End Bean Color and Bean Development are Seperate Issues 🙀



In short: Bean color is the result of the momentum and the end temp of the Millard phase and Development is beginning after the Millard but before 1C through crack and after. Graphs, puzzles and elaborations to follow…

How to Taste Coffee
Anyone roast into second crack on the Ikawa?

Looking forward to them …


So this color gradient depicts a fairly accurate color transition of beans as they go through this profile.

Fig. 1: Bean Color Gradient: Marshal Etheo (v. 4)

Fig. 2: Flavor Development: Marshal Etheo (v. 4)

This is the flavor development, but it is not so linear (pun), or cut and dry like displayed. This figure can be misleading and is only used to show when the flavors stages are and not potentially where they could be. Because if I were to speed through the Fig. 1 yellow, the green flavor in Fig. 2 would be expanded. But the beginning color of green/yellow/brown is aroma, and the flavor I would say starts from the second (bright) green line @7:00 according to Sweet Maria’s video where Tom tastes the whole roast. A fairly entertaining video can be found here: https://www.youtube.com/watch?v=1OGFui3_5YU

Also to note, in my experience, it has been difficult but a few times I can smell the green veg or maroon fruit coming from the roasted beans as it enters in these parts of the roast.


Figure 3: Roast Color Development Editing

This is not factual but my imagination of where flavor/color develops for this type of profile based of the curvature of the application of heat. So if when I change around a profile I am using this color layout of where I think flavor/bean color will be and while I change the profile around while keeping the general curve it would follow the general rule of the color layout for both color and flavor development as one graph.

Figure 4: Speed of Color Development

This (based on my roasting) is the general outside color that all beans go through, It’s important to note that as the length of time gets longer the green of the coffee fades to yellow, and does not stay a “hardy” of a green as time continues. A very long time ago I shot strait up to 500*F in 1 minute but the roaster could not, this was an extreme test, obviously but In the extremes I do not believe this color sheet applies. But the green was vibrant.

I think it is very important to note that these are not made to the nth degree of perfection and a fairly rough estimate as best as I can do based on my very limited knowledge of using image/color editing software. Also the color of the outside bean is getting a good/nice smooth outside and not the bumpy…oh this is washed…outside, you can get a smooth outside if it’s washed processed btw, it’s all about heat application.


I forgot to mention, that this is the ramp for this style of profile curve that realllllyy makes the brown. How far the 3rd point moves up and how much speed that ramp has can make it really brown. This one also plays a strong role (I feel) with getting washed coffee’s more even on the outside.* This segments’ length I like to keep pretty long (of the total roast), because a longer segment gets into that malty…very juicy, thick, lush mouthfeel. Not to try and sell it that hard and I should say that I’ve really only tested this on 3 Ethiopians, 1 Brazil, 1 Papua New guinea…so not a lot at all. And I really hope that I can get some feedback and see what people think after testing/trying this style (minus personal preferences). This curve is based on Rao based ideologies, smooth curve etc, but the development time ratio is very different. And I am usually stopping 5-30sec after first crack, usually I try something like 5-7s, 10s, 15s, 20, 25s so really what I’m saying is if I want to extend the development I am moving by 5 seconds.

*based, I feel/guessing on how the segment right before, length/heat(height)/fan is drying the beans. I don’t know yet if it should be fast or slow. What beans prefer what, or what is a good range to be in. So :slight_smile: hope this helps.


End Point effects things like end color

  • If it’s too fast = astringent sharp roastey taste.

  • Too slow can bake out flavors, thinning the strength and complexity

Purple arrows mess with texture aka mouthfeel

  • the higher hemp of this point the longer the roast has in higher temps = viscous mouthfeel

  • loss of acids for acidic flavor or acidity to be developed into fruit flavor

The lower and steeper the ramp up to the “development”/last segment keeps more acids (yellow arrow).

This Millard/Caramelization ramp leads to how acidic the coffee is, not long enough and it wont taste acidic but will taste vegetal, over shooting the fruit will lead to long(er)/steady ramp will lead to that marshmallow/vanilla/sweet wood (brown arrow).


An experiment to try… I think is to put a point the the above profile at 400F at the 5min mark and then tweek the next point.

I feel as though I have been maybe too extreme in the length of the Millard phase, spending too much time…yielding baked notes on the hot cup, while still managing to get the blueberry on the cool cup with the Ethiopian from Sidamo. I have been trying to understand what is the difference from the ferment flavor vs the orgin flavor…but I am digressing from the original point I wanted to make.

  • 400F is the beginning of yellow/Millard, try not to spend too much time in it.

Enough time spent in Millard is good to help:

  • Help the bean expand later

  • Gives a nice/full textured mouth feel (Like how syrup feels in the mouth, because sugars break down to acids, and acids like to move between acid and not acid, giving a buffer/viscous feel)

To much time in the Millard:

  • Bake out flavors, leaving little to nothing to be developed

  • Produce bready, baking spice aroma in the hot cup. or can kill off all acids leaving a flavor void in the middle of the cup.

Since 400F is the start of Millard/yellow/gold, maybe I should be faster after 400F and keep the last segment the same…or extend it at little by starting development at the same temp it is now but sooner (because of the faster speed after 400F)…

What have I done wrong?

It should be noted, that even though I have tried this profile on a couple of different varietals, processing and regions. The Marshal Etheo profile has only been great on Africans (mainly Ethiopia), dry processed, heirloom varieties. Not to say it can’t work but that the main shape can stay but would require adjustments (yet undetermined) for different beans/regional etc.


Update: I have no doubt acids can have a texture effect, but I think it is not to say that the acids are the only thing contributing to mouthfeel. More or less I’d add that the breaking down of the bean, also has a positive relation to mouthfeel. Which also happens in the Millard and post Millard altering the balance of acids and polymers (from the cell wall), please forgive the science.