The GC excels among its peers by providing complete manual control of the roasting process with its precision time and temperature dials. However, many new GC owners experience a common challenge during their early roasts: they spend a lot of time, and may possibly waste a lot of coffee, trying to develop a “feel” for the time it takes for the roasting beans to absorb the heat inside the pyrex drum. Examples of this challenge may be seen in threads dealing with “Optimum Temperatures”, “Uneven Roast”, and “Scorching”, among others…
The above challenges are due in part to the fact that the GC does not have a Bean Mass Temperature (BMT) probe inside its drum. In order to address these challenges, some GC owners have tried using roasting profiles developed by other GC owners. Alas, sharing roasting profiles does not always work because each GC roaster has slightly different heating characteristics; further, each GC will roast in its own peculiar way because of the influence of many unique environmental variables (wide ranging ambient temperatures, altitudes, line voltages, coffee types, bean masses, etc…)
However, there is a way of addressing some of the challenges identified above. It involves learning how to reveal the BMT inside your GC, without the need for a BMT probe. This is a manual procedure; it relies in part on information posted here at HRO, and in part on information provided by your GC roaster.
Edited by allenb on 08/01/2012 19:28
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
Information Required To Reveal Bean Mass Temperatures in your GC
The following information will allow you to reveal the BMT in your GC, with surprising accuracy, during the most critical moments of the roast. It involves combining information from two sources, followed by a bit of analysis.
First, you must know the temperature at which First Crack (FC) begins. That information has been posted at HRO: As a general rule First Crack begins at 384F http://www.homero...post_38081
You must also know the temperature at which Second Crack (SC) begins: As a general rule Second Crack begins at 428F http://www.homero...post_38082
Second, you need information that is provided by your GC roaster. Namely, the temperature inside the roasting chamber (see GC display), the roasting time elapsed (see GC display), and the sound emanating from the roasting beans (listen to GC exhaust). Learning how to recognize the subtle cracking sounds cloaked in the noise of the exhaust, may present a challenge for some owners: http://homeroaste...ad_id=2714
I was able to overcome this issue by using a stethoscope.
Third, you will need a notepad to record your observations, and to conduct a brief analysis of the results. Also, having a stopwatch may facilitate monitoring the elapsed time between FC and SC during several roasting trials.
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
It is now a matter of conducting several trial roasts with your GC, to record a few observations on a notepad, and to draw some conclusions. For this, I suggest using a simple 2 stage roasting profile. The objective of the trial roasts is to find an acceptable initial GC temperature setting to achieve FC relatively quickly (say in about 11 minutes), and then to find the best follow-up GC temperature setting to achieve SC in 4 minutes. This typically involves setting the GC to 482F to reach FC quickly; then reducing the GC temperature, as soon as FC begins, in order to slow down the rapid heat rise inside the beans, and to stretch the roasting time to 4 minutes before SC begins. For consistency, each roasting trial must use the same quantity of coffee, and beans that originate from the same location. Repeated roasts will be required in order to find out, through trial and error, the best follow-up temperature setting to achieve a 4 minute roasting period before the onset of SC. The reason for choosing a 4 minute window between FC and SC is that it provides sufficient time for complex chemical reactions to develop, and to impart those wonderful flavors and aromas that coffee lovers enjoy.
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
Examples of the Trials Required to Reveal BMT in your GC
Here, I show examples of 3 typical trials to illustrate how you might go about implementing the above steps. It is likely that you may require more than 3 trials to find the correct follow-up temperature required during the second roasting stage.
Trial #1 - Times to First Crack and Second Crack (GC at Full Power):
Step 1-Measure 226 grams of beans, preheat GC to 300F
Step 2-Set GC to 30 minutes and 482F; drop beans, start roasting, start Stopwatch.
Step 3-When First Crack begins, write down the Stopwatch time and the BMT as 384F.
Step 4-Leave GC temperature at 482F, and allow roast to proceed to Second Crack.
Step 5- When SC begins, write down the Stopwatch time and the BMT as 428F.
Step 6-Dump the roast, analyze results, then proceed to the next trial…
Analysis: In your notebook, record the amount of time elapsed between First Crack and Second Crack. The time for this early trial should me much less than 4 minutes. Hence, you will need to conduct a few additional trials with the objective of increasing the roasting time between FC and SC to 4 minutes.
Trial #2 Times to First Crack and Second Crack (GC at Reduced Power):
Steps 1-3 Same as above…
Step 4-Reduce the temperature to 452F (for example), allow the GC to proceed to SC.
