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Drying Phase Curve
allenb

Quote

Ringo wrote:

I think early on radiant heat is good, with more moisture in the bean the heat soaks deep into the bean. I have cupped coffee dried with higher air in drying and med air and low air, the lower seems better. .


This is an interesting outcome. I've noticed a positive difference with my drum roasts as well when using almost no convection during the first couple of minutes of the roast and gradually bringing the fan up towards the end of the drying phase. I remember a paper done by a Japanese group in the 90's that studied the affects of steam being introduced during the beginning of a roast and they claimed improved results with most coffee's. They had also mentioned a faster initial heat penetration to the core of the bean while steam was present.

Obviously, the steam has to get out of the way fairly soon after the the first minute or so for the coffee to move on to drying.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
snwcmpr
Hmm good topic. I don't start my fan for the first minute, and only run it for 30 seconds 3 times in the first 5 minutes, then it is on all the time. I get to 300 in 4 1/2 (usually) to 5 1/2 (rarely) minutes. The way I read that, I got it right without knowing it.

Love this topic.
Ken in NC
I went to a cupping in SC today
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
Ringo
I think what you are trying to do with the drying is evenly remove most of the moisture in the beans but leave some behind. Dry too fast and the outside of the beans will dry too much and the inside will be too wet. Dry too long and the moisture needed later in the roast is removed. I believe this water is needed for all the chemical reactions we get later in the roast. If we leave the right amount behind and its even all the flavors will develop we love. I do not think any flavors develop until 340 deg bean temp, everything till then is getting the bean ready. 340 deg is were the mallard reactions start and gives the caramel sweetness, after 1st crack we get the complexity and body. All roasters are different and the time too dry will be different. An old time roaster did tell me one day the darker you are going to roast the more moister you want to leave behind in drying.
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
 
Ringo
These are the threads I get on forum for, they make you think!
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
 
jedovaty
Here, check this out:

http://hyperphysi.../spht.html
 
John Despres

Quote

Ringo wrote:

This is what I think, and only think. I am still working on this myself. I believe the more air speed gives gives you more convection heating and less radiant heating. I believe this gives you more heat transfer to the bean with the same temp. I think early on radiant heat is good, with more moisture in the bean the heat soaks deep into the bean. I have cupped coffee dried with higher air in drying and med air and low air, the lower seems better. I preheat my drum to around 260 deg, to store radiant heat them drop in the beans with the air low for the first min. After 1 min I increase the air a little to get the moisture out of the drum. Then I never touch the air setting, controlling the heat is all I can handle. Trying to hit my target times 5 min drying, 5 more min till 1st crack, 2.5 to 3 min after first crack.

If I increase air speed during a roast the Rate of Rise will go up but the quality of the roast goes down. When I built my drum I read a lot of commercial drums are now designed with much higher convection to radiant heat than the older ones, gives a brighter coffee. I read somewhere that the goal was 85 % convection. So I put in big stirring veins to throw the beans in the air and also a lot of air going through the drum. I started roasting on the drum and the coffee from my behmor was better. I started closing the air way down after a min and my coffee was much better, bigger flavor, more complex and better acidity. Its now better then the behmor. This still make no logic to me, but I know it works. So long explanation too say do two roast of the same bean and only change 1 thing, cup the coffee and look for differences. Have friends try it and tell you which is better. My son has a much better plate than me when he comes home we have cuppings, he tells me the better one. Sometimes do three cup, two are the same one is different, can you pick out different one. If you ask me next month how I am drying I may give you a different answer, i keep trying new things cupping the coffee and changing how I roast. One reason I love this hobby it keeps my guessing.

One more thing and I will shut up, the difference between high grown and low grown beans is the density of the bean itself. A kona or a brazilian is like a sponge, less meat for the heat to get through so it heats fast and can burn. A Costa Rican is like a little rock, it loves lots of heat early and needs it to dry.


Very nice stuff here, Ringo. I plan to play with some of this in my Quest M3 this weekend.

Thank you.

