Scorching and tipping causes

Understand why scorching and tipping occur during roasting and how to prevent them.

Article 1 of 12 in Roast Defects & Troubleshooting/

Key Concepts

Scorching:
Caused by excessive heat at the start of the roast or poor heat distribution.
Often seen as dark spots on the flat surface of the bean.
Can result from too high charge temperature or prolonged contact with a hot drum.
Tipping:
Occurs when the tips of the beans are over-roasted while the rest of the bean is underdeveloped.
Commonly caused by high heat flux, rapid airflow, or incorrect drum speed.
Prevention Strategies:
Optimize charge temperature according to bean density.
Ensure uniform heat transfer and adequate drum rotation.
Adjust airflow to prevent localized hotspots.
Monitor Rate of Rise (RoR) to avoid sudden temperature spikes.
Troubleshooting:
If scorching appears early, reduce initial heat and check drum contact points.
If tipping occurs, reduce airflow or spread beans more evenly in the drum.
Conduct sample roasts to calibrate settings for specific lots.

Proper control of heat, airflow, and drum dynamics prevents scorching and tipping, ensuring even roast color and flavor development.