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Drying Phase in my Gene Cafe
Ryan
I found that pretty much everybody recommends a 5 minute drying phase at 300? with the Gene Cafe. I'm not trying to refute that in any way, I'm just trying to learn my own GC roaster and put together some generic profiles.

When I try the 5/300 drying phase, my beans are still very much green at this point. In fact, if I keep it going at 300?, I get yellow beans closer to 8:00 in. Is this normal or is the goal to have yellowing at that 5 minute mark? I suspect that my roaster is particularly slow, which wouldn't surprise me given its age.

I pre-heat my drum to 350? before adding the beans. I figured out that if I use a 6 minute 401? drying phase, that is the point where I'll have yellow beans. I can use 5/300 for decaf, at which point I'll have yellowing.

I'm just wondering what other roasters and Gene Cafe owners think about this?
 
Ryan
OK, a more direct question to other Gene Cafe owners... If you preheat your roaster then do a 5 min / 300? dry phase, are your beans still green in color at this point?
 
Steve Egge
YES .. on my roaster I turn the temp up to 464 and hit yellow in 4 minutes from when I crank it up (if I dry for 4 at 300 I hit yellow at 8 and tan at 9.5) ... I don't think 300 degrees is enough to turn the beans yellow ... certainly not at 5 minutes ... Just my experience. I do dry at 300 to try to even all the temps out per roast .. but just do 4 minutes or so ... no problem with 5 minutes ... just want to get on with it ... YMMV ... Steve
Santoker Rev 500, Baratza Vario-W, HG-One, Bunn Trifecta MB, AeroPress, Londinium I
 
Ryan
Interesting, thanks Steve. So, if you dry at 300 for 4 minutes then crank it up to 464, hit yellow around 8 minutes, when do you typically hit 1st crack?
 
Steve Egge
I hit first crack between 12 and 13:30 just about all the time.

Steve
Santoker Rev 500, Baratza Vario-W, HG-One, Bunn Trifecta MB, AeroPress, Londinium I
 
Steve Egge
Just ran an "Experiment" ...
I preheated the Gene for 10 minutes at 350 degrees ...

Stopped and added green beans and started roasting at 300 degrees for 5 minutes...
Stopped roast ... didn't dump beans but placed upright in holder with top open
interted a temp probe into the beans ... it was suspended off the metal grid and held in place, it took a while to come up to temp but highest bean temp reading was 217?F

Bean weight loss was 227 --->221.9 or 2.25% weight loss during this 5 minute drying.

This finding makes me feel comfortable with this drying period ... that is the beans are not stalled and are still absorbing heat ... slowly.

I plan to do a bit more of this but am waiting on a part to help with the testing.

Steve
Santoker Rev 500, Baratza Vario-W, HG-One, Bunn Trifecta MB, AeroPress, Londinium I
 
Bmb
Trying out the Claus Fricke Double Roasting (or two stepped) method.
In a nutshell: the idea is to dry the beans, at 160C for 8:5 minutes in the first step, dropping and cooling the beans down to room temp (10 to 40 minutes). No roasting takes place during this step, only drying. In this step alone I get around a 3,5% weight decrease.
Especially useful with recently harvested beans, that may have a higher water content, which is quite frequent here in Brazil.

The second step is roasting, and here he recommends a 5' warm "loading" phase, and after that doing your usual roast (without the drying phase, of course).

The taste difference, IMHO, with normal roasting, is that it manages to get more "varietal characteristics" (more fruit - flower taste and aroma), in a clear roast.
GC, Bezzera Strega, Macap 4M, Graef ES90, Lido, Mokas, Drip, AP & Co.
 
Barrie
I have yet to be impressed with the usefulness of a drying phase with my setup, environment and beans. I recently gave it another shot. The first run of 227gm SM Moka Kadir taken to Vienna/Vienna+, used my more routine profile, which is preheat/beans in/482 to 1C/440 to end. Next I used Eddie Dove's basic profile which included a drying phase, slow rise, and no decrease after 1C. We drink espresso and my wife's immediate comment after drinking the ED profile was that the coffee tasted "bitter." I felt it had lost much of its maltiness and chocolate taste. Baked beans?
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
Barrie
There is an interesting discussion going on in the Roasting Coffee section regarding the drying phase (IP: 67.166.10.193) and I am now wondering whether much that is handed down from the experts stems from the need to slow down professional level roasters with "super heaters" in the early phases, and this does not translate well to the GC with its less powerful heater and slower early temperature rise.
For example, if I do a control run and put 227 gm beans in the GC with no preheat and the set point at 482, it reaches 400 with amber beans in about 12 minutes, going from pale to yellow to amber during the previous minute. I get to 460 and first crack at about 12 minutes. Has it not gone through a drying phase in the first five minutes? Are the beans likely to be inadequately dried in the center? Exactly what is added by preheating and a targeted drying phase?
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
allenb

