Roasting - Colombia to City+ [hoping for outcome of floral/sweet]

Looking for some City+ profiles 800g. I’m looking to roast sweet maria’s Colombia Urrao that mentions floral notes but given the wet process I’m wondering if I should go in the same way as a Guatemala or ease into it initially? My Guatemalas tend to taste more chocolate whereas my Ethiopias are Floral/Sweet. Would love a happy medium… Help?

Current Thoughts:
275 Preheat start at P7 or P8?
Roast Attempt: City+
*Will start at P8, leave drum speed untouched at D9 and perhaps attempt to play with the fan during drying phase then closer to 1st crack.

Bean: Wet Process Colombia: Colombia Urrao Heirloom Caturra

Not the 800g profile you’re after, but in case you wanted to do a 325g test this roast of last year’s SM Colombia Urrao Finca Las Palmas came out great (first roast starting from a cold machine, 15:00 preheat)

I got a rich smooth caramel toffee body with sweet grape juice. Such a nice bean. Hoping this year’s lot will be as good, since the SM cupping notes changed slightly.


Just jumping in here to say that @bradm has some great profiles to base yours on. I pretty much built all of mine off one of his. Good luck!


Awesome, been meaning to do a test batch. Mind if I probe and ask some follow up questions to this recommendation? I’m curious about in your thought process for this roast.

  • Selecting Power: What was the thought process for high power for such a small batch?
    Ex: <500g batch you started w/ more power at p7 and closer to 7 min dropped to p2

  • Selecting Preheat (c): My prev method was following the bullet recc which i threw out the door as I find i struggle in my preheat for big batches, generally setting too high causing scorching or tipping [saw cracks in the edge or the beans and hot spots as well as deformities]. To make best use of your example does it make sense to apply % so I know how much more I need to increase my PH for example or even power? [Note: I am at sea level [Southern California Coast] for external temp reference]

*BT & IBTS Chart:
both lines stat relatively 50c apart whereas I have found my lines to almost touch halfway through the roast and towards FC. Is the idea to keep these further apart?

I attached an image comparison of my last batch roasted of 500g. The taste for this was good, settles well on the tongue where its smooth in body but I think i am still lacking that fruit. I did get slight acidic impressions on the bigger batches but its too soon to tell considering i cup next day and do so for the next 5 to see how it changes in taste.

Thanks for the tip Brad!


Here’s my thought process, FWIW, debate welcome:

Power vs. preheat is a tradeoff - higher preheat needs lower power during the roast, and vice versa. Very high preheat could overheat the bean surface or scorch in the first minute or two of the roast. So I use reduced power for the first minute, a sort of soak, then raise power to achieve a reasonable peak RoR. Another benefit of this higher power early is that it gives you something to work with when you want to reduce power later in the roast. For example, if your target is to ride through FC at P4, using P8 early in the roast gives you 4 power decreases to play with as you manage the RoR.

I’m struggling right now to scale these profiles up to larger ~500g batches, so I don’t have a % or formula for you and would welcome any input. It does seem like larger batches need more fan than F3. Something tells me that our machines will produce the best coffee with larger batches, but I can’t demonstrate that yet. I’ve been really happy with some of those 325g results, so the bar is pretty high to beat them.

The BT and IBTS temperature curves should be closer together for larger batches. I think this is because the BT probe is better immersed in the bean mass and reads hotter, closer to the IBTS.

That looks like a very good roast. I’m guessing that the IBTS-RoR was pretty smooth through FC even though the BT-RoR spiked a bit? Please let us know if that roast tastes a little ashy or smoky, as you stuck with F3 all the way. Curious also to know if that was a chaffy bean, and if so, was F3 sufficient to clear most of the chaff? With 500g and F3 I was getting maybe 30% or more of the chaff in the cooling pan filter, only 70% in the chaff collector.


