Updated: May 27, 2019
How dark is too dark? roasting coffee is very much a matter of finding the level that you prefer in all the infinite shades of grey (or brown) that exist!.
In my time as a coffee roaster, these are the two questions I usually start with,
what are the origin characteristics? and what do i want to highlight so that i can enjoy the best of this coffee?
The next step is understanding what roast level brings out the desired flavours. you will find that light and delicate flavours exist at lighter roasts, and heavier and more complex flavours exist at more developed roasts.
Heres a quick basic guide to when to end the roast:
First crack: very light flavours, vegetal corn and nut. maybe some fruits
First Crack + 1 minute: bright acidity, some caramels, fruit and florals
First crack + 2 minutes: medium acidity, complex caramels, ripe fruits and milk chocolate
First crack + 3 minutes: low-medium acidity, heavy body, dark chocolate, dark fruits
***DISCLAIMER*** bear in mind your roasting system, speed of roast and end temperatures will all play a factor in how 'developed' your roast tastes.