How to handle temp drop after FC

[flat_white]

Hi everybody,

the last 10 roasts, I roasted in accordance to Gregs profile for espresso roasts. It worked out very well. Thank you Gregr!
@ Gregr: Could please explain the Fan Speed Up after drying phase? Is it to get out the moisture?

To come back to the topic....  during the last 3 roasts (with 2 different beans: Peru Cenfrocafe, Thailand Doi Chang), I experienced a strong bitterness, I never had before. The only thing I changed, was reducing the heat gradually from 170°C until reaching FC. The roasts before, I started reducing from 180°C rapdily, to reach FC with around 10-13°C RoR. This could be an explanation for the stronger bitterness due to a longer maillard phase?  WHat do you think?
The other reason, could be the strong temperature drop during FC. I tried to heat up to 2.0kpa and to speed up the fan to 50 but it is still dropping quickly. How do you handle that drop? Any tips?

Here you can see the last roast profile with a Peru arabica..... I thought it doesn't look that bad, but due the bitterness, its really not the best roast I've made :-/

[LTB]

Well, indeed your curve's not bad !

Could you be more precise : what kind of bean is the Perou one, full washed, unwashed... ? How do you tested it : brasilian cupping, filter, expresso ?

Maybe you just have a too long devellopment time. 3 minutes could be a lot, and if you put 2 kpA to a "fragile" bean during the crack, I bet you'll burn it.

[flat_white]

@ LTB
It is a fully washed bean, I tasted it with brasilian cupping and espresso.
The too long development time or the high power setting is a good hint, thank you.
But when I take only 1 kpA to counteract the RoR drop, what else could I do to flaten the drop?