Development Testing

Development time is the part of the roast that occurs after 1st crack. It is measured in time but also as a ratio. Roasters adjust development in order to tune the tastes of the final product. Changes made in this part of the roast can have very significant effects.

Example:

  • Total roast time = 10:00 Minutes = 600 Seconds
  • Time to First Crack  8:00 Minutes = 480 Seconds
  • Development time = 2:00 Minutes = 120 Seconds
  • Ratio of development time: 120/600 = 20%

 

Test 1 – Updated 5/13/2017

Test: What changes does adding development time have on the measurements and taste?

Goals:

  • Gain experience roasting on the Ikawa

Roasting a washed Colombian on the Ikawa roaster. I defined 3 profiles with varying development times. Ikawa profiles are based on return air temperature, so they look a little different than a traditional bean temperature plot. I estimated that 1st crack would occur at 400°F (not quite correct) and used that temperature as the beginning of development. End temperature is fixed at 410°F. The first roast has 1:00 minute of development time and each subsequent roast, I added 30 seconds, so 1:30 and 2:00 for roasts #2 and #3. This added to the total roast time, so not only was I adding time to development, but also total roast time.

Ikawa roast profile example

Ikawa roast profile example

Ikawa roast log example

Ikawa roast log example

Profile #1

  • Total roast time: 10:00
  • Development time (based on 400°F): 1:00 (10%)
  • Development time (based on marked 1st**): 0:47 (8%)
  • Weight loss: 50g → 42.2g 15.6% loss
  • Colortrack (WB-GR): 62.26-62.77 Δ -0.51
  • Notes: **Not sure I marked 1st crack correctly. it’s quite different than roast #2 and #3 where I am more confident that I marked it correctly. Or first roast effect? Not sure.

Profile #2

  • Total roast time: 10:30
  • Development time (based on 400F): 1:30 (15%)
  • Development time (based on marked 1st): 2:17 (22%)
  • Weight loss: 50g → 42.1g 15.8% loss
  • Colortrack (WB-GR): 62.27-64.58 Δ -2.31
  • Notes: 1st crack marked at about 391°F

Profile #3

  • Total roast time: 11:00
  • Development time (based on 400F): 2:00 (18%)
  • Development time (based on marked 1st): 2:58 (27%)
  • Weight loss: 50g → 41.6g 16.6% loss
  • Colortrack (WB-GR): 63.54-65.49 Δ -1.95
  • Notes: 1st crack marked at about 390°F

Quantitative Comparison (Roast #1 → #2 → #3)

  • Total roast time: 10:00 → 10:30 → 11:00
  • Development time (based on 400°F): 1:00 → 1:30 → 2:00
  • Development time (based on 400°F): 10% → 15% → 18%
  • Development time (based on marked 1st): 0:47** → 2:17 → 2:58
  • Development time (based on marked 1st): 8%** → 22% → 27%
  • Weight loss: 15.6% → 15.8% → 16.6%
  • Colortrack (WB): 62.26 → 62.27 → 63.54
  • Colortrack (GR): 62.77 → 64.58 → 65.49
  • Colortrack (Δ): -0.51 → -2.31 → -1.95

Qualitative Comparison

  1. A little juicy, with a little acidity hidden in there. Flavors quite flat and indistinct. Drinkable.
  2. Slight burnt taste, very flat. Little or no noticeable acidity.
  3. Darker flavors, strange unpleasant aftertaste. Flat flavors, no acidity. Not very drinkable.

Conclusion

I believe I learned what happens when you take the roast too far! The starting point for this test was already too far along, so that will need to be adjusted to find a more reasonable starting place. I have plenty of this green coffee, so I will run a few more test cycles to see if I can generate a meaningful results. For test 2, I am going to find a profile that produces a good drinkable roast and then try tweaking the development.