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Toward a Unified Understanding of Roast Development for Sweetness
Hello from Columbia, Tennessee!
Toward a Unified Understanding of Roast Development for Sweetness
By Wallace Hebert, aka BearPaw

It is rare to find a song lyric on the Internet without an error, as volunteers post text on sites based on their hearing of the original song. An example is the SteelDrivers song ending with the wonderful line, ?West of where the sun sets, Where Rainbows Never Die.? Auditors on the Lyric sites have posted, ?waste away the sunsets, Where Rainbows Never Die.? Quite a difference, one would admit.

So when we wade through posts on coffee websites, we often encounter ?Post-Os? which are like typos, slips of the mind or slips of the fingers, or often both together. I catch myself doing them all the time, and they are pesky to catch in a re-read. I am telling you straight up, I have detected several in the material I have assembled here, and fixed them as I went, indicating the intended words or values using parentheses. Once an editor, always an editor, or a Comma Suturer as I usually position myself.

Coming to this task with a hundred Behmor roasts, a hundred Gene Caf? Roasts, and twenty Hottop roasts, I am aware of the difficulty of applying roast theory from Willem Boot, Thom Owen, James Hoffman, or any other authority to one?s specific home roasting equipment. Much advice about roast velocity comes from folks with gas and commercial roasters featuring instant variability in the heat source and rapid fan control and cooling capability as well.

Seeing spacecraft coffee roasters depicted on the site, I marvel at all the ways we roast the magical coffee bean. My own grandmother Hebert roasted in a skillet or a gas oven at the turn of the last century, and tried to teach me, but I never had the patience in the 1970?s to replicate her skills; I always scorched the coffee.

Coffee roasting is an Art dependent on sensory input. Science can be enlisted in its service, and Ruling the Roast most precisely are those with bean mass thermometry. However, all the variables present, even when roasting the same coffee a month later, make it unlikely any of us will ever achieve automatically replicable, ?Set it and forget it? profiles. We homeroasters are all artists, and we might as well make brown berets for saying ?Artiste du caf?.? (I?ll buy one!)

Synthesizing from all my reading on the roasting process, much of it on, folks seem to talk about five distinct phases of a successful coffee roast.

1. Preheat, drop, and recovery to boiling point of H2O in bean mass
2. Drying phase to 300F
3. Proceeding to First Crack
4. The Roast target phase, Four minutes to Second, but sooner if City/City + desired
5. Cooling phase

With anything less than a commercial gas sample roaster, we are going to be severely challenged by one or more of these phases. Preheating and cooling for Behmor users, Cooling for a Gene user, reliable thermometrics without bean mass probes, Rate of Rise control without all manner of gadgets and technological distractions from the aromatic, acoustical, and gustatory perfection our Art pursues. So let?s get our Phasers out!

Bean Preheat Phase?Preheat, bean drop, rebound, rise to boiling point of water.

What is the optimal time to this 210F or thereabouts Bean Temperature point? No question you can unevenly develop a roast at this phase as Allen B points out. But the answer seems to be two or two and a half minutes,
--Just look at the different profiles on Joe Behm?s roaster. Hot right off the bat on P1 and P2, gentler first phase on P3-5. Preheat or not, beans in or not. Behmor users talk about this all the time.
?Gene Cafe is heating element air blown by fan across the undulating beans and measuring temp at the outlet, but lots of interest in drying time and temperature on profiles and thread posts.
--Hottop threads on this site benefit from lively discussion from Ken and Ginny on drop temps. Consensus: Don?t worry about too hot drop environmental temps and quick rises, just go for it. Once boiling point temperature is reached water is coming out and beans will not scorch.

Roast Development Phase

Second and Third Phase in my opinion, need to be understood as one unit and the key Roast Development Phase: Drying, color changes, sugar changes, ramp-up to First Crack. Two or three minutes are needed at 200-300 degrees to dry thoroughly, depending on bean hardness, says Allen?s thread. So what comes after that, do we rush to 370 (Hottop?s 1C Environmental Temperature) so we can get to 1C earlier. How about just a little slower and maybe a little sweeter?

Taking a Staub at Sweetness as a roasting goal:

This section taken from a blog: Deaton?Got Coffee
This blog is the work of Deaton Pigot, an Intelligentsia roaster. http://deaton.wor...sweetness/
Says Deaton:
?Following Carl Staub?s theories of sucrose development I prolong the ?golden period? where the color of the once-green coffee bean changes from pale yellow to bright orange. We allow the roaster to gently heat the beans and maintain a low minute-to-minute temperature increase. It is in this stage of the roast between minutes 2 and 7 ? 8 and at 230-340?F that the Polysaccharides split off into Monosaccharides building a foundation of simple sugars for us to work with later on.

?Between 7 and 12 minutes and 240-392?F (Oops, Post-O?340-392F, in the context I think is what he meant--Bearpaw), we are starting to dig into the foundation of sweetness that we had just built, and the beans start the Maillard reaction, which is the caramelization of those simple sugars.

?At the beginning of this period (340-392) we start to apply more heat so we can stay ahead of the exothermic reactions. If the environmental temperature stays ahead of the bean temperature, we are less likely to lose the simple sugars that have developed as paralysis (pyrolysis says BearPaw) of the cellular structure (occurs) and first crack (approaches).

