# Burnt beans? Need help with your roast?



## GUY C-P (Sep 16, 2019)

Hi guys, I need help with a prior roast.

It's not as easy to see from the photos but there are spots of oil all over this roast. Is this because I took it too high in temp?

It was one of the earlier (first) roasts I did on my Gene Cafe. The oil was certainly not present after I closed the container after 2 days degassing.

The roast was darker than I was aiming for and on my (miss guided wisdom) I had the Gene Cafe temp set to 245c, kept it there for 45 secs and then ended the roast. Development was very short given I ended the roast about 1

So is this an effect of taking it too high in temp?

Thanks Guy.


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## Rob1 (Apr 9, 2015)

You roasted into second crack.

Assuming you hit your set temp of 245c and held it for a minute after FC then that explains why you hit second crack.

In answer to your question (you already know the answer presumably), yes maintaining the highest temp through first crack will see the roast progress rapidly.

EDIT: Also can't really tell if there is any burning because the roast is so dark. You'd have seen the burning through development from green-yellow-brown-fc if there is burning.


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## DavecUK (Aug 6, 2013)

Guy, it's always good to give as much detail as possible....as a hint, your post contains about as little detail as it's possible to give. The photos are great though.


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## ajohn (Sep 23, 2017)

I buy 2nd crack beans with slight signs of oil and more comes out as they degas. They don't need to be that dark - if that is what you wanted. The problem is that beans can darken very quickly near this stage and get into 2nd crack raher quickly.

Not been able to use mine much due to kitchen work and a defunct garage that has had some extensive repair work done on it but after a couple of tries I went and bought some welders gauntlets to avoid using the cooling cycle.

Mine was bought used as well. I think I am the 3rd owner. Opening it up and vaccing it all free of dust made a significant difference to how it behaved. There wasn't that much dust in it.

John

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## DavecUK (Aug 6, 2013)

ajohn said:


> Not been able to use mine much due to kitchen work and a defunct garage that has had some extensive repair work done on it but after a couple of tries I went and bought some welders gauntlets to avoid using the cooling cycle.


 Best to let it run the cooling cycle John or you affect the units lifespan....


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## ajohn (Sep 23, 2017)

Interesting as I would have thought forced cooling of the element would have shortened it's life. My suspicion is that the prolong cooling cycle extends the roast and it needs accounting for so easier to tip out and cool separately. No problem running it for a short time. Kanthal if that is what they use does expand as does nichrome.

There are a few comments about on using them such as not preheating that may or may not make sense as air flow with beans out will be higher.

At some point I will be sticking 2 thermocouples in to see what does go on and also maybe see how complex the temperature control is.

John

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## GUY C-P (Sep 16, 2019)

Hi All,

I cant express enough gratitude to you guys helping! @DavecUK, absolutely right and i will try and provide a little more (this is not an odd game of pictionary)!

So second attempt at the same beans (Columbia Tolima). Lower weigh in to avoid the high chaff clogging the GC.

General thoughts

The roast was un-even. some good looking (larger beans) with a small bit of silver skin vs some (typically smaller beans) that look fairly dark. See the pics attached. There was still a lot of silver skin covering the whole bean at a guess 5% of all the beans.

Roast Details (as available on the Gene Cafe)

Weight in: 215g (that all i had left) volume was around 275ml (in the jug)

Pre Heat to 150c

Target temp 1: 238 from start to FC start plus 1min 30

Target temp 2: 233 until end.

Weigh out: 187g volume was around 400 ml

Dry end was 5:45 min/sec

FC was 11:04

[Temp down to 233 @ 12:30]

Roast End was 13:35

When i finish the roast i put it into a colander that is sunken in to a card board box that is attached to the hoover to draw air through the beans until cool. this is usually done in about 2 mins or just over.

Notes through the roast

4:00- Beans to Pale Green

5:35 - Beans to yellow

6:00 - Yellow Brown

8:00 light brown

10: brown (still with quite a lot of chaff)

11:04 FC start

[c.12:30 temp to 233]

13:35 - End & cooling

Is this difference between beans some what out of my control given the difference between bean size?


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## DavecUK (Aug 6, 2013)

Don't preheat, use beans with a more consistent size, try dropping the temperature a little earlier after 1st crack starts. Check chaff wiper is moving freely and that the grate is clean at the end of the drum. Check the chaff collector box doesn't have a blockage or a load of chaff caught in it. Take it apart to check if required. Check the intake under the Gene isn't clogged


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## Rob1 (Apr 9, 2015)

The set temp is irrelevant. Useful information would be the actual temp at the various stages as the roast progresses. Where did you buy the greens and how old are they?


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## ajohn (Sep 23, 2017)

This is my last one. Too dark









230C set on the Gene. No preheat and Gene as it comes other than vaccing it out. Lots of first crack heard, maybe too much but strongly suspect they would have been lighter if I had tipped them out sooner. The colour variation is more down to the photo than the beans. The colour is a little darker than they were.

230C as beans are unlikely to roast to 1st crack at temperatures below that. It just allows a little temp drop in the chamber but not much. Circa 10C.

Columbia FincaSofia. Never drunk it so can't compare with my roast really but taste ok but not something I would usually drink as a bit banal. Other than sweet acidity being lacking more or less matched tasting notes - that lack may be down to me.

