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300F to 350F (150C to 175C)
Unta
Top  #21 Print Post
Posted on 12/20/2011 10:34 PM
Some info I stumbled across from Jim S. link to the thread is at the bottom.

Posted Tue Mar 18, 2003, 1:36pm
Subject: Re: Roasting Profile ?

A roasting profile isn't the heating temperature, but the graph of bean temperature over the course of the roast.

Since these cannot be measured directly (their surface is a wrinkled insulator that doesn't transfer heat very well), one usually measures air temperature where it has equalized with the beans -- in a drum roaster this is the still air inside the bean mass, in an air roaster it is the flowing air after it has been in contact with the beans longest, usually close to the exhaust point.

I've appended a profile here that includes roasting milestones (I was calibrating my temperature readings to duplicate a Hottop roast for an experiment - results soon).

Roasting profiles vary. Drum roasters take a long time to get to the first crack, and usually finish fairly quickly, in 3 to 5 minutes. Air roasters go quickly to the first crack, and slow down, some more than others, at that point.

I'm currently using a profile that goes to 300F as fast as possible, spends four minutes going to 350F, and finishes in 5 minutes thereafter. I find the slow ramp from 300 to 350 mutes the acidity without toning down the origin flavors as much as my previous profile that slowed down after the first crack was done (ca 410F). Slowing down a lot during the early first crack (375F-400F) is rarely advisable, since it's said to "bake" the beans

http://coffeegeek...roast/8492
Sean Harrington
educate.
 
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allenb
Top  #22 Print Post
Posted on 12/21/2011 7:44 PM
Interesting to hear of a slow post-dry to 350 being able to mute acidity. I've never tried going slow during this phase of the roast.

I recently experimented with going much slower than I'm accustomed to from 1C to finish (fluidbed) to try and achieve a bit more body. I went from a little less than 2 1/2min (8 degrees/m) to 3 3/4min (5 degrees/m) ending at the same finish temp with a really nice Tanzanian.

While dry fragrance and body improved a lot, it went from having a good balance of acidity to having so little it was flat. I roasted again today with 3 min post-1C and will give it a try tomorrow.


Allen
Edited by allenb on 12/21/2011 8:12 PM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Unta
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Posted on 12/21/2011 8:24 PM
Im having similar results Allen.
Sean
Sean Harrington
educate.
 
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endlesscycles
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Posted on 12/21/2011 11:13 PM
That's some old info. You can do a lot of stuff with coffee, and your tastes will guide you..but what happens from 309-378 is not worth lingering on, IMO.
-Marshall Hance
Asheville, NC
 
Unta
Top  #25 Print Post
Posted on 12/22/2011 12:02 AM
I appreciate your opinion Marshall. Though I was linking to info that mentioned a portion of the roast profile that we were discussing in this thread.
Age of info isn't very important IMO.
Everyone here is at different points in their evolution.
You're likely experienced enough to be able to just disregard and that's likely based on experience. Some of us aren't or simply don't choose to be.
Whats your opinion on what is happening from 300-350, I would be curious of your insights.
Sean
Edited by Unta on 12/22/2011 12:04 AM
Sean Harrington
educate.
 
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seedlings
Top  #26 Print Post
Posted on 12/22/2011 7:56 AM

Quote

endlesscycles wrote:
That's some old info. You can do a lot of stuff with coffee, and your tastes will guide you..but what happens from 309-378 is not worth lingering on, IMO.


Interesting! You must have "one profile" for that range?

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
 
Bhante
Top  #27 Print Post
Posted on 12/22/2011 11:17 AM

Quote

seedlings wrote:
Up to 300F is drying , 350-390F is sugar caramelization, what is happening during the roast from 300F to 350F?

I don't believe you can say that drying is completed by 150 Centigrade (300F). My experience seems to be that you can get a lot of steam produced at higher temperatures. Up to 150 Centigrade I would associate with the loss of unbound moisture (and maybe also loosely bound moisture?), and 150 to 170/180 Centigrade I would associate with the drying off of bound moisture. If you have hydrated copper sulphate crystals they are blue crystals, and they may seem perfectly dry but they still have bound water which is not chemically bound in the sense of the carbohydrate molecule, but nevertheless it is bound to the copper sulphate molecule and needs heat energy to remove it. If you put it in the hot sun for a week it will remain blue, but if you bake it in the oven the water will come off as steam and the crystals will turn to a white powder. I think cobalt chloride is a better example but my chemistry is too rusty - if I remember rightly cobalt chloride will require a temperature substantially above 100 Centigrade (about 180?) before the water of hydration will be removed. I am assuming that between 150 to 170/180 Centigrade there is a similar type of water of hydration given off from the coffee - this should be about 5% of the weight of raw coffee - but maybe it could also be that the water given off in this temperature range results from a chemical change. In the text cited earlier in this thread there is a brief mention of sugars being broken down releasing water, but there is also the breakdown of organic acids, which will also give up water, and this I reckon should be happening around 170 to 180 Centigrade. Does anybody know much about the breakdown of organic acids?

Certainly the 150 to 170/180 Centigrade range (302 to 338/356 Fahrenheit) is critical to the roast profile, and can make or break the roast. This range can be used to reduce the acidity in an over-acidic coffee and facilitate the subsequent development of a full body, or if it is lengthened too much it can destroy the body.
 
endlesscycles
Top  #28 Print Post
Posted on 12/22/2011 4:03 PM

Quote

Unta wrote:
I appreciate your opinion Marshall. Though I was linking to info that mentioned a portion of the roast profile that we were discussing in this thread.
Age of info isn't very important IMO.
Everyone here is at different points in their evolution.
You're likely experienced enough to be able to just disregard and that's likely based on experience. Some of us aren't or simply don't choose to be.
Whats your opinion on what is happening from 300-350, I would be curious of your insights.
Sean


Well, I'm not going to speak on behalf of Jim Schulman, but my understanding is his profiles have changed since then, and presumably as a result of improvements in his roasting skills and ability as a taster, as well as improvements in both actual coffee and the brewing tech available. So on all sides, coffee is better.... I don't think old roasting styles are as relevant to what is possible now.

Maillard reactions begin at 308....so flavors associated with them are increased by lingering between there and first crack. Other things happen, but that's the most obvious in the cup within the range you mention.

In all honesty, I've never once tried going slow from 300-350. Realizing that, I'm kinda curious now.
-Marshall Hance
Asheville, NC
 
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