Guiding the roast and handling heat

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
folkery
Posts: 4
Joined: 7 years ago

#1: Post by folkery »

I wanted to start a topic where we can share our insight on how the roast is guided with heat application and its variables. According to Scott Rao we want a high enough charge temp to build pressure within the beans at the beginning of the roast, so that this momentum can be carried throughout the entire roast. If I start well I will be able to end well.

I also want maximize the potential of the Maillard (yellow to orange) reaction phase and development time (first crack to drop)
Do these phases develop better with more or less heat? In Rob Hoos' book "modulating the flavor profile of your coffee" and I quote, a too slow development of the Maillard phase can flat line the flavor of your coffee, a too fast will not give proper maturity to the carmalization of sugars within the bean.

In your experience would you guide your roast using heat settings in a "n" shape?
(Example)
After charge temp, starting with low heat - (1.25kpa
Drying phase over, enters yellowing - (3-4kpa
Approaching first crack - 2kpa

Or would you guide the roast using heat settings from high to low?
Building momentum throughout the roast and tapering it off.

I understand there are many factors in play depending on process type of bean and density and overall approach for flavor.

I'm talking in general how you would guide a roast whether natural or washed. What was your approach?

edtbjon
Posts: 251
Joined: 9 years ago

#2: Post by edtbjon »

There are many Artisan graphs posted here where the roaster is either a gas drum roaster or possibly a Quest M3. As both Rao and Hoos are discussing from an e.g 15kg drum roaster viewpoint, let's keep the discussion within those parameters.
Regarding charge point, that is usually choosen to be below the point of tipping or scorching. But it can be radically lower than that. The idea here is to let the temp drop low enough so that you can use your burners at or close to full capacity without rushing through the drying phase in a couple of minutes. With this approach you do build up that momentum so that the beans do have enough inner pressure for the coming Maillard reactions. It's a matter of finding a "balance" so that you easily can navigate through the rest of the roast. If you do it right, it's easy to manipulate both the Maillard phase and the development phase, as you have the proper tempo (read: DeltaBT) at DryEnd.
How you adjust the burners is very roaster dependent.