Quote

Barrie wrote:

There is an interesting discussion going on in the Roasting Coffee section regarding the drying phase (IP: 67.166.10.193) and I am now wondering whether much that is handed down from the experts stems from the need to slow down professional level roasters with "super heaters" in the early phases, and this does not translate well to the GC with its less powerful heater and slower early temperature rise.
For example, if I do a control run and put 227 gm beans in the GC with no preheat and the set point at 482, it reaches 400 with amber beans in about 12 minutes, going from pale to yellow to amber during the previous minute. I get to 460 and first crack at about 12 minutes. Has it not gone through a drying phase in the first five minutes? Are the beans likely to be inadequately dried in the center? Exactly what is added by preheating and a targeted drying phase?


Most commercial and semi-commercial roasters have at least a small amount of power headroom if not more. Every roaster I've ever built has had quite a bit of headroom but mostly resulting from over-design due to a fear of getting through the build and not being able to get the job done.

Consumer non-convection type drum roasters as with the Hottop seem to be designed with little headroom and convection type (Gene) capable of 1/2 lb batches are necessarily limited in headroom due to the limitations of 120 V household circuits.

If any roaster spends 11 + minutes getting to yellow or even amber assuming it didn't take 9 minutes getting to 250 F it will be very dry and there will be no need for trying to create a drying phase.

I'm curious that some seem to have much more available power with their Gene than others. I've read posts from some Gene users reporting the ability to hit yellow in 6 min or less and others cannot. I wonder why the variations with the same roaster?

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb

Quote

Barrie wrote:


For example, if I do a control run and put 227 gm beans in the GC with no preheat and the set point at 482, it reaches 400 with amber beans in about 12 minutes, going from pale to yellow to amber during the previous minute.


I've been rereading previous posts on the Gene trying to see examples of speed to yellow and onward. After reading your post again I've got a question.

Are you saying that with a setpoint of 482 F, at the 12 minute mark your Gene is only sending 400 F into the roast chamber?

If this is the case then there is something wrong with your Gene's ability to heat. Or, is this normal for other GC's?

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
troposcuba
Allen, I think you would have to play with a GC to fully grasp how it acts. If you set it to 482, it does not jump directly to that temp. The heating element may be running full power, but it is not enough to instantly jump to the setpoint. I think they actually worked it out pretty well in the engineering of the machine to account for the thermal mass of the drum and coffee etc. If you just set it to max and let it run, then cool when it reaches the desired roast, for the most part you will not have scorched beans. I don't think this is the way to acheive the best results from the machine however.

And to answer your question, I think that this is going to be a similar reaction from any GC, but they may reach the set temp at varying times, and I do not think there is anything wrong with the unit in question. it does seem to be the normal mode of operation.
Sean
 
allenb
Thanks Sean,

I guess I'm too used to seeing any convection heater whether it be a tubular or nichrome be able to climb to a setpoint within a few seconds and even with the tubular which is slower to react, no more than a minute or so.

I wonder if the Gene has something else going on control wise other than the cycling relay that allows a gradual rise in discharge temp?

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Barrie

Quote

allenb wrote:

Quote

Barrie wrote:


For example, if I do a control run and put 227 gm beans in the GC with no preheat and the set point at 482, it reaches 400 with amber beans in about 12 minutes, going from pale to yellow to amber during the previous minute.


I've been rereading previous posts on the Gene trying to see examples of speed to yellow and onward. After reading your post again I've got a question.

Are you saying that with a setpoint of 482 F, at the 12 minute mark your Gene is only sending 400 F into the roast chamber?

If this is the case then there is something wrong with your Gene's ability to heat. Or, is this normal for other GC's?