Afraid I didn't note time. More interested in 1st crack and colour. I've bought some bits to fit an energy regulator and thermocouples but not got round to fitting yet.  As things are tricky in that direction at the moment and for a while yet I have bought a fold up hobby table.

230C+ may take beans into 2nd crack. The time from 1st can be rather short. The fact that I used 230C could be too high if Gene is used this way.

Before vaccing it out I tried all of the methods mentioned in the tutorials and all resulted in very black beans. Also needed to dismantle the chaff chamber and clean it out  also a bit of filing as it had distorted a bit. Not being able to really hear cracks wrecked some roasts as well.

I mentioned preheat because some one does and gets decent results. Pretty sure they showed up on here and disappeared as soon as some one told them they mustn't do that. It sounds like it speeds up roasting. He has a video on youtube somewhere and uses a cardboard tube to listen for cracks. UK poster.

John

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## Rob1 (Apr 9, 2015)

Not all beans are the same. 230c might work for one but not another; one might rush into second crack and another might struggle to get there in a reasonable time.

Preheating doesn't really do anything but shave a small time off the start of the roast. Whoever might well have got good results preheating but it doesn't mean you will with your beans or that it was necessary to get good results at all. I've roasted beans from pretty much everywhere in the gene with good results without pre-heating. The only ones I've had trouble with were a suspicously green batch from Indonesia (i think) and I suspect they weren't dried properly.


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## GUY C-P (Sep 16, 2019)

So it's the weekend and time go get a little roasting in.

On the right *Ethiopia Limu Gr2*

charge in 250g

Target temp 1: 238c

Target temp 2: 233c

Dry End: 5:15, FC: 12:30 End: 13:15

min:sec - Temp C

0:30 - 83, 1:00 - 96, 1:30 - 111, 2:00 - 129, 2:30 - 143, 3:00 - 153, 3:30 - 163, 4:00 - 171, 4:30 - 184, 5:00 - 189, 5:30 - 194, 6:00 - 199, 6:30 - 204, 7:00 - 207, 7:30 - 211, 8:00 - 214, 8:30 - 219, 9:00 - 222, 9:30 - 224, 10:00 - 227, 10:30 - 230, 11:00 - 232, 11:30 - 234, 12:00 - 237, 12:30 - 238, 13:00 - 233, 13:15 - 233

Weight out 216g

On the left, *Tanzania AA Mbeya Ndugu*

charge in 250g

Pre heat around 80c from prior roast

Target temp 1: 238c

Target temp 2: 233c

Dry End: 6:30, FC: unsure, End: 16:30

min:sec - Temp C

0:30 - 98, 1:00 - 125, 1:30 - 143, 2:00 - 157, 2:30 - 163, 3:00 - 177, 3:30 - 185, 4:00 - 191, 4:30 - 198, 5:00 - 203, 5:30 - 207, 6:00 - 213, 6:30 - 216, 7:00 - 220, 7:30 - 223, 8:00 - 227, 8:30 - 230, 9:00 - 234, 9:30 - 237, 10:00 - 238, from 10:00 until 15:00 - 238, 15:30 - 233, 16:00 - 233, 16:30 - 233 End

Weight out 211g

i do find it very difficult and/or I can't pin first crack some times.

how do there roast sound guys? Should I have the temp set to 240 and then keep the temp when I hear first crack?

I did another roast after this of Malawi AA Pamwamba beans and I again only had temp set at 238 and didn't identify first crack! I defiantly heard some solo cracks but noted 12:00 mins and 14:00.

I defiantly heard it on the Ethiopia beans very clearly, is my temp now too low and therefore not high enough for the other beans, as I know it will vary.

Do there roast times seem right for a light/medium roast?

I took the Malawi beans to 16:00

Thanks Guy

thanks Guy.


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## Rob1 (Apr 9, 2015)

Your roasts are progressing too quickly and aren't even. A higher temp will cause more problems. With an unmodified roaster things are harder especially when aiming for a light-medium roast where the beans are allowed to develop just clear of first crack or the roast finishes when it ends. You'll want to extend your roast time, don't worry too much about that as the beans spend longer at a lower temperature compared to a larger drum roaster. You don't want to drop the temperature so early that you extend the time from yellow to fc too much but you do want to make sure the roast is progressing evenly into FC. With a modified gene I'd use a lower power after the drying phase to let them develop evenly, unmodified the only choice is to limit the max temp to something like 210c and wait for the drying to end and yellowing to start before letting it go up to 235 or whatever. I'd say with a lighter roast you'll need to extend first crack itself -- in your first roast it isn't even a minute long -- to develop the coffee properly. I would only be looking to end the roast two minutes after FC start and would adjust based on taste from there. With an unmodded gene again you'd do this by dropping the temp as you move in to FC which you can predict by colour change, moisture coming off the beans, smell and a small amount of smoke...when you're in FC you'll have a lot more smoke. Without being able to hear FC it can be difficult to know when to decrease the temp to extend the roast but for logging purposes it shouldn't be difficult to identify rolling FC from smoke output alone, but then after that again it can be difficult to identify when FC ends.

I would expect both of those roasts to taste acidic/sour, thin and generally weak/underwhelming with burned notes...if not and they taste great then ignore the advice and carry on.


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