hg-one.com: tools for building better coffee

Interesting professional roasters' discussion

Postby Marshall on Tue Aug 12, 2008 9:27 pm

You can't post there, but you can read an interesting thread by respected professional roasters answering a professor's questions about roast profiling and the effect in the cup: http://forum.coffeed.com/viewtopic.php?f=16&t=2286.
Marshall
Los Angeles
User avatar
Marshall
 
Posts: 2578
Joined: May 13, 2005
Location: Los Angeles, California

Postby RapidCoffee on Tue Aug 12, 2008 9:43 pm

Probably the same "Bear" who initiated an interesting thread on roast profiles on CG.
John
User avatar
RapidCoffee
Team HB
 
Posts: 3092
Joined: Dec 11, 2005
Location: Rapid City, SD

Postby Marshall on Tue Aug 12, 2008 9:59 pm

RapidCoffee wrote:Probably the same "Bear" who initiated an interesting thread on roast profiles on CG.

Certainly. The difference is who is answering.
Marshall
Los Angeles
User avatar
Marshall
 
Posts: 2578
Joined: May 13, 2005
Location: Los Angeles, California

Postby farmroast on Tue Aug 12, 2008 11:16 pm

Marshall
Thanks for the heads up and link, BUT I won't hold my breath waiting for much in details cause it just never seems to happen in public. There have been a few similar threads on RG during the past few years that I have been watching that have abruptly stopped after scratching at the surface along with the general wisdoms. Overall for specialty coffee it would be a good idea but for competitive professionals it doesn't make much sense to do so.
Hoping they prove me wrong,
farm
Ed Bourgeois
"agitation is important like grinder"
LMWDP #167
http://coffee-roasting.blogspot.com/
User avatar
farmroast
 
Posts: 1455
Joined: Jan 01, 2007
Location: Amherst,MA.

Postby another_jim on Tue Aug 12, 2008 11:54 pm

One of the reasons I left Coffeed -- every topic turns into ten posts by the usual suspects talking up their "craft experience," rather than answering the question, as if it were an advertising bulletin board from the 15th century. By the time that's done, everyone's eyes have glazed over in boredom and anything interesting posted to the thread is lost. If these usual suspects bothered to pick up any of the works on coffee research and perhaps a food science text to help decode what they are reading, they would be able to give a fairly precise answer to the question, since a lot of the required information is well known.

There are three basic things happening when you roast coffee: 1) water evaporates, 2) organic acids and aromatics break down or are boiled off, and 3) water, sugars, and amino acids combine in a chain of chemical reactions collectively called the Maillard reaction.

  • Water Evaporating This happens from the moment the beans are heated up to the first crack, when the remaining free water escapes. As the beans exceed 300F, a steam wave moves out of the bean from its center. This wave also starts the Maillard reactions (see below). Below 300F bean temperature, not much is happening except water evaporating. If the bean is too moist going above this, the bitter organic acids will not break down as quickly (see next section). If too much water evaporates, the Maillard reactions are starved, and the roast will be dominated by dry distillates. The drop-in temperatures or early bean heating should be adjusted to achieve this balance
  • Organic Acids and Aromatics Breaking Down or Boiling Off Roasts have to go to partway into the first crack, since this is where the chlorogenic acids that make unroasted coffee intensely bitter finish their breakdown. The smaller acid molecules and aromatics, which are responsible for the fruity aromas and acidic tastes start breaking down around around here. The longer the beans stay at temperatures above about 390F, the lower the acidity of the result. For instance, it is said that Italian espresso roasters stall the beans around the first crack to reduce acidity without reaching temperatures that caramelize off the sugars. Too much of this is a roasting flaw called baking, which overly flattens the flavor of the coffee.
  • Maillard Reaction Chains This is where the complexity of coffee is created, since these reaction chains are hugely complicated. However, there are some overall guidelines. The early Maillard reaction, from 300F to the 1st crack, creates nutty, toasty, and woody flavors. At higher temperatures, sugars stop reacting with amino acids and start caramelizing on their own, creating caramel, vanilla and chocolate flavors. Finally, also at higher temperatures, and when the water required for early Maillard reactions and caramelization runs low, the Strecker degradation changes the compounds created earlier in the roast to dry distillates: smoky, spicy and peaty flavors. The simplest lesson here is that these processes compete for water, so that taking longer in the ramp to the first will and less time thereafter will favor the woody, toasty, nutty flavors and reduce the caramel ones. Also, if the roast is to get very dark, the only way to avoid overwhelming distillate flavors is to dry the beans less (go as fast as possible earlier in th roast), so the Strecker degradation creating these flavors is controlled.