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.
 
jlhuge
Going along with the "think" portion of this thread, let me throw out a few thoughts I've been having on this. Note that I haven't experimented with the drying curve much, but I will be doing so here shortly. Most of these thoughts come from my study into applied organic chemisty (i.e. cooking).
When we look at what the net result is from roasting the beans, we are trying for two major things; Maillard Reaction and Caramelization. This is where our major flavor development will happen only at higher temps (400+ for Maillard). As such drying would be essential in the process. I can see the importance of an evenly "dry" batch before starting the main roasting phase, but I don't know that the time of the drying phase would make much difference other than as an easier indicator than bean hydration level.
- Justin

West Bend Poppery I, strainer, shop-vac for cooling and chaff control.
 
Ringo
Jhuge I agree with everything you said. I think when I cup a coffee and its better with 4.5 min drying instead of 5 min for whatever reason I was drying it too much. Lot of good info coming out in this thread.
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
 
Barrie
This is very interesting to me, as a GC user, and must say straight away that I find the comments so far very confusing as to detail, particularly because of the different equipment used. The objective is clear and it sounds as though it is worth pursuing. The problem with a GC is the vast difference between the temperature read out and the bean mass temperature. I am currently using a profile as follows; Preheat/beans in, with temp set to 300 for 5 min/482 to first crack/440 to the end. I have just about decided that, with the few beans I have tried with the early drying phase, the result is a better taste than my previous Preheat/482 with no drying phase. That said, I have no idea what bean temperatures are at 5 min. Is it long enough? Too long?
I generally find that 1st crack occurs somewhere about the time the temp readout reaches 460, regardless of the time it takes, drying phase or no drying phase.
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
erik82
I'll give it a try on the GC. I always pre-heat the GC to 320F (160C) for 5 minutes and then dump in the beans and have a drying phanse of 5 minutes on 300F (150C) which doesn't get the beans to yellow. Yellow occurs somewhere around 8 minutes which seems to say that the GC is slow in transferring heat to the beans.

Maybe it's better to heat up the drum at 356F (180C) and then dump the beans. Drying it for 3 minutes at 356F (180C) and after that slowly reducing the temp to 320F (160C) in 2 minutes time to keep the heatingelement on most of the time and not have a too large drop in temperature and still be able to get a nice ramp to First Crack. From 320F (160C) to 464F (240C) will take around 7 minutes in my GC and before First Crack.

For me it's better to try and keep the heating element on the whole time to get up to First Crack to get a more even roast. Starting at a higher temp in the ramp up will only result in the heating element switching on and off when it reaches 464F (240C) which will be much sooner because of the higher intial temp.

The biggest test is to not damage the beans by putting them in a drum that is too hot and burn them on the outside. I'll have to do some test with this and see what the best temp is to put the beans in the drum and get to yellow in 5-6 minutes.
Olympia Cremina 2013, HG one 83mm #0083, Gene Cafe.
Also Zassenhaus grinder, Chemex, Abid Clever Dripper, Kalita Wave, Aeropress, Hario Buono, Bodum Cafetiere and Bialetti Mokapot
 
Ringo
[quote]Barrie wrote:

This is very interesting to me, as a GC user, and must say straight away that I find the comments so far very confusing as to detail, particularly because of the different equipment used. The objective is clear and it sounds as though it is worth pursuing. The problem with a GC is the vast difference between the temperature read out and the bean mass temperature. I am currently using a profile as follows; Preheat/beans in, with temp set to 300 for 5 min/482 to first crack/440 to the end. I have just about decided that, with the few beans I have tried with the early drying phase, the result is a better taste than my previous Preheat/482 with no drying phase. That said, I have no idea what bean temperatures are at 5 min. Is it long enough? Too long?
I generally find that 1st crack occurs somewhere about the time the temp readout reaches 460, regardless of the time it takes, drying phase or no drying phase.

If you do not have a bean probe time how long the beans take to first turn dark green and then yellow. The time to dark green should show if the preheat was right and when beans yellow I think drying is over. I believe color is more important than temps at this stage.
[/quote]
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
 
allenb

Quote

Barrie wrote:

This is very interesting to me, as a GC user, and must say straight away that I find the comments so far very confusing as to detail, particularly because of the different equipment used. The objective is clear and it sounds as though it is worth pursuing. The problem with a GC is the vast difference between the temperature read out and the bean mass temperature. I am currently using a profile as follows; Preheat/beans in, with temp set to 300 for 5 min/482 to first crack/440 to the end. I have just about decided that, with the few beans I have tried with the early drying phase, the result is a better taste than my previous Preheat/482 with no drying phase. That said, I have no idea what bean temperatures are at 5 min. Is it long enough? Too long?
I generally find that 1st crack occurs somewhere about the time the temp readout reaches 460, regardless of the time it takes, drying phase or no drying phase.


