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allenb
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· 04/02/2020 4:50 AM
Morning Ed, I haven't done any green coffee hoarding yet but am hoping the supplies don't end up like the toilet paper isles!

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· 03/31/2020 2:53 PM
Hey Ed. Thanks. roar

homeroaster
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· 03/31/2020 11:21 AM
Hey quarantined home roasters! I hope you have great coffee! If they have a run on coffee, I hope you're set with your great home roast! Find me on Facebook! Ed Needham

snwcmpr
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· 03/25/2020 11:49 AM
New Rochelle in the news. I think of you every time I hear it. ... Please stay safe.

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· 03/21/2020 7:36 AM
Good morning homeroasters morning Everyone is hopefully staying healthy through this. Hang in there and stay safe!

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optimum temperatures for roasting
simagic
best post


If I read 5 different articles on temps, it appears i get 5 different answers. What I'm trying to find out is should I set my Gene to 482 and leave it there....Should I set it to __?__ and turn down to_?___ after the first crack.
Should I start at higher temps ( obviously only up to 482) for higher grown coffee and lower, higher temps for lower grown coffee ( as per one of the articles I've read)........I roast mainly high grown Guatamalan . I just can't get any clear answer as to where to set the temps ( Farenheit please). I've read many of the messages in this forum but it's just touch and go trying to find info on this. Although I'm a brand new member, might I suggest a separate heading for "temps and times" for the popular Gene.. I'm seeing 482 in some messages..In others i see 460, 452, 474..(up down and all around)...etc.etc.etc. Apparently it must make a difference. So I need some help with that and I would be pretty sure others would also like that info as well.
Edited by ginny on 07/17/2012 7:15 PM
 
ciel-007
Hi Simagic, and welcome to HRO.

With the GC, you will find that there’s no direct, simple answer to your question. In my experience, it was largely a matter of trial and error before arriving at the optimal roasting settings. You will first need to test your GC to see how quickly it reaches 482F. Although rare, some GCs are very very fast, and may even lead to scorching as discussed in this thread:
http://homeroasters.org/php/forum/vie...ad_id=2744
The main challenge you face with the GC is that there is no way of knowing the actual temperature of the bean mass during roasting. You will have to learn to judge the BM temperature using other clues like smell, smoke and bean color.
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK�NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
John Despres
Welcome! Thanks for joining!

Good question. It varies all across the board for several reasons. As Ciel says, a good part is experimentation. Type of coffee and grade make a big difference as well. Available voltage is another reason.

Odds are your Guats are graded SHB (strictly hard bean) or SHG (strictly high grown). Both are hard, dense beans.

Try this for starters -

Warm your empty roaster to 300F for a few minutes.

Add the beans and set the temp at 300F with the timer at 30:00

After 5 minutes, raise the temp to 470F and wait for 1st crack, probably around 12 minutes or so, but pay close attention

Wait 30 seconds after 1st crack has started and drop your temp to 445F.

Now it's decision time. City plus roast? Full city roast? Full city plus? I like to pull most of mine about 4 minutes after 1st begins for a full city.

One thing to keep in mind is to always use the exact same amount of coffee. Since it arrives measured out in pounds, I divide mine into half pound lots (or 226 grams). Eliminate this variable by remaining consistent.

This will be a good starting point for you. Feel free to ask as many questions as you like. Everyone here is very patient and willing to help.

As Ciel also mentioned, knowing the rate at which your roaster heats up is a big help. Set your cold, empty roaster at 482F, hit start and time how long it takes to reach 482F. This will give us a reference point in helping as well.

Things to let us know after you finish a roast - your temps, time of first crack, end of roast time and how you cool your beans.

Have fun and good luck!

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.
 
www.sceneitallproductions.com
ginny
one of my jobs is reminding you to use/post an avatar. we will give you one in about 5 days though you may want your own...

ginny

Roflmao
 
ciel-007

Quote

John Despres wrote:

Wait 30 seconds after 1st crack has started and drop your temp to 445F. Now it's decision time. City plus roast? Full city roast? Full city plus? I like to pull most of mine about 4 minutes after 1st begins for a full city.