There is also the inconvenient fact that beans are 3 dimensional objects. Roasts faster than about 6 minutes will have significant differences between the inside and outside of the bean, and the inside can be under roasted; slower roasts will be more even. However, the slower a roast, the more the aromatics are cooked off.

So, after making sure one has dried the bean to the right degee in the roast below 300F, and balanced the flavor developments that takes place below and above 400F, one should roast as fast as possible.
User avatar
another_jim
Team HB
 
Posts: 8813
Joined: May 05, 2005
Location: Chicago

Postby farmroast on Wed Aug 13, 2008 1:33 am

What is done or must be considered to bring out desirable nuttiness? Tweaking my 2nd leg has really brought out the sweetness in my roast thanks to the ET thread and your suggestions.
Ed
Ed Bourgeois
"agitation is important like grinder"
LMWDP #167
http://coffee-roasting.blogspot.com/
User avatar
farmroast
 
Posts: 1455
Joined: Jan 01, 2007
Location: Amherst,MA.

Postby another_jim on Wed Aug 13, 2008 10:58 am

Sweetness and nuttiness are in competition, since the production of nutty flavors requires sugars and amino acids. The faster you go from 300 to first crack, the fewer the nutty flavors, and the sweeter the result. Your best bet is reducing the sub-300 warm up a bit, extending the leg to and through the 1st crack, and speeding up the end final leg. My first try would be keeping the overall length the same, taking a minute off the warm up and end, and adding two in the middle. This is the way I roast the Bolivian Cenaproc; for it, I'm looking for a dominant marzipan flavor, i.e. sweet and almond.
User avatar
another_jim
Team HB
 
Posts: 8813
Joined: May 05, 2005
Location: Chicago

Postby farmroast on Wed Aug 13, 2008 11:44 am

Damn, It's all starting to make sense!!! So the first trade off of sacrificing a bit of sweetness before first and a bit of fruitiness after first will gain in the nuttiness(when appropriate with the right bean). Going too long in the mid leg will continue to lose sweetness and head towards toastedness and then to woodiness? Generally seems that Pacamaras have this potential too, being careful because available sugars are less?
Ed
Ed Bourgeois
"agitation is important like grinder"
LMWDP #167
http://coffee-roasting.blogspot.com/
User avatar
farmroast
 
Posts: 1455
Joined: Jan 01, 2007
Location: Amherst,MA.

Postby another_jim on Wed Aug 13, 2008 2:46 pm

I find Pacamaras are tough to get right. The easiest is just to blast through the stretch to the first crack, go for sweet, and rely on the Marogagype genes to give you some of the characteristic wood in any case. But if you are looking for the signature taste, and the bean is high quality with lots of sugars, you can afford to convert some of those into flavor components -- the pre-first woody ones in this case, with a really light roast ending level to keep the Caturra style acids around. But truth is on my last two Pacamaras, by the time I was halfway happy with the result, I had roasted through the entire stash.
User avatar
another_jim
Team HB
 
Posts: 8813
Joined: May 05, 2005
Location: Chicago

Postby DigMe on Thu Aug 14, 2008 12:38 am

Excellent explanation, Jim.

brad
DigMe
 
Posts: 273
Joined: Oct 14, 2006
Location: Waco