Barrie,

I'm sure many GC users are getting very good results by using an ET of 300 for 5 minutes for the drying phase of the roast but, if you want to achieve the level of drying we're aiming for in this thread you're going to have to maintain an ET higher than 300 during the last 3 minutes of the 5 in order to bring the BT up near 300F. Or, if it's impossible to program the first 5 minutes into two steps then maybe choose a higher starting temp to enable you to hit yellow by 5 min.

As Ringo stated, the shift from dark green to yellow is a much better indicator for knowing you've achieved a BT somewhere near 300F than trying to interpolate temperature readings on the Gene. I'm assuming the Gene has a large enough heating capacity to get the coffee to yellow by 5 min but if this isn't the case then push for as close to 5 as you can.

The point of this thread is to point out that there are various ways to get your beans to the end of the drying phase. Some ways more effective than others and to be sure to experiment regardless of roaster type. I've found with drum and fluidbed big differences in the cup by tweaking this phase of the roast.

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

Barrie,

I'm sure many GC users are getting very good results by using an ET of 300 for 5 minutes for the drying phase of the roast but, if you want to achieve the level of drying we're aiming for in this thread you're going to have to maintain an ET higher than 300 during the last 3 minutes of the 5 in order to bring the BT up near 300F. Or, if it's impossible to program the first 5 minutes into two steps then maybe choose a higher starting temp to enable you to hit yellow by 5 min.

As Ringo stated, the shift from dark green to yellow is a much better indicator for knowing you've achieved a BT somewhere near 300F than trying to interpolate temperature readings on the Gene. I'm assuming the Gene has a large enough heating capacity to get the coffee to yellow by 5 min but if this isn't the case then push for as close to 5 as you can.

The point of this thread is to point out that there are various ways to get your beans to the end of the drying phase. Some ways more effective than others and to be sure to experiment regardless of roaster type. I've found with drum and fluidbed big differences in the cup by tweaking this phase of the roast.

Allen[/quote]

I am not seeing yellowing beans until about 8:00 min with this profile, and 1C at about 13:00. This is the first I had heard of a darker green phase and must not be observant as, if quizzed, I would have said that they just gradually pale before going to yellow then tan. As we all know, of course, beans differ. I am currently working my way through some Colombia Pedregal and they seem to be a bit slower to reach each roast phase.
Incidentally, Allen, the temperature settings are infinitely adjustable on-the-fly, up to 482, so one can work with any profile within the heater capabilities of the device. With my next roast I am sure going to look for that darkening early on.
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
erik82
Did a roast yesterday to try and get the time to yellow down to around 5 minutes instead of 8:30 minutes. Started by heating up the GC with a temp of 356F (180C) instead of 300F (150C) for 5 minutes. Then dumped in 325 grams of Panama Bouquette and started roasting the first 3 minutes of drying at 356F (180C) and after 3 minutes slowly brought the temp down 2-3F every cycle of the heating element eventually ending up at 334F (168C) at the 5 minutes point. Then started the ramp.

The result was very good. My normal time to yellow is around 8:30 minutes and this profile reduced that time to around 6:30. The ramp up was very nice and the more heat drying phase didn't damage the beans. The result was a nice and even roast. The total time of the roast was 16:45 minutes where it would normally take around 18 minutes. Time to Frist Crack really starting was around 12:45 minutes.

