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Help me get rid of scorched beans / uneven roast

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So, I’ve been using a modded Gene Cafe now for a few months, and recently put two kilos through.

 

Every single batch came out with scorched beans. I’ve tried lowering the amount of beans in the chamber, I’ve tried a gentle rise, I’ve tried not so gentle rise. I’ve tried 250g, 230g, 220g, all to no avail.

 

One thing I’ve noticed though: I noticed some chaff accumulation on the chamber’s exit grille (I always clean before and after each roast) and I am starting to think all of this may be due to a poor air flow on the Gene.

 

I’ve checked the air filter gauze, and it’s so clean you can actually peep through the holes and see the inside of the Gene.

 

Could I have a duff fan? Is there a way to test if my fan is blowing enough air?

 

Thanks in advance!

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I've been on the brink of starting this self same thread for the last few weeks, after trying all the above fixes to no avail....

So frustrating!

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You're going to have to provide more information. What is a gentle rise etc? What temp does the Gene reach? When do you notice the scorching? Some beans can take a lot of heat and some can't so bean size and density is relevant. In run the gene at full power until 230c and then switch in the dimmer at 1150w (at 245-250v) and I don't get scorching. If you run a batch and your air flow isn't good the element will switch off before reaching temp.


ACS Minima (Beta) -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

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You're going to have to provide more information. What is a gentle rise etc? What temp does the Gene reach? When do you notice the scorching? Some beans can take a lot of heat and some can't so bean size and density is relevant. In run the gene at full power until 230c and then switch in the dimmer at 1150w (at 245-250v) and I don't get scorching. If you run a batch and your air flow isn't good the element will switch off before reaching temp.

 

Thanks Rob.

 

Gentle raise: I’ve tried full power to 220C, then hold there for 1m (I found that 1100W holds the temp nicely), then full power to 230C, hold for 1m, and then full power again to 235-238 until F.C. , back to 1100W, stay there until desired colour and cool down.

 

I’ve also tried 220 -> 230 -> 238 without the mod.

 

I’ve also tried gradually ramping up: from 7min into roast, gradually increase the wattage from 1100 to 2000W. That was rubbish: hard beans, baked, awful. Yet, scorched and uneven.

 

I roasted last Brazil’s naturally processed and Peruvian washed.

 

The element never switches off during ramp up or at all. I only noticed switching off once at the end of the roast, very briefly, snd that’s when I noticed the chaff blocking the exit of the chamber. I’ve subsequently roasted after that and never noticed the element turning off.

 

Scorching: I noticed that, after they turn yellow and becoming brown, some are more brown (roasted) than others. When the roast is finished, I notice that they all have some kind of scorch marks.

 

What intrigues me is that, when I see some posts on the “today roast” thread and the beans are so even, and those guys are using the Gene - I think I’ve seen a few from you too - the roast looks great, and mine don’t even look anything like it. I think Iroko just uses a stock Gene Cafe, just leave the Gene to do its job and what I see are very even beans. I tried that myself, and the result was very different.

 

Ps: I’m happy for a suggestion of beans and a profile to try it out :-)

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It's been a while since I roasted Brazils and I think I've only ever had 1kg of Peruvian. From what I remember Brazilian beans tend to burn easily and require a more gentle approach to roasting but it will vary depending on altitude. They should be rated as hard or soft beans or have the altitude detailed on the packaging/description. Some beans roast unevenly with a wrinkled looking surface. I've had plenty like that and they look uneven but then suddenly even out in the drum. To eliminate scorching I don't know what to suggest other than limit your maximum temperature and control your wattage. Make sure it isn't skipping up as you watch the beans. What's your voltage?

 

I'm not sure why you're holding at 220c or 230c etc for 1 minute. I used to do permutations like switching the dimmer in and out, using different wattages at the different stages, but it didn't help. My roasts have improved with just running either with declining profile like 1150w until 165c (BT) 1130w until first rolling 1100w until first end 1080w-1050w until end of roast. Or with running at full power and switching the dimmer in to run at a target ET with a target wattage depending on the roast depth and first crack length I want. I struggled with scorching on a Panaman bean a while ago and I had to use something similar to the above profile as the scorching as the beans yellowed -- they couldn't take the heat at full power. I always struggled to get anywhere close to second crack with them without burning/scorching. It's frustrating but fighting against your roaster is impossible.

 

Have you recorded the times for your roast?

 

You let the temp hit 220c then switched in the dimmer at 1100w and held it for 1 minute. Then full power to 230c and held it there how? 1100w again? Then full power again until FC at what time?

 

Give the following a spin:

 

Full power until paling (approx 4:30-5:00 minutes).

1150w until Browning.

1130w until FC rolling.

1100w until FC end.

1080w declining after 30 seconds to 1050w until roast end.

 

That should take you through to a finish BT temp of about 230c so Full City+. You're going to have to adjust depending on whether you get scorching again (start from 1130w) or if it takes ages to reach first crack and it progresses slowly (1150w until start of FC (you smell it before you hear it)). If you want to hit second crack you might not lower to 1130w on rolling you might just let it run through and drop to 1100w as the pops slow down. The gene readout 'ET' (it isn't the ET) will also determine when you switch wattage if you have found you get scorching when going above a certain temp. I get very slight scorching on El Salvador Red Bourbon at 235c so I limit it to 230c and alter my power to stop it from rising above that. I never let the element switch off (it's set as high as it can go to keep it out of the way).


