Ok, guys! I see a lot of great conversations on this site but it seems to me that far too few of them are actually about the art/science of roasting. Most discussions focus brewing and retailing- which is totally fine. However, I'd like to discuss the reason we're all here.


It seems to me that, as with being a barista when pulling an espresso shot, there are a limited number of variables at work during a roast.


When pulling a shot a barista balances: dose size, grind size, brew time, water volume in, and coffee volume out. The result of the equation is the extraction and the taste of the espresso.

Each of these variables has a somewhat predictable effect on the extraction and taste of espresso. That, of course, is another conversation.


Similarly, a roaster has in the works his own variables: batch size, bean size [and water content], roast time, air temperature, drum temperature, bean temperature, and airflow. I would like to see an informed discussion as to how each of these effects the outcome of a roast.


We can discuss batch size by asking, among other questions: what characteristics are common among roasts over 20lbs and what traits are common in smaller roasts? For example, do smaller roasts tend to have certain cupping results? Do larger roasts?


Roast time is an interesting topic because it is directly correlated to each other variable.


The question I have the most difficulty answering as a roster is: where does an increase in airflow have the greatest impact? Is it in the time/temperature vectors or is it on the cupping table?


How can we dissect these elements, and then reconstruct them for a fuller understanding of coffee roasting?



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Thanks, James. I very much appreciate your effort to stay on topic. And your information is not only very interesting but I think a great point at which to begin our discussion.

So, in your opinion, what is a low drop temp? What is high? What do you think might be the result of a mid level drop temp? Do you see faster turn arounds with higher temps?

James Tooill said:

I do agree that many roasters are pretty secretive. I'm not sure if that behavior really protects any accounts(or proves that they are greedy assholes...), but I can see the thought process.

It seems that the original  post called for a discussion about roasting itself.  That might be an unreasonably broad topic. Could a discussion of initial drop temps be more manageable?  Here's a few thoughts for discussion.


Low drop temps:

-help low altitude coffees avoid tipping

-combat unneveness especially with naturals

-make sense if temperature of beans/air/machine is high

-seem to help develop mildly acidic fruit notes(strawberry/melon/red apple/grape) in some coffees

-are requisite with smaller batches

-can delay 1st crack in order to downplay some unwanted brightnesses especially in the case of very fresh green

-often necessary to develop decafs without scorching 


High drop temps:

-Can preserve acidic snap in higher altitude coffees

-Make sense if temp of beans/air/machine is lower

-Facilitate a faster approach to 1st crack which often brings out more acidic fruits(citrus/tropicals/raspberry etc.)

-Helpful with larger batches

-Faster approach to 1st crack might keep some brightness as the green ages ungracefully


These are just my own observations and theories about roasting on a Diedrich.

Your solution to a conversation about a conversation is to start a conversation about having a conversation about a conversation?  


Maybe you'd better rethink the notion that you 

have a pretty discerning pallate, a fine personality, smarts, and an analytical thought process that makes me, perhaps, more inclined to be a good scientific-style roaster than most.

I'm all for a discussion, but as Farmroast mentioned (who, might I add, has been in the roasting game longer than either of us), bring up a detail, and people will likely come out of the wordwork to throw in their say.  

Zechariah White said:

I began this discussion in the hope that other users would themselves ask pointed questions and we could begin to create a dialogue within this discusssion that would be FULL of different-direction pointed questions and answers regarding the roasting process contained under one main header. This would make it easier for people who are interested to follow the various discussions going on around roasting rather than wading through all the crap about why 17oz lattes are bad or ristretto shots are--- whatever. I was simply frustrated by the lack of discussion regarding the actual process of roasting under the roasters' discussion forum. It seems my efforts have paid off very little and only brought much criticism and negative attitude. WHICH is why, in the modern, computerized age, I have to disagree with those who say that personality is not a factor in what makes a good roaster.


 I, personally, am a barista/roaster/trainer because it is my way of incorporating all aspects of my SELF into what I do for a living. I have a pretty discerning pallate, a fine personality, smarts, and an analytical thought process that makes me, perhaps, more inclined to be a good scientific-style roaster than most. Artisan roasting, to me, is like playing a song by ear: I can barely do it. Tell me what key the song is in and what the time structure is and it all falls into place easily.


 I, of course, agree with all of those who have said there are no easy answers. Just to be clear, I wasn't looking for "answers" I was looking to inspire a conversation. Instead, it seems, we're having a conversation about having a conversation. This is very frustrating and just harkens back to the other lame conversations under this main forum.


I've been a barista since 2004. I began managing what was a very successful coffee shop in 2006. That same year I began an apprenticeship for a coffee roasting company which, at that time, produced the best cups of coffee I'd ever tasted. After my apprenticeship I went back to managing the shop and then I tasted counter culture coffee. I've never looked at coffee the same way since. I new my calling was as a coffee roaster, buyer, cupper, business person, etc. I bought a YM-2 in 2009.


So in the 5 years I've been roasting coffee I've learned a little. Mostly I've learned that if one wants to learn more about roasting they must shell out BIG bucks or roast, cup, roast, cup, roast, cup AND make very, very detailed roast charts and analyze the small differences in the numbers and the cupping results. While I've enjoyed every second of doing both of these things, I'd still like to encourage an open dialogue here regarding the process of roasting coffee. So, if you are a person who is not like minded, or who doesn't believe that roasters should feel obligated to help elevate the quality of production of their entire community, go find a discussion about 18 oz lattes or whatever it is you do want to talk about.





farmroast said:

Got a question or idea? Why not explore/try it a bit yourself first? Then post a more pointed question including details of what one has already found. There are so many things that can effect a roast. It's hard to know where to start with broad questions. Explain more about what you already know, reference what you've read, so those that respond don't have to write a book to include every possible variable that needs to be considered.

Have you read what's available to anyone in the online SCAA library? What Boot offers online? The Illy book? Stefan Schenker's investigations? Carl Staub's article on roast chemistry? Ulkers old classic. These are all available free online (except the Illy book). I even listed some of them with links on my blog. 



Personally I found Zechariah's diatribe verging on humorous.

 - that makes me, perhaps, more inclined to be a good scientific-style roaster than most.

And followed by

-Do you see faster turn arounds with higher temps?

Really asking that? Wadaya think? Rather basic scientific principle higher charge temp yields faster turn around all else being equal.


Bottom line in my opinion the best roasters have a firm yet ever growing foundation in the science of roasting which enables them to continually better apply the art of roasting. One without the other is but a shadow of what roasting can be. James' input indeed was both scientifically insightful and artfully useful.


In reality to learn the principles of roasting one does not need to shell out big bucks. Indeed it is about roasting and cupping ad infinitum. But this need not be on large batches. The same principles apply whether 1/2lb or 200lb batches. I spent 6 years controlled profile roasting thousands of batches, mostly 1/2 batches, before shelling out big bucks. Roast the same bean same finish temp modifying different stages of the profile different ways, sometimes half a dozen or more flights of a bean at a time. Repeat, repeat, repeat... and patterns emerge out of the darkness of ignorance. And there's no shame in ignorance, I am and always will be ignornant and hence always continue to learn.


Bring us your detailed roast profile(s) for a given bean, your cupping notes for the different profiles same bean, and if you then have questions on what caused the differences or how to change a profile for a different target result might be inclined to discuss concepts with a serious student of the bean.

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