Allen


I think you already have an answer, Allen. To better understand the GC, you might be interested in looking at Eddie Dove's instructions as to how to get inside it, complete with photographs and annotations.

https://docs.google.com/presentation/d/1SXVoYgJjz8qSS-2y1-K966At92XK_CYD7UA34JddvUs/edit?pli=1#slide=id.i0

There, you will see that there is a cast metal "Heater/fan assembly" through which the air passes en route to the rotating bean container. In that container, a metal plate and the plexiglass become very hot and the beans are tumbled in hot air as the drum rotates around its excentric axis. The temperature sensor is at the far end of the metal-assembly path and so, during a roast set to max and starting with a cold GC, the assembly has to come up to heat. as well as the beans. That process accounts for the delay. With my machine, if I preheat to 350, stop to drop beans in, and restart with the setpoint at 482, the temp readings are (for example) 1min: 340/2min: 375/3min: 390/4min: 412/5min: 435. This all depends on how long I take to put in the beans with the unit stopped, mass and type of beans, as you might guess. The temperatures are higher than BMT, of course.
The point is that, even with preheat and max setting one is not hitting amber until 3-4 min (I think the heater is either on or off and nothing in between but I am not sure). It might be a good idea to hold at 400, which is amber point, or a little below until 5 min? Trial and error with specific beans is the answer of course, but what is your gut feeling?
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
Barrie
Allen, I misstated the times from a cold start. From the record of one roast I just looked at, 400 at 7 min and 1C/460 at about 12:30. The time to amber is different but the general idea is the same.
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
allenb
Thanks Barrie, I think I'm finally gaining understanding of the GC with the very detailed responses you and Sean have provided. I also looked over Eddie's how to you linked to.

As you noted, the heating element assembly appears to have been designed to have a natural, paced rate of rise. I'd like to find a photo of the heater internals some day.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
ML
My GC is on its way from SM's and should arrive later this week.
I have figured out how to handle any smoke issues by clearing a large swath of desk space, which sits right in front of the one and only window, and placing the GC right underneath the window. I have purchased 8' of 3" aluminum tubing to vent this bad boy right out the window. Cool Breeze Mahn
I think the question of Barrie's interesting threads is "is there is a real need to warm the GC up prior to inserting the beans into the roaster to roast the coffee to GC perfection (whatever that is)"? Roasting coffee in the GC is not like baking a cake or bread in a pre-heated oven. It's utilizing a home roaster with some unique limitations and roasting coffee beans. Will pre-heating the GC dry the beans quicker and better than not pre-heating? Quicker and better meaning the end result being a better roast. Will beans dry from a cold GC in about the same time as a pre-heated GC? And if it takes a bit longer will it affect the end result? Drying too fast with too high a temp is not logical. Just drying from a cold start seems to make some sense to me but then again I don't know what I'm talking about but it was fun saying so. Are experienced GC users pre-heating just because....., or is there a reason physically and/or chemically happening inside the bean to justify this? Anyway, Barrie posited the question and the consensus seems to lean towards pre-heating the GC. I will try both. Am I having fun, yet? y'bet!
 
Barrie

Quote

allenb wrote:

Thanks Barrie, I think I'm finally gaining understanding of the GC with the very detailed responses you and Sean have provided. I also looked over Eddie's how to you linked to.

As you noted, the heating element assembly appears to have been designed to have a natural, paced rate of rise. I'd like to find a photo of the heater internals some day.

Allen


If I come across anything even more detailed I will let you know. Meantime, these are hard to beat for anyone new to or thinking of buying a GC:

http://www.frcndigital.com/coffee/genecafe.html

http://coffeegeek.com/reviews/accessories/genecaferoaster/EddieDove

There is a conflict as to where the authors think the temperature that is displayed is being measured! To me it makes sense that it would be at the air-entry end, but I am looking forward to hearing back from the company.
Edited by Barrie on 02/17/2013 6:14 PM
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
Ryan

Quote

Barrie wrote:

If I come across anything even more detailed I will let you know. Meantime, these are hard to beat for anyone new to or thinking of buying a GC:

http://www.frcndigital.com/coffee/genecafe.html

http://coffeegeek.com/reviews/accessories/genecaferoaster/EddieDove

There is a conflict as to where the authors think the temperature that is displayed is being measured! To me it makes sense that it would be at the air-entry end, but I am looking forward to hearing back from the company.


Well, to throw in another possibility, I was under the impression that the temperature readout was actually some sort of average calculation between the two sensors.

ML, I think that preheating the roaster has a few benefits. Having the roaster preheated to a set level every time helps with consistency for one. Also, it seems to help the roasting process get moving along a little more quickly without subjecting the beans to anything that's going to hurt them. That's what I've found at least, maybe more experienced roasters know of other benefits.
 
hazbean
Been away from forums etc for a few weeks, come back to see quite a bit of activity on the Gene front!

