What is scorched coffee?
Scorched coffee is burnt on the outside but still underdeveloped inside. It usually happens when the drum is too hot and turning too slowly, causing the beans to sit against the hot surface and burn before they’ve roasted through. The result is a mix of smoky, bitter, ashy flavours with grassy or hay-like notes from the still-green centre.
How can you prevent scorching?
You can prevent scorching by lowering the charge temperature and increasing airflow or drum speed slightly - just not too much, or the beans will get pushed to the edges of the drum and scorch again.