ACS Minima (Beta) -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

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Thanks @Rob1.

 

I’ve also followed your decreasing temp profile from Today’s Roast, and, the results didn’t look any encouraging, at least with the beans I’m using. I’ve bought 1kg of Colombian Suarez from Rave so will give that a go next.

 

I’ll give it a go again to the decreasing profile and will report back.

 

My voltage on the last roast was 239 / 240, but it is usually 237 / 236.

 

I did monitor the temp raise, minute by minute too. Seems fine.

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If you've already done what I've described above there's no point trying it again as your results will be the same. Voltage is low if you're on a 240v element so I'd think you'd struggle to increase temp rather than have to deal with it getting too hot too fast. The key to stopping scorching is to not roast too hot and/or fast. If you aren't getting scorching early in the roast logically you're getting it when you increase the temp above 230c. The uneven colour as the roast progresses could be due in part to your permutations and just the way the beans roast.


ACS Minima (Beta) -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

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@Rob1.

 

Could it be that the “Full Power” can be scorching the beans? I could try as you suggest keeping steady at 1150W and then lower as I get to first crack as an experiment.

 

My worry is that I might have baked coffee instead of roasted coffee at the end.

 

And indeed, I do have a 240V element.

 

Anyway, I’ll try that and see what happens.

 

Question: do you get chaff accumulating on the exit grille of the chamber? How much do you load it with? 250g?

 

Thanks again.

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250g I don't really. If you've got a natural you'll get more chaff and should lower the batch size. Full power won't scorch until the drying stage has ended (as the beans pale just before turning yellow). You won't get baked so long as the temp of the bean continues to rise.


ACS Minima (Beta) -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

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So, I’ve been using a modded Gene Cafe now for a few months, and recently put two kilos through.

 

Every single batch came out with scorched beans. I’ve tried lowering the amount of beans in the chamber, I’ve tried a gentle rise, I’ve tried not so gentle rise. I’ve tried 250g, 230g, 220g, all to no avail.

 

One thing I’ve noticed though: I noticed some chaff accumulation on the chamber’s exit grille (I always clean before and after each roast) and I am starting to think all of this may be due to a poor air flow on the Gene.

 

I’ve checked the air filter gauze, and it’s so clean you can actually peep through the holes and see the inside of the Gene.

 

Could I have a duff fan? Is there a way to test if my fan is blowing enough air?

 

Thanks in advance!

 

My gene is standard, I get chaff build up at exit grill but It always gets blown through. Does the chaff in yours not get blown through ?

 

I do get a few scorched beans but nothing bad.


Londinium I / Monolith Conical / Macap MC4 / Cormorant CR600 Roaster

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My gene is standard, I get chaff build up at exit grill but It always gets blown through. Does the chaff in yours not get blown through ?

 

I do get a few scorched beans but nothing bad.

 

They do, but at the end of the roast I still have chaff sticking there.

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I have no chaff left at the end of roast, is there enough chaff to block the air flow at the end of your roast.


Londinium I / Monolith Conical / Macap MC4 / Cormorant CR600 Roaster

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I have no chaff left at the end of roast, is there enough chaff to block the air flow at the end of your roast.

 

That’s what I’m suspecting Iroko. It’s getting too hot in the chamber, without a good airflow, and the beans are getting scorched.

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Check the flappy thing (technical term :) ) is correctly cleaning the chaff away from the vents. The only time have had this was when I had somehow managed to stretch the round spring wires whilst cleaning the chamber separator. Quick call to BB and Claudette sent me some little spring things to replace the stretched ones. PITA to fit (needle nose fine pliers a must) but once done problem solved. You could also replace the chamber separator here then would allow you have one clean ready to go and one in use (cafiza works a treat on these)

Whilst this may not be the answer assuming you unscrewed the chaff collector to clean behind the screen and vacuumed the underside of the gene where the dust screen is on the air inlet, it might get you some of the way to dealing with the chaff issues if nothing else.

John


Roasters: BB Dalian Amazon 1kg -Power contolled GeneCafe 101- 106Kg of greens - Tonino

Espresso: Londinium L2 - Gaggia G105 - Silvia v3 Mr.Shades PID'-d - Faema E92a2 (Project) - MyPressi Twist - VST baskets / Motta Europa (350/500/750ml) - Torr Ti 58.55 & Goldfinger flat 58.4 TiBlack, Pullman 51.4 - Acaia x2

Grinders: Flats: Compak R120 - NS Mythos plus Conics: Compak K10PB - Lido 3

Brewed: Behmor Brazen - Moccamaster KBGT471 - Aeropress - V60 - Cona model D - Clever - Mizudashi - 8-10 + 6 cup Chemex

Water: BWT Bestmax V Refrac: VST III

and a Puq Press not in a pear tree..