John, with the above parameters are you not encouraging the beans to enter second crack before dumping? If we assume that first crack begins around 383F, and that exothermic reactions cause the bean mass temperature rise to accelerate, shouldn’t we expect the above time and temperature settings would push the bean mass beyond the 428F threshhold into second crack?
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK�NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
John Despres
Ciel, on the surface your observations seem correct.

The Sweet Maria's roast reaction chart says first starts at 401F and second at 454F.

Setting the Gene Cafe at 445 is more realistically a setting of 440-442F or so as the temp swings up and down once 445F is reached. Reaching second is very unlikely - or at least I haven't done it. Try this - set your GC at 445F and see how long it takes to reach 2nd crack. Don't stop the roast let it go.

This is a profile I use for Guats like Simagic is roasting.

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.
 
www.sceneitallproductions.com
coffeeroastersclub
I shoot for 454 degrees F at 11:50 for a Full City+ for my single origin roasts. Its from the sweet marias chart (which John referenced) which is very informative. I find that full city+ is good for espresso.

Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
 
http://www.coffeeroastersclub.com
ciel-007

Quote

John Despres wrote:


The Sweet Maria's roast reaction chart says first starts at 401F and second at 454F.



When I first started roasting, I read several SM articles on this subject, and they were a source of confusion for me. As I went through the SM site, I found important contradictions in the numbers for first and second crack. More importantly, I don’t recall seeing explanations about how these temperatures were actually measured.

On the subject of first crack for example, at one point SM says “First Crack Begins: 355 degrees f. internal bean temperature”; however, in another part of the site, SM says that first crack begins at 401F. Given the critical importance of temperature on roasting results, I am now monitoring the bean mass temperatures at which first crack occurs for each roast. Based on the observations obtained with an Omega thermocouple, I know that first crack typically occurs when the bean mass temperature is 383F; that’s well above 355F, and below 401F. It’s my impression that SM’s temperatures regarding first crack are approximations.

On the subject of second crack for example, at one point SM says “ 415-425 degrees f. internal bean temperature… where the coffee has just barely showed signs of 2nd crack…”; however, in another part of the site, SM says that “ The internal bean temperature for second crack normally is 446 degrees farenheit.” Based on the observations obtained with my Omega thermocouple heat probe, I would agree completely with SM when it says that at 425F the coffee is showing signs of second crack. However, in my opinion, implying that second crack occurs at 446F is incorrect.

You may be surprised to learn that there is a lot of contradictory information across the WWW about the actual temperatures at which coffee cracks. One of the reasons for this may lie in the fact that there is no established way of precisely measuring actual temperature during the complex cracking process; further, few sites take the time to explain exactly how the temperature was actually measured. In some cases, what is being reported is simply the temperature of the roasting chamber at the time when the crack is heard. However, I have found several sites on the web that report actual bean mass cracking temperatures that closely correspond to those I have measured with my Omega thermocouple.
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK�NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
John Despres
Hmmm, Interesting. Yours is the first notes I've seen of first crack taking place well outside of the norm practiced rather broadly.

I never noticed any inconsistencies in Thom's information. I'll go back and look again. Perhaps you can provide links to his errors? That would help me and I'll contact Thom about it, too so he can tighten up his info.

It's my opinion Thom Owen is much smarter than I am, has considerably more experience, owns much better gear than I do, and is much more involved in roasting than I am. I trust Thom and have seen matching numbers used by Willem Boot, Kenneth Davids and further supported by William Ukers, author of "All About Coffee", the coffee Bible. These folk are who I recognize as the great roasters of the 20th century.

As you know, I have no way of placing a gauge of any sort in my roaster, so I must rely on the vast bodies of work by others. These numbers are the markers I would use to correctly place a probe in the bean mass if I were to do so. I could probably place one in a location that says 1st occurs at 480F, but I'd be mistaken.

A search produced no sites saying 1st occurs very far afield from 400F, further out than 5 degrees either way.

Here is another of my sources.

http://www.coffeeresearch.org/coffee/...asting.htm

Now, I'm willing to change everything I know, but I need a large amount of support for my new way of thinking, so any provided links as well as books will be a great help. Thanks!

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.
 
www.sceneitallproductions.com
coffeeroastersclub

Quote

John Despres wrote:

Hmmm, Interesting. Yours is the first notes I've seen of first crack taking place well outside of the norm practiced rather broadly.