Step 5- When SC begins, write down the Stopwatch time, and the BMT as 428F.
Step 6-Dump the roast, analyze results, and proceed to the next trial, if needed.
Analysis: In your notebook, record the amount of time elapsed between FC and SC. You will likely still be short of the 4 minute goal at this stage. If so, proceed to trial #3 using an even lower target temperature in Step #4.
Trial #3 Times to First Crack and Second Crack (GC at Reduced Power):
Steps 1-3 Same as above…
Step 4- Reduce the temperature to 432F (for example), allow the GC to proceed to SC.
Step 6- When SC begins, write down the Stopwatch time, and the BMT as 428F.
Step 7-Dump the roast and analyze the results. Run additional trials if needed.
Analysis: In your notebook, record the amount of time elapsed between FC and SC. If it shows 4 minutes you have reached your target and can stop the trials. If it still shows less than 4 minutes, you will need to conduct a fourth trial using an even lower target temperature in Step 4.
( If it shows more than 4 minutes, conduct a fourth trial using a slightly higher temperature in Step 4. Further, you may need to repeat the above steps beyond a fourth or fifth trial in order to fine tune the temperature on the GC and to achieve the targeted 4 minute delay between FC and SC.)
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
How to Analyze your Trial Results to Reveal BMT:
(this example uses ideal stopwatch values; the minutes in your trials will differ)
Example of summary observations from GC trials:
-FC began when the Stopwatch showed 11 minutes, and GC was set to 482F.
-SC began when the Stopwatch showed 15 minutes, and GC was set to 442F.
Example of Analysis of the above summary observations:
-The time elapsed between FC and SC was 4 minutes.
-BMT was 384F after 11 minutes of roasting (known temperature at which FC begins)
-BMT was 428F after 15 minutes of roasting (known temperature at which SC begins)
-BMT rose 44F during the 4 minute period (between 11-15 minutes of roasting time)
-BMT rose an average of 11F per minute (between 11 and 15 minutes of roasting time)
Example of Revealed BMT values:
-BMT is 384F after 11 minutes of roasting
-BMT revealed to be 395F after 12 minutes of roasting
-BMT revealed to be 406F after 13 minutes of roasting
-BMT revealed to be 417F after 14 minutes of roasting
-BMT is 428F after 15 minutes of roasting
-BMT revealed to be 439F after 16 minutes of roasting
(these are ideal results; the BMTs revealed in your GC may be different)
As you can see, analyzing data from a few trial roasts can provide a lot of valuable insights about the BMT of the coffee inside your own particular GC roaster. Once you have revealed the BMT of your favorite beans, you may place a copy of the results next to the GC. The next time you roast, you may simply keep an eye on the GC timer; by glancing at elapsed times, you will know with accuracy the BMT, and how far the roast has progressed. Based on the above example, you might elect to end the roast after 12 minutes for drip coffee; or perhaps after 14.5 minutes (just before SC to preserve varietal character) for espresso. Further, having reliable BMT information at your fingertips has freed you from struggling to hear the soft cracking sounds hiding behind the noise in the GC exhaust.
This procedure should help new GC owners become more confident while discovering the full potential of this wonderful roaster. As a general rule, I have experienced some fine tasting espressos pulled from beans roasted with a rapid rise to first crack (say 10-12 minutes), followed by a slow ascent to second crack (4 minutes). Mastering this simple two stage profile in the early stages of roasting with the GC should help shorten the steep learning curve that we must all navigate… before moving on to experiment with more elaborate profiles.
Enjoy your Gene Cafe!
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
I was breezing thru this very informative thread. Certainly it requires to be read and re-read as it is indeed detailed and very helpful. One questions that immediately pops into my head was where I read ""Trial #3 .........
Step 4- Reduce the temperature to 432F (for example), allow the GC to proceed to SC.."""
I am not at all challenging that info, but upon reading somewhere else on a different thread on this forum, It was mentioned to.......""lower temp to 445, but might not reach 2c at 445 so might need to raise to 454"" ( or it said something like that).......... That left me with the impression that under 454 (readout on the GC), the beans would not ever reach 2c. This makes me think that if "some certain temp" is not reached that the beans would never reach 2c. Kinda like water temp. You can heat it at 210 all day but won't boil till 212. So, i guess I'm kind of asking, will 2c be eventually reached or does it require a certain temp (on the readout of the GC), as in my boiling water example. .Thanks
Dennis, you raise an interesting question. If I recall correctly, the post that mentioned those high temperatures (445F and 454F), also suggested that SC occurred at 451F. Since then, a HRO member has posted empirical evidence demonstrating that coffee begins SC at a much lower temperature (428F).