I'll report back in a couple of days with the result tastewise.
Olympia Cremina 2013, HG one 83mm #0083, Gene Cafe.
Also Zassenhaus grinder, Chemex, Abid Clever Dripper, Kalita Wave, Aeropress, Hario Buono, Bodum Cafetiere and Bialetti Mokapot
 
Ringo
The dark green stage is very early on. Its the first change you see in the beans. They go from the color you drop in at to an almost florescent or translucent green. Not really darker just brighter. Dark green tell me the bean has heated up and is starting to dry. Beans also start smelling like fresh cut hay. On my drum I like for this to be around 2 min "with lots of radiant heat" on the behmor it was later.
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
 
Barrie

Quote

erik82 wrote:

Did a roast yesterday to try and get the time to yellow down to around 5 minutes instead of 8:30 minutes. Started by heating up the GC with a temp of 356F (180C) instead of 300F (150C) for 5 minutes. Then dumped in 325 grams of Panama Bouquette and started roasting the first 3 minutes of drying at 356F (180C) and after 3 minutes slowly brought the temp down 2-3F every cycle of the heating element eventually ending up at 334F (168C) at the 5 minutes point. Then started the ramp.

The result was very good. My normal time to yellow is around 8:30 minutes and this profile reduced that time to around 6:30. The ramp up was very nice and the more heat drying phase didn't damage the beans. The result was a nice and even roast. The total time of the roast was 16:45 minutes where it would normally take around 18 minutes. Time to Frist Crack really starting was around 12:45 minutes.

I'll report back in a couple of days with the result tastewise.


For GC users:
I am increasingly impressed with the reproducibility of roasting stages in terms of the temperature readout on the GC For example, regardless of profile in my machine and environment, I arrive at amber beans when the temperature is about 400F. Similarly, first crack starts about 460F. Someone else (forget who) made this point in another section and thread, and I think it is a useful observation. Among other things, it highlights the importance of mentioning temperature when events occur, time being less important? Apropos of the drying phase, the "amber at 400" observation applies whether I use a drying phase or not. If the drying phase is set to 300 on the GC, then I imagine the beans are not dry at the end of five minutes. Sounds as though a drying phase set at 400 for five minutes might be good and I will give it a try (could be too long).
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
snwcmpr
GC users.
I went to look at the Gene Cafe website.
What are the 2 digital displayed numbers?
Is one the max temp and the other the current oven temp?
I want to follow what you all are saying, and just want to know what temps you are writing about.

Ken in NC
(A HotTop roaster)
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
MikeWI
The top number is set by the left hand dial (red) and is the temperature. It will switch back and forth between the current temp and the set point. The lower number is the time counting down from what ever you set it to with the right dial (blue). Both can be changed on the fly.
 
Barrie
No, the upper of the two temps (red background) is a temp read out. It is where one sets the target temperature. During a roast, the reading alternates between the set number and the temperature of the air leaving the container. There is no measure of bean mass temp.

The lower readout (blue background) is the time setting, which counts down as the roast proceeds. When one goes to Cool, it zeros and counts up.

In the GC section there is a very interesting thread discussing the difference between bean mass temperature and that of the exiting air. The general conclusion (others will correct me if I am misstating this) is that there is a set temperature at which the cracks occur, regardless of the bean and how one gets there, and it looks as though, during a run, each GC machine has its own differential. For example, with mine, 1C occurs at about 460F, exit temperature. On the other hand, if one were to leave the machine on indefinitely, I assume bean mass and exit temperatures would tend to equalize

Both the set temperature and the time can be adjusted at any time during a roast, but not air flow rate or heat intensity. The heater is either on or off, and one can see the exit temperature "servoing" once the set temperature is reached.
Edited by Barrie on 02/15/2013 3:47 PM
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
az erik
As someone who's currently fighting this with my HT these times help me a bunch in giving a target to shoot for. I have a BT probe but it's a T-typ TC and I on't have a T-type reader currently (waiting on Jim's TC4C currently) I have just about given up with the HT's temp read out and the timer as it's backwards way of thinking while trying to remember how many min was on the timer when I dropped the beans in.

When I first got my HT i sped past the drying using the Auto setting which seem to do nothing. I had a Tanz turn out UBBER bright but rocked in a latte. After I stopped dropping at the 170 degrees and upped it to 200 to 215 I get all kinds of different results. My Fan causes more confusion to the ROR as I ha ve no actual way to measure it I have to guess but 100% temp to 290 degrees and then down to 70% power with 25% fan until 315 to 320 doesn't appear to be yielding me what I wanted. It appears that the drying phase ending around 320 on the HT is about 10 degrees short of going slightly yellow.

I tried using my K type reader with little luck as it reads about 50 degrees F higher than it should so I'm holding out till the TC4C arrives. It'll be very interesting to see what my actual ROR is when I can graph it and read it.

