Roast Profile Advice…

Would love some advice.…

Context: I have done hundreds of roasts on a Gene Cafe and have recently switched to a v1.5 bullet. Trying to figure it out and struggling. I’m about 50 roasts into and for my preferred batch size I feel as though I have a semi smooth declining ROR. The coffee though is tasting rather flat and lacking flavor. I also am slightly clueless on final drop temp or development time. I have read loads from Hoos and Rao and home barista forums, but no one seems to give a good range of an area to start. So it’s entirely possible my dev times are too short or my drop temp is too low. I am aiming for a light roast highlighting origin flavors and acidity. This roast is for a dense Ethiopian Guji G2 bean.

Thanks in advance for any help you can provide!

Have you tried using less fan speed? I’ve seen too much fan produce flat flavors (but beautiful curves). You would need to control RoR with power changes, which can take 30 seconds or so to show an effect in the curves. So you have to anticipate and apply changes in advance, which takes some experimentation. Try limiting fan to F2 or F3, perhaps up to F4 post-FC for a natural process bean. Hope this helps! - Brad


Would you recommend continuing my low temp soak method or should I abandon that? Trying to figure out if the timing of everything is good and I just need to lower fan speed and lower power or if I should try to speed up the roast since lowing the fan speed will naturally do that.

And would you keep the preheat at 401 for 400g or increase it?

Your overall profile, preheat, weight loss, development time, all look reasonable, at least for a starting point for a new bean. I guess the coffee isn’t terrible, just a little plain tasting? That’s what I found from using too much fan. So less fan is probably worth a try. If you do, please let us know what you think.

I also like to use lower power for the first minute, because I think there is a potential for early scorching. I check for early scorching using the tryer once in a while, especially for the first roast of a new bean. Rob Hoos has an interesting Roasting Defects video that discusses this. But I honestly haven’t seen it more than once or twice. Maybe others will add their experience.

Edit: Just noticed you’re roasting an Ethiopian. These do generally like a hotter, quicker roast. This one came out well, for example: Roast World - Cup, grade, and analyze your coffee roasts in depth


Sounds almost like baked coffee? I think 10 minutes could be a bit long for a medium roast (that’s not a full 1 kg batch). Less fan should get you there.
Maybe even smaller batches while you figure it out? Do Ethiopian coffees from other roasters taste good to you?
(And perhaps add Morten Munchow to your reading list.)

I will try less fan and report back!

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I am wondering if it is baked as well. Typically Ethiopians are my absolute favorite. I love wild and experimental coffees. My struggle is dialing in this particular roaster. I know the beans are great, I have roasted and sold loads of bags from this particular lot of Ethiopian Guji beans and I regularly make excellent pour overs and espressos with it. But dialing in the roast on this new roaster has been quite the challenge. And the tough part is with a Gene cafe there is no real data to go on. I just happened to find a temp and time on that machine that worked well for this bean and I’m new to this journey of building and developing a roast profile.

I will add that author to my list!!

FWIW, this recent one for me for an Ethiopian natural turned out quite well for me. It might be a bit darker than you want (in which case I’d drop the beans sooner). It’s about a 1lb batch with a drop temp of 430F on the IBTS. I use a bit of heat soak at the beginning and like Brad I stayed with F2 and F3 for most of my roast until towards the end to get the chaff out and not let the roast run into SC. Also… I don’t get too hung up on a smooth RoR :slight_smile:

EDIT: I came from a FreshRoast which also had no data and completely different from the Gene. It took me a lot of roasting and learning from Brad to get to where I’m finally comfortable with what I’m doing at the 1lb and 1kg batches (2 yrs and 120 odd roasts later).


im not able to see your curve. youll have to use the embed function on the curve itself

Try this

got it!

I have redone a few coffees and tasted them. They have definitely improved however they are still lacking. I will include some roast profiles of a Washed Honduras La Navi and a natural Ethiopian Guji blend. Any critiques or advice you could give would be super helpful. The Ethiopian is good but slightly lacking overall flavor, and the Honduras is hollow and drying on the tongue.