 

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Check the flappy thing (technical term :) ) is correctly cleaning the chaff away from the vents. The only time have had this was when I had somehow managed to stretch the round spring wires whilst cleaning the chamber separator. Quick call to BB and Claudette sent me some little spring things

John

 

These?

 

dd602c96728ddc4e081d8876f420ed84.jpg

 

Just checking, they don’t have any spring effect do they? They are just rings to hold the flap in place?

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Yes, hard to tell from the picture but are these solid rings or coiled wire similar to a key ring holder?

John


Roasters: BB Dalian Amazon 1kg -Power contolled GeneCafe 101- 106Kg of greens - Tonino

Espresso: Londinium L2 - Gaggia G105 - Silvia v3 Mr.Shades PID'-d - Faema E92a2 (Project) - MyPressi Twist - VST baskets / Motta Europa (350/500/750ml) - Torr Ti 58.55 & Goldfinger flat 58.4 TiBlack, Pullman 51.4 - Acaia x2

Grinders: Flats: Compak R120 - NS Mythos plus Conics: Compak K10PB - Lido 3

Brewed: Behmor Brazen - Moccamaster KBGT471 - Aeropress - V60 - Cona model D - Clever - Mizudashi - 8-10 + 6 cup Chemex

Water: BWT Bestmax V Refrac: VST III

and a Puq Press not in a pear tree..

 

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Yes, hard to tell from the picture but are these solid rings or coiled wire similar to a key ring holder?

John

 

They are coiled like a key ring holder.

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Then they may be stretched enough to interfere with the way this paddle affair works getting caught and then on the down swing coming in too high to break the chaff up, (if you watch it when there is chaff there you will see what I mean) and it does sound like it is not making contact enough.

 

The only way you will know if it is this or not is to try either replacing the rings or the chamber separator.

 

John


Roasters: BB Dalian Amazon 1kg -Power contolled GeneCafe 101- 106Kg of greens - Tonino

Espresso: Londinium L2 - Gaggia G105 - Silvia v3 Mr.Shades PID'-d - Faema E92a2 (Project) - MyPressi Twist - VST baskets / Motta Europa (350/500/750ml) - Torr Ti 58.55 & Goldfinger flat 58.4 TiBlack, Pullman 51.4 - Acaia x2

Grinders: Flats: Compak R120 - NS Mythos plus Conics: Compak K10PB - Lido 3

Brewed: Behmor Brazen - Moccamaster KBGT471 - Aeropress - V60 - Cona model D - Clever - Mizudashi - 8-10 + 6 cup Chemex

Water: BWT Bestmax V Refrac: VST III

and a Puq Press not in a pear tree..

 

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@johnhealey, @DavecUK, @Rob1

 

So today I noticed chaff accumulating on the exit grille of the roast chamber. The flap was swinging happily, but not doing much.

 

So, I removed the chaff collector all together and.... Voila. The chaff started to clear away from the exit hole in the chamber quite rapidly.

 

I then did another two batches to confirm my theory, and yes, I can visibly see the grille pretty much clean thru the roast and also there doesn’t seem to be much chaff left on the beans themselves compared to before, a considerable improvement for sure.

 

I hoover the chaff collector after each roast, and also brush it. As far as I can see, there are no blockages.

 

What do you guys think this could be? I’ve mentioned you in this post as you guys have a lot of experience with this roaster and roasting in general.

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The bean you are roasting has a lot of chaff to shed (to be expected really with a natural process) and you need to reduce your batch size.


ACS Minima (Beta) -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

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The bean you are roasting has a lot of chaff to shed (to be expected really with a natural process) and you need to reduce your batch size.

 

But why removing the chaff collector solves the problem?

 

Also I tried with a “fully washed” process bean. Same thing.

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You've previously confirmed that you've dismantled the chaff collector and completely brushed it out (from behind the metal grate), or am I mistaken? I thought somebody already mentioned doing this?...if you have then by removing the chaff collector you remove all resistance so the fan can clear the chaff more easily. That's assuming you've already followed the advice given to you of cleaning the chaff collector.


ACS Minima (Beta) -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

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You've previously confirmed that you've dismantled the chaff collector and completely brushed it out (from behind the metal grate), or am I mistaken? I thought somebody already mentioned doing this?...if you have then by removing the chaff collector you remove all resistance so the fan can clear the chaff more easily. That's assuming you've already followed the advice given to you of cleaning the chaff collector.

 

Chaff collector is completely clean throughout.

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You've dismantled it by unscrewing the metal screen inside it? If so then the answer is in removing the chaff collector you've removed the small amount of resistance it was giving the fan, effectively making it that bit more powerful to clear the chaff. The solution (assuming you don't want to collect the chaff by some other method) is to reduce batch size.


ACS Minima (Beta) -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

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You've dismantled it by unscrewing the metal screen inside it? If so then the answer is in removing the chaff collector you've removed the small amount of resistance it was giving the fan, effectively making it that bit more powerful to clear the chaff. The solution (assuming you don't want to collect the chaff by some other method) is to reduce batch size.

 

I did not remove the screws. I just hoovered from the bottom and from the top, by taking the upper part of the collector out.

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