Since each roaster is different, I can’t speak to the accuracy of the temperature displayed on every GC roaster. The above experimental method is “ hit and miss “; yet it should enable owners to discover what works on their own, unique, GC roaster. I would expect that some GC roasters set to 432F would eventually reach SC. However, I can’t say how long that might take. Should your particular GC not reach SC within 4 minutes, then you would have to conduct yet another trial, where the temperature in Step #4 is further raised in order to shorten the roasting time. Ciel
Edited by John Despres on 09/24/2012 16:09
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
Ok. Soooooo, If ( for example), I've reached first crack. Now i turn it down to 446 to extend my roast til 2c or just before 2c..( 4 minutes max). Well, the GC will then reach 446, I'll hear the little click, then it will drop down a few (maybe 5) degrees, then work back up to 446, drop down again...on and on.... Aren't I stalling my roast by not allowing it to continue to climb. I was thinking (maybe), that when it hit 446 and then "clicked" and dropped down, that I'd raise temp to 450.( up 4 degrees). Then when it reached 450, clicked and dropped down again (maybe 5 degrees), I'd raise it to 454 (up 4 degrees) and so on. This way the temp was always climbing and "maybe" not stalling the roast. I figure I'd do this until either 2c or it looked dark enough for me and trying not do do that more than 4 min. ( because i read here somewhere not to extend longer than 4 minutes (?). I was just lowering to 446 after 1c and waiting til dark enough for me. Isn't this bouncing up and down between 446 and (lets say) 440 (after the click), just stalling????? dennis
ANNNNND...One more question that I'm not sure about. If beans NEVER enter into second crack, can they still develop oil on them???........dennis
Good question. I have never seen it happen. I believe that since the cell walls have not broken down (a process of 2nd crack) the oils cannot escape to get to the surface of the bean.
Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
ANNNNND...One more question that I'm not sure about. If beans NEVER enter into second crack, can they still develop oil on them???........dennis
Good question. I have never seen it happen. I believe that since the cell walls have not broken down (a process of 2nd crack) the oils cannot escape to get to the surface of the bean.
Len
So, If what you say is true ( and i don't doubt it), then if 4-5 days after i have roasted and i see some oil, then that should be telling me that i actually went to 2c and maybe I didn't even know it. So if i was keeping my log for time and thought it didn't go to 2c, but see oil, then certainly I'll need to shorten the time a bit because I just didn't hear 2c....."but the truth is in the pudding" (whatever that means)
... Aren't I stalling my roast by not allowing it to continue to climb...
Dennis, when you reach 1C (beans are at 384F), and then you decide to turn down the temperature from 482F to 446F, your roast will definitely not stall for two reasons:
(1) Even after the the temperature of the roasting chamber has gone down to 446F, it is still 62F higher than the bean mass temperature was at 1C; and
(2) when 1C begins, the bean mass becomes exothermic (the beans actually generate heat), thus causing a further rise in temperature.
Ciel
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
simagic wrote:
... then if 4-5 days after i have roasted and i see some oil, then that should be telling me that i actually went to 2c and maybe I didn't even know it...
Dennis, if some beans are showing oil, it is likely that they have encountered 2C (which begins at 428F).
When you drop the temperature to 446F for 4 minutes minutes, there is a good chance that the beans will crack a second time. Should that be the case, you might consider lowering the temperature even further after 1C.
I know from experience that Second Crack is NOT easy to hear on the GC; have you considered using a stethoscope, or some other technique, during the final stages of the roast to confirm that 2C did not occur? Ciel
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
... Aren't I stalling my roast by not allowing it to continue to climb...
Dennis, when you reach 1C (beans are at 384F), and then you decide to turn down the temperature from 482F to 446F, your roast will definitely not stall for two reasons:
(1) Even after the the temperature of the roasting chamber has gone down to 446F, it is still 62F higher than the bean mass temperature was at 1C; and
(2) when 1C begins, the bean mass becomes exothermic (the beans actually generate heat), thus causing a further rise in temperature.
Ciel
That's good news. My "logic" was indicating the temp was lowering, but your explanation trumps my logic . Here comes "MY analogy ( to what you said). If I stick a hot frying pan on my arm, it will begin to burn my cells. If I then remove the burning frying pan from my arm, the skins cells will "continue" to burn even though I've removed the burning source.
