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