I never noticed any inconsistencies in Thom's information. I'll go back and look again. Perhaps you can provide links to his errors? That would help me and I'll contact Thom about it, too so he can tighten up his info.

It's my opinion Thom Owen is much smarter than I am, has considerably more experience, owns much better gear than I do, and is much more involved in roasting than I am. I trust Thom and have seen matching numbers used by Willem Boot, Kenneth Davids and further supported by William Ukers, author of "All About Coffee", the coffee Bible. These folk are who I recognize as the great roasters of the 20th century.

As you know, I have no way of placing a gauge of any sort in my roaster, so I must rely on the vast bodies of work by others. These numbers are the markers I would use to correctly place a probe in the bean mass if I were to do so. I could probably place one in a location that says 1st occurs at 480F, but I'd be mistaken.

A search produced no sites saying 1st occurs very far afield from 400F, further out than 5 degrees either way.

Here is another of my sources.

http://www.coffeeresearch.org/coffee/...asting.htm

Now, I'm willing to change everything I know, but I need a large amount of support for my new way of thinking, so any provided links as well as books will be a great help. Thanks!

John


John, I believe I saw some notes on how altitude can affect the roasting temperature guidelines; something along the lines of if you are high in altitude you need to adjust your roasting temps approx 20 degrees lower. So if I am shooting for 454 F for a full city+ (according to SM guidelines) I need to really shoot for 434 F. I guess what I am getting at is how high is Ceil above sea level?

Ceil, can you add on to this?

Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
 
http://www.coffeeroastersclub.com
John Despres
Aha! Good point, Len! And there may lay the difference. Curious to know.

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.
 
www.sceneitallproductions.com
John Despres
Well.

I've now spent more time carefully combing through Thom's site.

Holy smokes, first crack does indeed seem to take place somewhere between 390F and 410F. Second appears to be a little tighter, occurring between 440F and 454F. In either case those are some wide spreads.

These numbers appear to put Sweet Maria's in a minority in my collection of trusted resources. Hmmm.

Ima head over to the Sweet Maria's forum to see if it's answered.

Good heads up, Ciel!

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.
 
www.sceneitallproductions.com
ciel-007

Quote

coffeeroastersclub wrote:

I believe I saw some notes on how altitude can affect the roasting temperature guidelines; something along the lines of if you are high in altitude you need to adjust your roasting temps approx 20 degrees lower...


Len, you are correct. We know that water boils at 212F at sea level, but that it boils at a lower temperature at high altitudes. The same thing applies to coffee roasting. Here’s an interesting commentary about the benefits of high altitude roasting by Ryan Knox:
http://best-home-espresso-machine.inf...fee-online
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK�NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
ciel-007

Quote

John Despres wrote:

Holy smokes, first crack does indeed seem to take place somewhere between 390F and 410F. Second appears to be a little tighter, occurring between 440F and 454F. In either case those are some wide spreads.


John, I assume that the variances about the temperatures at which beans crack on the SM site are merely a function of the different methods used to meassure temperature by the various contributors. I think we would both agree that some methods yield more precise measurements than others, and it is those precise measurements that we would both like to see. The critical question I was asking is: “what is the actual temperature inside the coffee bean” when first crack begins, and when second crack begins? As a newbie, I felt it was important to get a solid answer to that fundamental question before attempting any profiles on my home roaster. When I saw how poorly SM had addressed this basic question, I quickly turned to other sources.

John, as far as I can tell, the numbers you are quoting from SM still seem to be higher than they should be. I don’t think that those numbers accurately answer the question “what is the actual temperature inside the coffee bean” when first crack begins, and when second crack begins? John, you’re the real expert when it come to coffee, and have read many books on the subject. Earlier, you cited some authors; would it be possible for you to point me to some sources that might provide specific details about how these authors actually measured the temperature inside the coffee beans at first and second cracks?
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK�NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
John Despres
No one knows what the actual temperature inside the bean is. Bean mass measurement is the only way to come close.

I'll see what I can find, but I think I'll say now I'll disappoint you. I'm not sure anybody outside of our community here discusses in depth how temps are arrived at. I assume they are using probes built into their commercial roasters (Probat, Deidrich, USRC and so on...) or sampler roasters.