Analagous to removing/lowering the heat source to the beans, but they still cook.
"DISCLAIMER"..Do not try this prying pan experiment!!.dennis
simagic wrote:
... then if 4-5 days after i have roasted and i see some oil, then that should be telling me that i actually went to 2c and maybe I didn't even know it...
Dennis, if some beans are showing oil, it is likely that they have encountered 2C (which begins at 428F).
When you drop the temperature to 446F for 4 minutes minutes, there is a good chance that the beans will crack a second time. Should that be the case, you might consider lowering the temperature even further after 1C.
I know from experience that Second Crack is NOT easy to hear on the GC; have you considered using a stethoscope, or some other technique, during the final stages of the roast to confirm that 2C did not occur? Ciel
I'll try dropping below 446. I actually have a stethoscope and just for the hell of it tried it out the other day to hear "1c". I placed it on the "large" chaff collector but didn't hear squat. (isn't that where it should be placed?? It did accomplish bothering my ears with the stethoscopes inserts and had to bend over to place it on the chaff collector bothered my back. The thought of having to do all this to hear the cracks bothered my ''fun level" for roasting. It was quite a bother. dennis
Dennis, placing a stethoscope at the opening of the large chaff collector was essential in enabling me to discover 1C and 2C, and then later establishing the critical linkages between those sounds and the temperatures appearing on the GC display.
Once you have documented those critical linkages for you favourite beans (as described here) http://www.homero...post_38248you would typically not be required to wear the uncomfortable stethoscope.
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
Dennis, placing a stethoscope at the opening of the large chaff collector was essential in enabling me to discover 1C and 2C, and then later establishing the critical linkages between those sounds and the temperatures appearing on the GC display.
Once you have documented those critical linkages for you favourite beans (as described here) http://www.homero...post_38248you would typically not be required to wear the uncomfortable stethoscope.
Dennis, you raise an interesting question. If I recall correctly, the post that mentioned those high temperatures (445F and 454F), also suggested that SC occurred at 451F. Since then, HRO has posted empirical evidence demonstrating that coffee begins SC at a much lower temperature (428F).
Since each roaster is different, I can’t speak to the accuracy of the temperature displayed on every GC roaster. The above experimental method is “ hit and miss “; yet it should enable owners to discover what works on their own, unique, GC roaster. I would expect that some GC roasters set to 432F would eventually reach SC. However, I can’t say how long that might take. Should your particular GC not reach SC within 4 minutes, then you would have to conduct yet another trial, where the temperature in Step #4 is further raised in order to shorten the roasting time. Ciel
HRO has not posted any such empirical evidence. Ciel created the post and posted it to the site. HRO is a site for members to share their own experiences. The opinions and experiences posted here are not necessarily those of the website itself.
John
Respect the bean.
John Despres
Fresh Roast 8, Gene Cafe, JYTT 1k, Quest M3, Mazzer Mini, Technivorm, various size presses and many more brewers.
HRO is a site for members to share their own experiences...
Ooops! Looks like you stumbled upon a typo. John, would you kindly help me edit the omission by adding the word “member” after "HRO" please? Thanks mate.
Ciel... seeking Heaven in a cup with......................................................... EXPOBAR Brewtus II - MAZZER Mini E - MAHLKÖNIG/Baratza Vario - GENE CAFE - HOTTOP KN8828P2 - HotTop KN8828B2
I am a bit surprised by the assumption at the beginning of this thread that 1st and 2nd crack occur at an absolute bean temperature. Can someone more knowledgeable than me confirm this? For which beans? Roasted how? etc.
Barrie
"Just one more tweak and I will have the perfect cup."
Previous equipment: You name it, unitl a Fresh Roast SR500 arrived in March, 2012, then a GC.
Now: Hottop B-2K, Jura Capresso ENA 3 (i.e. espresso).
I can attest to folks being out and about. Me and Julie were out hitting the garden centers for loading flower pots all day. Nice weather! Tomorrow the Kamado/egg gets fired up!
ginny
05/18/2013 17:32
Jack, it is quiet today, I think the lovely day has folks out and about.
ginny
05/18/2013 17:31
sbonder
thanks for joining us...
JackH
05/18/2013 15:28
Quiet here today.
zombie coffee
05/17/2013 11:02
ricksroasters
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allenb
05/15/2013 15:56
nikijack Howdy and Welcome to HRO!
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05/15/2013 13:57
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05/15/2013 03:04
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ginny
05/14/2013 13:54
that is sweet... thanks for posting lylabrown...
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