That beautiful city roast

[canadaroaster]

Hey Guys,

I've been trying to get to roast a dense Yemeni coffee for a while now to an even roast medium roast that a contract roaster did for me a while back but to no avail, I either get uneven roast with patchy darker stains and it tastes acidic but not sweet. If I roast longer I get darker colour and even in colour but burnt taste starts taking hold. how do you do it? I am looking for that city roast that has a crisp surface of brown and uniform colour.

I used last 330 g
dropped at 185C
TP at 2:00min,
FC at 8:00min
dropped at 10:00min

I also don't have a variac so I adjust the valve increasing the airflow about half way through the roast.

Any tips?

[edtbjon]

Try to find something cheaper for controlling the fan. Some kind of router controller will do nicely. Then you find three settings like described in the MillCityRoasters video.
From your times I guess that you don't use any heat until TP. (Else you'd get your TP within 1.30 or so...) Try lowering the charge temp a bit to 160-170C and turn on full heat at around the 1 minute mark. If you try to get a bit longer midphase (Maillard), the roast will be more "even", even though I guess the Yemeni coffee behaves much like e.g Ethiopian coffees, in that most Ethiopians I've roasted usually never look as uniform as e.g Central Americans. (I never got hold of any good Yemeni coffee, but I'm still looking for it. )
One trick to make roasts a bit more uniform is to prolong the first drying phase a bit. I usually do that by charging at a lower temp, so that I can give the beans more energy throughout the roast.
For keeping sweetness but burning off a bit of acidity, while keeping it a light roast, you really need to go into the 1C at the very right RoR, else you will either bake the coffee or rush through the last phase too quick with high acidity or too dark coffee as the result. This is the tricky bit to "master" which comes with experience.
Finally, all the parts of the roasts are dependent on the previous part. I.e the last phase depends on hitting the right "speed" in the previous part, and so on back to the charge temp and when you turn on the heat. This takes knowing the roaster, the coffee and the theory about roasting.

[Gregr]

Having roasted a bunch of Yemens with the Huky I can confirm a long drying phase is a good idea. Also- Yemens are notorious for roasting unevenly and you'll often see people say you should embrace that. A good way to get evenly roasted beans (with all beans really) is to try using the fan at a moderately low setting for most of your roast. Good airflow insures the beans get evenly heated.
Yemens are also notorious for having rocks unintentionally mixed in with the beans so it's wise to check before you put them in the grinder.  Another thing about Yemens is they're going to taste a lot better after a week's rest- like most Sumatras.
Based on comments by people like Rob Hoos, you can mute the brightness by extending the middle phase- maybe more like 4:30-4:45 should be enough. Unfortunately you will aslo mute some of the fruit notes, but hopefully not too much. Going long on the last phase will also mute the brightness but since you're aiming for a city roast you'll want to be dropping the beans at the end of first crack roughly-- that is going to be tricky and has a good chance of tasting grassy even after a good rest. Personally, I'd opt for a 4 minute middle phase and 2:30 or so development, but that's just a recipe that I like a lot for espresso and often works very well for pour over too. It's not city- more like fc- with a finish temp around 214C. It tends to preserve those origin fruit notes, retain a nice amount of brightness and keeps enough moisture left in the beans for a decent amount of development so the bean temp doesn't shoot thru the roof.