@bradm I’ve been playing around with 500g roasts using your 325g profiles as my starting point. I am using the same PH, but leaving the F2 on a bit longer than you did for your 325g roasts. Also using more fan midway to get more convection going (if I remember correctly it was in one of the Mill City season 1 roasting vids that he talked about convection is more efficient once maillard starts) and also dropping P towards the end. Seems ok so far with this roast. I may adjust the D down a notch for the entire roast. Need to play around with this some more. Believe it or not, so far one of my best batch was a Yemen at 325g more or less following one of your profiles but alas that was also the day that RT crapped on me and that profile didn’t get recorded! :roll_eyes: So I’m keeping some of those beans at least as a color reference.

I’m another user who has benefitted from @BradM tutoring from before I got the Bullet last fall. I have had a lot of success with Colombian beans and mostly Pink Bourbons.

Observing how the roaster behaves on preheat and using the fan has led me to conclude that there are functional differences with gas roasters. Most of my roasts are indeed 325 gm with occasional larger loads up to 1 pound. I have a couple of observations that anyone should feel free to disagree with, agree or modify for us all to learn.

I don’t believe that Bullet preheat temperatures based on IBTS measurements are comparable with gas roasters. Perhaps if we waited an hour for the BT probe to reach the IBTS temperature they would be functionally the same. Look at a gas roaster and the drop temperature is the temperature of the probe attached to the body of the roaster. The ROR flies up and then drops down where power (gas) and air flow control the hopefully linear decline in ROR. I half heartedly try to do this sometimes with limited success. I think getting to a target peak ROR early in the roast is important for controlling the middle phase and therefore sweetness and acidity.

Last for now, I’ve been playing with adapting IBTS temperature during a roast rather than time, as a milestone to change power settings. This has worked well and integrates with my above point about preheat and target ROR peaks. I’m not sure but it may be a method to help adapt from 325 gm to 500 gm charge weights.

@geoffreychilds this is very interesting. Do you have a profile you could share that illustrated your control of IBTS temp as milestone for adjustment to power?

Any of my recent roasts were done using temperature as a milestone to switch power settings. Here is a Colombian example that both Brad and I have roasted quite a bit.

What I did was to look a a former roast that I liked and checked the IBTS temperature when I switched from say P8 to P7. I do that for each power change. Lower preheat or overall temperature of the roaster stretches the roast a bit using the same IBTS temperature marked per changes. Higher preheat or overall roaster temperature makes things go quicker but with power changes consistent with the desired ROR decline. Fan change for me from F2 to F3 changes little and I use it to try to smooth out the decline without crashing. All this applies until approach t first crack. Monitoring development at the end of the roast is more intuitive. I hope this makes sense.


@blacklabs that link isn’t working for me for some reason. Can you give the roast name & date instead?

I’ve been trying to overlay with a good 325g roast, and reproduce the IBTS temperature curve with a 500g batch. That seems to require higher preheat, maybe 240C. But still not great results, so maybe your idea of using the same 210C preheat is the ticket. I guess the roast duration would be longer than with 325g?

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Brad - have you tried to use a PH temperature and power setting to match or come close to the peak ROR (BT probe) of a template 325 gm roast and only then match IBTS temperature milestone power changes? Perhaps that will separate a roast into 2 phases. 1 is the shove off the dock to get momentum and 2 is the glide into first crack where you want it to be for drop temperature and % development.

@bradm Here’s the direct link: Roast World - Cup, grade, and analyze your coffee roasts in depth
The link is for roast #22 on May 22. You’ll also see that roasts #19 to #21 on that same day used roughly the same profile. I chose to start with the same 392F to do a bit of “heat soak”. Yes the roast duration is longer for sure. Roasts #19 and #22 are my darker roasts last Saturday which was nearly 20 mins long.

I am also taking a bit of inspiration from @julio’s (Sweet Maria’s) “heat soak” profile that @bab told me about: Roast World - Cup, grade, and analyze your coffee roasts in depth (if this doesn’t work search for julio in “Users” on RW and look for his Brundi Honey Processed Kibingo Station roast on Oct. 14, 2019) I have tried to follow this profile more directly a few times and I find it works well actually for 500g at both a City+ and just after FC/FC+. Notice that he started at an even lower PH temp of 365F. FWIW, Bruce told me that Julio won 3rd place with that roast I linked to.

