Gene Cafe Roast Level Issue

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

Postby mjseibert84 » Jul 05, 2019, 7:58 am

Hello everyone.

I have spent quite a bit of time researching this forum for assistance as well to make sure this question hasn't been posed before. My issue is that no matter what I do, I can't seem to get a roast lighter than a Full City (14.5-15.5% weight loss percentage). I have tried multiple profiles, multiple charge weights and nothing changes. My roasts consistently are full city or darker 1.5 minutes after FC begins (not after it ends). I consistently stop the roast 1.5 minutes after first crack starts. This usually corresponds to no more than 10 or so seconds after I hear FC stop.

So what's the deal? My questions are two fold.

1: Is it possible that FC is starting well before I can actually here it?
2: What seems to be the average length of time for FC on the Gene Cafe?

I hope I can figure this out because so far, after a few months use of the Gene Cafe, I have been very disappointed with results. My popcorn popper has provided better results.




Postby txxt » Jul 05, 2019, 9:12 am

Youre missing some really key information.

How much green beans are you loading each time to roast, what ranges? Are you preheating? How long in total does your roast take? What kind of beans are you using? When you stop the roast, are you using cool cycle or dumping w e stop?

And, finally, are you sure you know what FC actually sounds like?

Im hitting FC at around 9-10 mins on the Gene with a 230g load for reference.


Postby mjseibert84 » Jul 05, 2019, 12:00 pm

Sorry for the lack of detail. I forgot the bean info and didn't quite make what I've done clear (which is basically try everything I've seen on this forum from a range charge rates to preheating, etc).

I've roasted Panama, Columbia, and Vietnamese beans. Charge weights ranged from 200-230 following recommendations from this site, sweet marias, and others. I've tried preheating and not preheating (and different temps of preheating) and all it has done is change the time FC starts. Roast times are between 11:30 and 14 minutes, depending on charge weight and preheat. I noted hearing first crack between 10:30 and 12:30, again depending on input variables. All roasts are E stopped and cooled with external fan.

I am positive I know what first crack sounds like. Preheating definitely helps with hearing FC once it gets going but still hard to judge when it starts. My unit runs off 220v (roasting I n Vietnam where indoor ambient temps are currently 29-30C with extremely high humidity).


Postby txxt » Jul 05, 2019, 4:31 pm

Would it be easy for you to test your outlet to see if it's indeed outputting 220v?

If it's hard for you to be able to tell FC, maybe take a look at the topic you can find here on the HB forums on cutting wire to fit inside the drum of the Gene Cafe to prevent beans from impacting the glass. I haven't done it myself but I have removed the center divider from the drum to clean which would be one of your steps, wasn't difficult at all.

I wish I could help a little more but 2 out of the 3 beans you roast I'm wholly unfamiliar with (Viet/Panama) so I'm not sure what their FC would sound like. It's really interesting how much higher your ambient temperature is, but I couldn't comment on what exactly that would do to your roast time.

What happens when you stop during what you think is the start of FC??


Postby mjseibert84 » Jul 05, 2019, 11:54 pm

txxt wrote:What happens when you stop during what you think is the start of FC??

I will give this a shot. Since you asked this question I've started Y think maybe I am hearing 2nd, not first. I am use to the sound of FC in a popcorn popper but not the Gene. This could explain my issue. I will try a batch today and see what happens.


Postby Pingel » Jul 06, 2019, 4:06 am

Why don't you just stop your roast a minute before and see where its at? Who told You to roast a minute and a half after FC?

Your roast times seems a bit long IMO...


Postby mjseibert84 » replying to Pingel » Jul 06, 2019, 5:09 am

That's what I am going to do. I've always read that FC should take about 60-90s, or a little shorter, depending on charge weight. I've always stopped after I don't here cracking anymore, which happens about 60-90s after I hear it start.


Postby mjseibert84 » Jul 14, 2019, 7:27 am

So I finally got to a new roast of some natural beans from Panama, elevation 1400-1800 MASL. This is how I roastes, following someones profiles based on elevation and/or bean type.

Charge weight: 230g
Preheat 175C 5 minutes
Drop beans set to 243C: temp 125C when roast started
Lower to 236C at 9:30
Stop roast at 10:30

Plan was to stop right as soon as I heard "popping" to see if what I was hearing in previous roasts was actually FC. On previous roasts popping started around 10:30-11:30. This time I actually heard a few pops at around 9 minutes. So I dropped temp to 236C around 9.5 minutes and I stopped roast at 10:30 (few more remnants of popping when I stopped).

Result was still darker than what I typically see for a light roast. Weight after roast was 197.9g (about 13.9% loss). The was not uniform. I had everything from Quakers to super dark beans, and possibly some scorching. Here are picks I took under the best lighting I could.

Any recommendations? What level roast would you considered this? Any thoughts on why it's not uniform? I have a strange feeling this will taste grassy but we'll see when I cup tomorrow.





Postby mjseibert84 » Jul 14, 2019, 7:46 am

The pictures of the 6 beans were outside in the shade with a flash. I also have them with no flash (not sure what is better). I'm starting to wonder if the beans aren't very good quality. I removed quite a few crummy beans before roasting


Postby crunchybean » Jul 14, 2019, 8:59 am

Yea I got something for your change cup. Naturals are well known for varying/uneven roast colors. My recommendation is learning to roast by roasting, have an idea, try new things and taste your coffee. Spend time reading, online blogs, books, or videos, etc. Roasting can be the accumalive skill of learning all the different skills of the coffee industry. Brewing, sourcing/farming, what have you, all apply and affect how to roast a bean.

Roasting is hard but not rock science, time, patience and experience.