WCRC Taipei Roast Profile
This blog post may contain many technical words.
And profile written on this blog is not a recommendation.
Please do your own research.
I had the pleasure to participate in the world coffee roasting championship 2019 in Taipei.
This competition challenged me in every aspect of the coffee chain from green bean to roasting, blending to cupping (tasting).
I came 15th overall. No need to say I was disappointed with the results, but I was still very happy with my performance. After all, it's not that bad to be in the world top 15 coffee roasters ; )
The rules are similar to the National competition and you can find all the details in this previous posts if you are interested.
Here, I would like to share my profile and theory I used in the world stage.
Roaster: Giesen W6A
We were only given 40 minutes to practice in the production roaster. I decided to use the highest airflow (180Pa), 41Hz (61RPM) drum speed, and 2kg batch size.
Using a small batch size and high airflow means that I can better utilise the convection heat (Heated Air) rather than conduction heat (Direct heat from the drum). In theory, I could fully control the roast profile with the right gas adjustment based on exhaust temperature RoR (rate of rise).
The competition roaster Giesen W6A is amazing at developing the coffee from the momentum energy stored in thick cast iron drum. I struggled to control the energy and stabilize the starting drum temperature. During the practice roast, I pulled off 2 batches. None of them were good profiles, but I got enough data to come up with a better roast profile for the competition roast.
We didn't get any information about this coffee, but looking at the screen size and flavor notes from the samples roast, it was undoubtedly a Kenya AA.
- Origin: Kenya AA (assumed)
- Moisture: 10.3%
- Density: 830g/l
- Start Temperature: 190C
- End Temperature: 198C
- Development time: 1:35
- Color: 84
- Start weight: 2000g
- End weight: 1840g
I charged at 190C and 80% Gas setting to create a high Delta T (Temperature difference between beans and drum), to ensure an efficient heat transfer.
I decreased the gas setting gradually to match the bean RoR (rate of rise curve) and exhaust temperature for my profile.
In this case, bean RoR 5.5C/30secs when I hit 1st crack at 185C to reach 198C in 1min35secs as per my roast plan.
The first roast wasn't too bad, but I didn't hit the end temperature to my plan.
In my 2nd attempt, I hit all the numbers following my roast plan.
My prediction on this roast was very light and fully developed. I wanted to accentuate the Kenyan acidity and sweetness while keeping it well balanced from the full development.
What the judges say?
- Aroma: 7-7.5 Lemon, nutty
- Flavor: 7-7.25 Cane sugar, Lime, Caramel
- Aftertaste: 6.5-7 Tanning, dry, astringent
- Acidity: 6.75-7.25 Lemon, plum, malic
- Body: 6.5-7 Thin, tea-like
- Sweetness: 6.75-7.25 Cane sugar, mellow
- Balance: 6.75-7 Not complex, unbalanced
Oh well, that's not what I wanted to achieve...
What I could have done differently?
When I look at this profile now, I feel that the exhaust temperature is a bit too high and the total roast length maybe too quick. If I could do it again, I would use a lower charge temperature or lower gas setting to extend the roast length and keep the bean RoR curve to be slightly lower. The end temperature could be 196-197C.
In short, longer roast length, and gentler heat.
I would also spend some time experimenting with different drum pressures. I had seen most of the competitors used 100-120Pa. I have yet to fully understand the effect of the drum pressure to the cup quality in this roaster.
When I blind cupped all the competitor's coffee, none of the single-origin roast showed sparkly bright acidity. More than half of the coffees were rather dark and showed roasty aftertaste.
I would have liked to taste my sample production roast so that I could have adjusted my roast curve. Having said that, we were all on the same page. Hats off to all the competitors, especially the top 3 winners achieving the best tasting profile in this tough condition.
Please check out the profiles from the top 3 here.
I would love to know their approach in detail.