I'm not using my Gene a lot at the moment, but I did look into these things a fair bit during the four years or so that I was using it all the time.

Re the temp readout. I'm pretty confident that this number is primarily derived from the left hand (exit ) end sensor. These are my reasons for thinking that:

1. I drilled holes and put a K-type TC probe at the same position. The readings from that tracked almost exactly the GC's probe in the roasting temp range.

2. The GC information repository at coffeetime.wikidot.com reports a similar conclusion see eg http://coffeetime.wikidot.com/inside-a-gene-cafe. This wiki is a very useful resource for GC information.

3. I measured the air temp (as it enters the roast chamber) at the right hand end at 320C.

4. Once I inadvertently roasted 300g of very chaffy beans. Chaff built up on the collector to the point where the wiper couldn't get rid of it and the airflow blocked. The temp readout plummeted, but power didn't -- it was obvious that the BMT was rising, very nearly to the point of ignition. Clearly the temp readout fell because the flow of hot air over the sensor was restricted.

The GC control system (embedded in its PIC microcontroller) uses the right hand (heater) end sensor for error conditions, and also to cycle the heater in certain situations, probably related to the difference between the two sensors. A friend and I have spent ages trying to figure out exactly how this works, but it is not obvious. The answer would be in the PIC code, but the controller has (unsurprisingly) been nobbled to prevent reading the code out.


Re drying cycle and preheating. For a long time I used a specific drying phase, but was often frustrated that it slowed the roast and I couldn't do faster profiles when I wanted to. I concluded that the GC was actually heat limited, and the best way to treat it was to get as much heat as possible into the roasting environment as soon as possible. Consequently, my basic technique is to set it to max (250/482), preheat until max is reached, then add the beans and continue to run at max until around 1C, then drop back to some empirically determined point (usually in the 238 to 242C range) that allows the roast to get to a bit before 2C in about four minutes. I was happy with the results from this, and ended up using it most of the time. This technique sees yellow reached at around 4:30, which is the desired outcome of drying anyway -- so the drying phase is essentially implicit in the profile.
 
ML
hazbean - I loved the fact that you drilled holes in your new roaster!
Ryan - Thanks for the help, buddy

As far as pre-heating goes: isn't starting from cold having the GC temp consistent?
let's pretend -
depending on where you're at room temp beans are anywhere from 40* to 85* (we're pretending, you see)
you place the beans in a warmed-up Estopped GC
once you've restarted the internal drum temp is different for each user because of a few factors but we can all agree it's warmer than cold in there
you set the controls for a warming phase let's say 300* for 5 mins
whatever the BMT is after that 5 min yellowing interval no one knows but the beans are whatever temp they are and you begin your roasting profile and you're satisfied, more than satisfied with the resultant roast
If you begin at cold and set the controls to 300* for 5 mins you might find the beans are indeed yellow at this point, perhaps less time spent at yellow but just as yellow as the bean can be, cowardly bean, you begin you're profile and are/are not happy with the resultant roast
reaching yellow beans at about more or less 5 mins in a pre-heating drying phase seems to be the sweet spot for the GC roaster,
anyone's everyone's GC roaster?
and there seems to be many ways to get there depending on the home roaster

There are many ways to skin the bean with this here machine and find that shiny glean on the surface of that there bean and grind the results into a savory grin but don't spill a drop because it's the last of that there crop...
 
Steve Egge
This was my "experiment" weekend.
I bought some beans from SM - the "Panama dry process gone awry" cheap beans and used them to test out some stuff.

All roasting stopped by E stop .. shaking the beans to the left side ... standing the drum on the drum holder, opening the lid, and inserting a thermapen into the bean mass and "stirring" in a figure of 8 fashion, recording the maximum bean temp. No beans were used twice. (I prevented damage to the Gene by inserting another roaster drum and hitting cooling phase).

All were done with preheated drum to 400?F with 227 grams of beans ...

Warm Beans at 350?F x 4 Minutes ... BT 238?F wt 222.1 gm = 2.16% wt loss
Warm Beans at 350?F x 5 Minutes ... BT 254?F wt 220.9 gm = 2.69% wt loss

So during this "drying phase" if you will ... heat is still being applied to the beans and the temps are rising ... although slowly throughout this phase ... that is they are not totally stalled (although not heating up as fast as if you were at 482!)