As to the mechanics, I don't think I've seen anything anywhere. They all speak of the temps, but not the mechanics...

Anecdotal evidence with two commercial roaster friends shows first at between 398 and 402F. One of them doesn't go to second and I don't think I've discussed 2nd crack with the other.

Good probing question. I'll go on a hunt and see what I find. Anybody else got anything to help out Ciel? Exactly how do they measure temps in the drum?

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.
 
www.sceneitallproductions.com
coffeeroastersclub

Quote

John Despres wrote:

No one knows what the actual temperature inside the bean is. Bean mass measurement is the only way to come close.

I'll see what I can find, but I think I'll say now I'll disappoint you. I'm not sure anybody outside of our community here discusses in depth how temps are arrived at. I assume they are using probes built into their commercial roasters (Probat, Deidrich, USRC and so on...) or sampler roasters.

As to the mechanics, I don't think I've seen anything anywhere. They all speak of the temps, but not the mechanics...

Anecdotal evidence with two commercial roaster friends shows first at between 398 and 402F. One of them doesn't go to second and I don't think I've discussed 2nd crack with the other.

Good probing question. I'll go on a hunt and see what I find. Anybody else got anything to help out Ciel? Exactly how do they measure temps in the drum?

John


John, I don't know if this is putting the cart before the horse, but I am just a bit above sea level and I shoot for 11:50 @ 454F and I always get Full City+. Right on the money. So if someone is much higher in altitude maybe they can do the temp adjustment and get Full City+ (or any other roast) time and time again using Toms guidelines?

Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
 
http://www.coffeeroastersclub.com
hazbean
On the subject of actual internal bean temperature.

I suspect there is very little hard information on this is because it is difficult to measure, and the measurements are I suspect published in technical work that is often proprietary.

Some time ago I found this document which, while it doesn't directly answer the question, offers a lot of insight into the problem (interesting apparatus described on p33).

See http://e-collection.library.ethz.ch/v.../eth:23461

There is a lot of fascinating information in here on many aspects of roasting but it's a highly technical document hence hard going to extract it ...
 
John Despres

Quote

coffeeroastersclub wrote:

John, I don't know if this is putting the cart before the horse, but I am just a bit above sea level and I shoot for 11:50 @ 454F and I always get Full City+. Right on the money. So if someone is much higher in altitude maybe they can do the temp adjustment and get Full City+ (or any other roast) time and time again using Toms guidelines?

Len

Len, Great idea. I hope we have a high altitude roaster who can share their experiences and data.

Anybody?

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.
 
www.sceneitallproductions.com
troposcuba
my house is at about 3200' in Tucson. Not exactly high altitude, but not sea level either, I also have very very low humidity for most of the year (although that is not true lately with our monsoon season in full swing). I roast mostly on my GC, but also have available my old iRoast2. Let me know the parameters of any experimentation you would like me to do and I will see what answers I can provide. I do know that water boils right at 106* according to the wife's candy thermometer. Now you have me wondering if the gage on my La Pavoni is "gage pressure" or "absolute pressure" (I am a diving instructor, so that is where that thought comes from).
Sean
 
ciel-007

Quote

John Despres wrote:

I've now spent more time carefully combing through Thom's site. Holy smokes, first crack does indeed seem to take place somewhere between 390F and 410F. Second appears to be a little tighter, occurring between 440F and 454F. In either case those are some wide spreads. These numbers appear to put Sweet Maria's in a minority in my collection of trusted resources. Hmmm. Good heads up, Ciel!


John, I ran across an interesting quote from Neal Wilson (RoastersGuild, WilsonsCoffee) which would seem to further discredit some of the high coffee cracking temperatures being reported on some popular sites. Here is what he has to say on this topic:

“First and second cracks should be at about the same temperature pretty much regardless of what's going on in the way of a profile… My numbers for the temperature at easily observed points (green to yellow at 300, yellow to brown at 330, First Crack at 380, Second Crack at 430) match up well with values obtained from an experiment… that measured bean temperature by embedding tiny thermocouples inside some coffee beans… That said, getting a probe placement that reproduces those values isn't always easy… with numbers that far off of expected values my first guess would be that you're not getting a bean temperature measurement.
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK�NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101
 
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