Would be interested to know how it turns out for you. I plan to do a bit of roasting this weekend, following similar to what I did last Saturday with D8 and maybe bump up the F a bit towards the end esp for a darker roast.

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Thanks @blacklabs those are more low-and-slow roasts for sure. I’ve been trying to avoid weight loss above say 14% lately (with mixed success), so would be very eager to hear how those roasts end up tasting. Maybe weight loss isn’t a useful metric after all.

Here’s my latest attempt at a larger batch of the wonderful Colombian pink bourbon bean:

The IBTS-RoR did not show the spike at FC that you see in the BT-RoR, so I’ve been ignoring that spike lately.

With a week’s rest the flavors in the cup were similar to the 325g batch whose profile I used as an overlay, nice smooth chocolate caramel body with fruity sweetness. But this larger batch also had a mild orange zest acidity that wasn’t present in the smaller batch, along with a little winey note in the cool cup. Overall the larger roast tasted lighter and brighter. Not sure if this is a reproducible trend and/or something to be expected. Work in progress.

I do the same and use the BT probe as my guide. Considering the long tradition in this, I think it suits best till we have more empirical, longer term data / experience

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@bradm I brewed those Yemen roasts last week and so far I’m happy with it, but as you know with Yemen it needs at least a week of rest for it to shine. I’ll see how they are next week, but so far the lighter roasts had a more floral cup while the darker ones has more chocolate in it (and would be good for espresso) and not much of that burnt bitterness.

Glad to see you might have found a profile that works, but I’m curious did you see some scorching at the high PH? 464F/240C is higher than I dared :slight_smile:

Hope to roast some Ethiopia Sidama before this long weekend is over…we’ll see (real-life work backlog is an issue…)

Good question on scorching, I’m concerned too. It deserves another thread?

The Rob Hoos video is pretty informative.

Pretty late to the game with my response but so awesome to see the thread below and reading what others have tried. @Brad I have attempted your roast and cupped Colombia [now obviously they are different beans] but I was going for possibility of extracting that fruit fwd note the description mention.

Bean: Colombia Urrao Jhon Alexander [recommended to roast at City-City]

Description: ‘Delicate and special light roast are graced with perfumed sweetness and aroma, clean acidic impression, soft floral hints, raw honey, and citrus brown sugar, accents of cherry & rosehip tea’.

Roast Link (using your prev Colombia roast tip]: Roast World - Cup, grade, and analyze your coffee roasts in depth

Roast Outcome: darker roast for sure, I felt I could’ve gone lighter on the PH and was concerned for going into 2nd crack

Cup Outcome (after a week rest): chocolate and no fruit fwd hints. I assume I did something wrong along the way.

*Going to try this again but perhaps lower PH…thoughts?

That looks like a nice roast, but it didn’t follow mine very well except for the drop temperature. Here are the two overlaid, with mine in the background:

Looking at the BT at time=0, mine was about 100C and yours was about 140C. That probably explains why you reached Yellow at 3:00 instead of my 4:40, and subsequently your FC was a minute sooner than mine. To hit the same drop temperature you had to drop almost 2:00 sooner than I did.

Did you start with a cold machine and preheat exactly 15:00? That’s what I did for this roast, so my machine was not as fully and uniformly preheated as it would be if this were the second or later batch of the day. I always roast only a single batch, so I developed this 15:00 preheat protocol and stick with it for consistency.

All that said, your bean may want a different profile than mine did. So you could use your last roast as overlay, and begin fine-tuning that one to bring out the fruity flavors. Maybe eliminate the short P8 segment, and use P4 instead of P5 in the last segment. Then dropping 2:00 after FC might give you a few degrees lower drop temperature. Just some ideas :slight_smile: as this is the fun part - making some changes and see what happens in the cup.