This reflects my experience with a bean I was having trouble with ...
I previously roasted Guatemala Huehuetenango Finca Rosma with a 4 minute drying period trying for a lighter roast and found it had a bold lemon flavor .. like it was under roasted.
So I next tried it with the same profile but extended the drying period to 5 minutes at 350 (instead of 4) and despite ending up with less bean wt loss by a percent, that is to say it was a lighter roast, there was less lemon grass flavor ... more of what I would expect it to taste like.
(basic profile stolen from Drew - Army Coffee)
preheat 400
warm beans 350 x 4 minutes
482 till 40 sec into first crack
Then lower to 456 till you stop roast.

BTW I'm pretty happy with the thermapen (a bit pricy but I can use it for other things) and it is quick to temp and seems fairly accurate. Much more responsive time wise than using a thermo probe plugged into a hand meter.

Steve
Santoker Rev 500, Baratza Vario-W, HG-One, Bunn Trifecta MB, AeroPress, Londinium I
 
Barrie
Hazbean, Good to "talk" to you again. This is great information and I can almost foresee what I am going to get from the company - not as much as you are providing.
As for the drying phase elimination, and preheating to 482, that is very interesting and the opposite to what "everyone" else has been saying. However, if you get to yellow in 4:30 that seems about right. I am surprised also that when you drop from 482 to 468 (242C) after 1C it takes you four minutes to get to 2C. Depends on the bean and quantity but the general impression I get is that your setup results in a slower roast than many, including mine. Maybe its all those holes you drilled. Roflmao
I know from my own records that I would get there a lot quicker, but that's what makes a ball game, as the saying goes.
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
Steve Egge
Another temp experiment ... I tried to do this so there was less variability.
In my machine I hit first crack at 460 - 464 readout on the temp ... that Is I think I hear it at 460 .. but not really sure .. notice the start of chaff and buy 464 there is no doubt that first crack is well underway ... so took temp reading 1 minute after hitting 460 (meaning I was still in first crack but not done)

I put on a Kill A Watt on the outlet and my voltage is 120 ... with the Gene on full it pulls it down to 117 and cycles a bit from there to 120 which I think is fairly normal.

227 grams of beans
preheat to 400
dry x 350 x 4 or 5 minutes
482 till 1 minute after reaching 460 degrees - E stop ... shift beans to left side of drum, stand up and insert thermaprobe ...

4 minutes of drying ... hit 460 at 10:30 and got the E stop at 11:45
Bean temp was 388 (first crack started at 10:45 by my ear)
bean wt was 197.7 gm for 12.9% weight loss

5 minutes of drying ... hit 460 at 11:13 and E stop at 12:15
Bean temp was 382
bean wt was 197.4 gm for 13.0% weight loss

Kind of reminded me of chem labs in college ... lots of variables but sure seemed to answer at what temp the beans were at when first crack commensed. I thought the bean temp would be higher on the 5 minute drying .. but it the higher level on the first try might have been due to the extra 15 seconds of time before I could get the drum out.

Just thought I'd share.

Steve
Santoker Rev 500, Baratza Vario-W, HG-One, Bunn Trifecta MB, AeroPress, Londinium I
 
ML
so Steve - you pre-heated your drum to 400*--with 8 oz of beans--did you place the beans in a cold (room temp) drum? then warm the drum to 400* --time elapsed?
or did you pre-heat an empty drum to 400*; elapsed time?, Estop then add the room temp beans?
then 'dry' the beans; better result at 350* for about 5 mins instead of 4 mins
if you added the beans to a cold drum then you dried for x mins @ 400* then continued drying for 5 mins @ 350*
total drying time x+5 mins? too long? sour taste? did you rest the beans for 72 hrs? if not try that

hazbean preheats the drum until max then Estops then adds the beans then roasts at max and yellows at about 4 1/2 mins

my question or observation seems to be that:
The GC dries (yellows) the beans at any temp the drum temp starts at when one adds the beans--- room temp to 482* in about 5 mins
be it inserting the beans at 482* as hazbean and Barrie has observed or 300*-350* as Steve and Ryan and others have found
or inserting the beans at a room temp and setting the temp anywhere from 300* to max (482*) for about 5 mins
that 5 min mark comes up again and again
I'm going to write a song of thanksgiving a hymn of praise a paean to 5 mins
as soon as my GC arrives and I know what it is I'm writing about
 
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