate that observation. Coming from the FreshRoast SR500 I relied on the sound because the K temp probe isn’t too reliable of a setup with the SR500. Just my 2 cents.

FWIW I found an excel spreadsheet of temp targets that I saved but I neglected to note down the source. I’ll try to find it again to see if I can post it up here if there is interest. I don’t know exactly how those temps were determined but it was a good rough guide. LMK if interested

I’m also coming from a FreshRoast (SR800) and I find it more difficult to rely on sight and sound now. One thing that seems fairly common for me is that my first cracks seem to take much longer than they did on my FreshRoast, and that really throws off my senses. Besides, I think using the sensors are a bit more accurate than my senses, as it seems a few degrees can make a decent impact on the flavor.

The most popular notation of roast vs. color is what you are accustomed to using. Another alternative is to use a colorimeter e.g. RoastVision. There are several offerings which range all over the place in $$$.

The issue (well… my issue) is the subjective nature of identifying the exact color which represents each of those steps in the roast (C/C+/FC/ etc.). So I took it out of my hands and just use the scale adapted for the RoastVision. For the same beans the correlation between drop temp and color has been consistent. It isn’t falling-off-a-log easy in that you have to experiment with what taste you get for a given color, but once you get taste vs. colorimeter reading to your liking you can expect repeatability for that bean. My notations (Comments box) always include the color (med/med-dk/dk/v-dk/etc.) as well as the drop temp.

I suspect moisture content is related as well so I bought a cheap moisture meter but that’s a work in progress in terms of calibration- I’m not happy with repeatability of the moisture measurements much less any correlation with color/taste results. Yeah… maybe cheap wasn’t a good idea!

Bruce

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I believe bean density and processing method and age of beans also affects the colour of the beans. A similar profile, exact dtr, dt and drop temp has given varying colour levels in different beans.

I may be wrong, but an old natural bean (stored for long) of ours does not yellow and a cross section of a roasted one shows the inside to be lighter (consistent) than the outside. It isn’t scorched, tipped or unevenly roasted.

Little late here, but FWIW:

Of course how you get there matters a lot. That said, I generally think of these temperatures (all IBTS):

FC = 200C
light roast = 206C
medium roast = 212C
full city roast = 218C
SC = 223C

Didn’t want to write “dark roast” for 218C since dark is often used for roasts past SC. I like to use the tryer to look at and sniff the beans during the last minute or so of a dark roast, but don’t have the skills to make much sense of that information for the lighter roasts.

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@bradm - mine is very similar:

FC - 198 - 204℃
Medium - 215℃
Medium Dark - 220℃
Dark - 225℃
SC - 227 - 230℃