Honduras: Roast World - Cup, grade, and analyze your coffee roasts in depth


On the 18th it looks like you carried a lot of power into FC and a few of the RoRs crashed, But on the 25th you really fixed this, cutting power earlier and obtaining some nice looking curves (per Rao, anyway). Some of the roasts are pretty light, so they might take a week or two for the flavors to peak, but sure would be curious to hear how you’d compare the flavors from the 18th and 25th sessions, and which were best.

The roasts from the 25th felt much more controlled. I intentionally added 30ish seconds to Malliard Phase and 30-40 seconds Development time while maintaining a lower final drop temp. I did this cause of the roasting errors I tasted from the 18th. They seemed to go pretty great though I do wish some were a little smoother ror curve. Once I taste todays roast I’ll do a clear write up comparing both!

Agree with you on the scorching. In my case it was tipping and I managed to eliminate that by reducing P to 4 after charge and going back up to 9 after turnaround. That little bit of soak has helped solve my tipping issue.

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A little off-topic, but did anyone else purchase Rob Hoos’ recent .pdf on tipping?

Out of respect for Rob’s work I won’t divulge his conclusion, but one of the roasters used in the study was the Bullet. The guide is quite useful and to the point. Worth the $5, IMHO.


Just got done with modulating the flavor profile of coffee. Excellent book though I wish it had more specifics. Discusses a lot about variance from baseline and little about what a baseline might be. Will definitely but and read his tipping book though!

Thanks for posting your efforts. I too never get enough heat early in the roast to get the profile I want. I can tip/scorch but can’t get a max ROR much over 20 even with low weight charges. I have to stay on higher heat too long which starts a train wreck of trouble.

Roast duration is an issue when roasting these hard bean Africans. AS AN EXPERIMENT I tried a low/slow roast on my Huky gas drum yesterday with a super fruit bomb Colombian Anaerobic. I usually roast this hot and fast with a drop from 8 to 8:30 but dropped this at 11:30. It mirrors to some degree what happens in the Bullet. Even though my ratios were decent (53-31-16) with a 10C delta over its 1:51 1C the roast lacks the aliveness it has when short.

How is your 3/25 Sidamo?

An analysis breakdown of some my most recent roasts.

All of the Honduras 3/25 roasts were flat, green, and grassy. I do believe it is lacking development and also lacking overall time in Maillard phase. I am proceeding to reroast it with more development and more time in maillard while keeping a similar finish time.

Guatemala 3/25 was underdeveloped. That is intended to be my most developed roast so that one will be scrapped.

Both Kenya 1 and 2 3/25 were good. Kenya 1 provided a nice sweetness while maintaining the sparkling acidity of the coffee. Tastes strongly of tropical fruits, pineapple, and apricot. Solid roast.

Ethiopia Guji Taro 1 3/25 was flat. No other way to describe it. Reroasting it tomorrow with shorter development time to peel back and reveal the brightness of the coffee, and going to spend more time and maillard phase while maintaining a similar drop time.

Ethiopia Dur Feres 1 3/25 was a beautiful roast. This has been one of my favorite coffees on my last roaster and it’s wonderful on the bullet. Smooth tart notes of cherry juice with undertones of strawberry and sweetness coming from darkened sugars such and brown sugar or rose sugar. Ever so slightly delicate and complex but still maintaining body and acidity. This coffee was great in a variety of espresso drinks but I loved in high temperature pour overs with an Orea V3 flat bottom brewer. Provide excellent sweetness cause it’s a flat bottom but maintains fast flow like a V60.

Ethiopia Sidamo 1 3/25 was great. This particular coffee I aim to make my introduction to beautiful fruity Ethiopian coffees. As such I developed it a little more even though the whole roast was bit faster. This resulted in a sweet Ethiopian coffee that presents flavors of darker fruits such as blackberry and plum with undertones of vanilla. It has a slightly muted acidity to make it more drinkable for those unaccustomed to funky Ethiopians. Altogether a great bean and a solid roast. Unfortunately this bean does have a bit more quakers than normal but that is because it is only G3 not G2 or G1 so it has more sizing variation.

This is my manifesto of current findings. I will be cupping and brewing 3 new variants of Honduras La Navi and shall report back my findings. I will also roast more Guji Taro tomorrow in hopes to finally let this strawberry coffee shine.

Thank you all for the help and wisdom. Hoping this can help someone in the future!

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