This post is very helpful for sure.
 
snwcmpr
Thanks Barry, I don't know the GC at all.
I use BMT in my HT.
az erik, I drop at 375 on the HT temp.

Ken
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
Barrie
What I am now wondering is whether those with professional or near-professional roasters have a need to calm their beasts down in the early phases to permit drying, whereas the amateurs with machines that generate less heat are coming from the other direction, struggling to get to roasting levels with appropriate speed? For example, from a cold start with my GC's heater turned full on (the only option) it reaches 400F container air-exit temperature, with amber beans, in 7 minutes. The yellowing process has taken place in the previous 30 sec, say. Have I not just gone through a drying process without any preheat or targetted drying phase? If I let the roast continue at this point I reach first crack at about 12 min.

I know the answer to the "what's wrong with that?" question (it's in the cup), but is it obvious to the experienced that this can be improved upon and, if so, why? I have a fair number of roasts and cuppings under my belt but would like to match theory with practice.

I believe Warren Buffet once said "It may work in practice but it will never work in theory." BBQ grill
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
Barrie

Quote

Barrie wrote:

No, the upper of the two temps (red background) is a temp read out. It is where one sets the target temperature. During a roast, the reading alternates between the set number and the temperature of the air leaving the container. There is no measure of bean mass temp.

The lower readout (blue background) is the time setting, which counts down as the roast proceeds. When one goes to Cool, it zeros and counts up.

The heater is either on or off, and one can see the exit temperature "servoing" once the set temperature is reached.


I must apologize for an error, as I now realize that the GC has two temperature sensors, one just outside the air-entry end of the container, which is the source of the digital readout, and one at the exit end, acting as a sentry, so to speak. So it is logical that the readout will always be higher than BMT during roasting, and lower during cooling.
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
snwcmpr
....... one just outside the air-entry end of the container ....
Is that ambient6 air, as in outside temperature?

...... one at the exit end, acting as a sentry ......
And that would be a reading of the oven temp?

*****

I get confused when you GC roasters are relating temperatures, and can't figure if you are relating the temp set as a max or the actual temp at the exit.

But, like I said, I don't have a GC, and probably won't get one. But I am interested in how you are roasting, so I can roast better and make a roaster, some day, that actually roasts well. I am therefore trying to follow this envisioning what you are doing to better understand what you are saying.

One note: My BMT rises above the ET at about 404-415?, depending on several factors. At that point, I learned that the heat is generated inside the bean more than from the oven.

Thanks for understanding my faults,
Ken in NC
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
Barrie

Quote

snwcmpr wrote:

....... one just outside the air-entry end of the container ....
Is that ambient6 air, as in outside temperature?

...... one at the exit end, acting as a sentry ......
And that would be a reading of the oven temp?

*****

I get confused when you GC roasters are relating temperatures, and can't figure if you are relating the temp set as a max or the actual temp at the exit.

But, like I said, I don't have a GC, and probably won't get one. But I am interested in how you are roasting, so I can roast better and make a roaster, some day, that actually roasts well. I am therefore trying to follow this envisioning what you are doing to better understand what you are saying.

One note: My BMT rises above the ET at about 404-415?, depending on several factors. At that point, I learned that the heat is generated inside the bean more than from the oven.

Thanks for understanding my faults,
Ken in NC


>>>....... one just outside the air-entry end of the container ....
Is that ambient6 air, as in outside temperature?<<<

No, the design of this thing is such that a fan blows ambient air over a "1200-1300 watt" heater and into the rotating container. The sensor is placed in the pathway between heater and container. There is one digital display of temperature. This can be adjusted on the fly and is the target for the temperature of the air entering the container. During a roast, this display changes, alternating every two seconds between the set target and the current temperature of the entering air. When the target temp is reached the heater switches on and off, servoing around the set point.

>>>. one at the exit end, acting as a sentry ......
And that would be a reading of the oven temp?<<<

It is reading the temperature of the air as it leaves the rotating container, but that information is not displayed. As I understand it, the purpose of the exit sensor is to detect over-heating, i.e. real or impending fire, and switch the thing off?

I have e-mailed the U.S. distributor and the Korean home office, looking for confirmation of this info. that I obtained from an Eddie Dove review.
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).
 
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