(BearPaw Note: I interpret this to agree with Jim Hoffman?s statement that we should just get through this 340-First Crack period rapidly because ?nothing good is happening here.? Hoffman, in his blog discussions, also agrees with the Staub theory that up until 340, some polysaccharides are breaking down into monosaccharides. Also, Randy Glass has a second, quicker Hottop profile on the Hottop website aimed at preserving varietal characteristics that likewise scoots along at this point.)

NB: Of course we must remember that if we are not using gas to roast, but electric, such as my Hottop B2K, we have to anticipate first crack with a heater adjustment at 340-360 to permit rampdown before the exothermics of first crack begin at 370ET--BearPaw.

Deaton continues: ?If I have come into first crack with enough heat and momentum I will typically turn the gas to its lowest setting and just ride out the rest of the roast. The amount of time that it takes between first crack (I measure from it?s most volatile/ noisy) till the point that I drop out will also greatly impact flavors into the cup. I feel it is between these two points that is when we will inevitably start to introduce carbon into the beans make up.

Roast Target Phase?Again, Deaton?s comments.

?I performed a little experiment with my roasting before Jim Schulman arrived for his most recent visit this past summer. I took several coffees and roasted them all in 2 different ways, to the same final temperature but with either 2.5 minutes or 4 minutes between the onset of first crack and the end of the roasts (e.g. the speed of temperature increase after first crack was altered). I hadn't always been consistent in the length of this "intercrack" period and wondered what impact it had. The results were extremely obvious; the 2.5-minute interval produced dull coffee that was usable only if disguised in milk. The 4.0-minute interval produced some of the best results I've ever had. We compared simultaneously made shots from these two types of roasts (same beans, other parameters constant) in a blind tasting fashion and Jim and I both picked the slower (4 minute vs. 2.5 minute interval) coffees 100% of the time. It was that dramatic, but I would never have learned that without testing it. ?

This blog by Deaton is intriguing when you see how easily the times and temperatures of the two phases he is describing, i.e. polysaccharide breakdown at 230-340, and pyrolysis at 340-First Crack, overlay the consensus this discussion site has established for drying and time to first crack. His description of post first crack strategy also resonates well with the learnings on After first crack ends and City passes, we are steadily counterbalancing varietal characteristics with the progression of the char process--as we, and if we, prolong. As long as we would hit second crack at about 4 minutes, we can stop at any time after 1C concludes for City, City + or Full City, using Sweet Maria?s terminology.

For a description of how I have adapted these learnings for my Hottop roasting strategy, look under the Hottop threads for the conclusion of this post.

God Bless Y?all,
Edited by JackH on 07/28/2013 8:51 PM
Gene Cafe, Behmor, Aeropress, various pourover, biggins, heirloom coffeepots, Crossland CC1 with VST 18 and 15 gram baskets.

"How Good's the Coffee; How Bad's the Pie!"
Bearpaw, Thanks for writing this up! Still looking at it and I wanted to let you know that I made your link to Deaton's blog "clickable" in the post.


I hope nobody uses the quote on this post.......Grin
Edited by JackH on 07/28/2013 9:29 PM
Bear paw, that's a great write up. There is a lot of info in there. It's very seldom that I read so much and not see something I feel is not right. I bet you drink some great coffee. I will say on my roaster 4 min after 1st crack is too long to make the flavors I like. Good job with the write up
All you need in life is ignorance and confidence, and then success is sure. Mark Twain
Nice essay! I'm going to study and absorb it later. I want to learn more about controlling for sweetness. On the first read I only found one posto:


grandmother Hebert roasted in a skillet ON a gas oven

Just so you know, gas sample roasters aren't designed to profile roast artisanal coffee. Rather, they rarely roast above cinnamon roast, their purpose being to detect defects in coffee. I have to agree, the excitement of owning the smallest commercial roaster is too much for homeroasters to bear.

Deaton will be pleased to know that commercial roasters and coffee scientists prefer a long, gentle climb to the final roast point. One reason being that bitter trigonelline slowly decomposes with heat, but it takes time to accomplish. I've heard it referred to as a Maduro roast.
1 pound electric sample roaster, 3 pound direct-flame roaster, both handmade; modified Mazzer Mini grinder, LaSpaziale Vivaldi II automatic espresso machine. When the electricity goes out I make vacpot coffee from beans ground on my Zassenhaus hand grinder, and heat the water with a teakettle on the gas range.
Nice read.
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".
I go along with the whole "art of roasting" thing, but to me, it's all science, even down to the tastes or perceived tastes.
Ed B.
DreamRoast 1kg roaster, Levers, Hand Mills
Science it is but you must take into consideration when roasting, at least for yourself, personal taste.

You may roast an incredible bean but if my taste buds say ugh, well so much for science...


Edited by ginny on 07/29/2013 3:06 PM
It's taste. All the instructions for the HT suggest that I drop too late and scorch the beans. For some unknown reason that does NOT happen.
As Shunryu Suzuki said "Not always so."

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".
Thank you for sharing this! Given me something to think about for my next 'experiment'!
LPG Indirect Heat | 5kg Solid Drum Roaster | Beginner
There are so many variables, even the same coffee type will vary from one year to another. All you can do is use some general procedures and adjust for taste.

I do believe a slower rise after 1C makes a big difference as well as enough (not too much or too little) time in the "Drying" stage.
Nice post.

I found this page a while back and it has some information about effects of changing the roast timing.
I'm glad I finally took the time to give this the read it deserved. Well researched and nicely crafted.

My father was/is a wordsmith. I inherited none of that, but I do have an appreciation.
Cheers, -Scott
posts moved to endothermic reversal thread:


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