What is charge temperature in coffee roasting?

Charge temperature is the temperature your drum has stabilised at before you load the green coffee. It's the starting point of the roast - and it has a disproportionate influence on everything that follows.

When cold green beans hit a hot drum, the temperature drops sharply. That drop is the turning point. How quickly the beans recover from it, and how much heat they absorb in the critical first few minutes of the roast, is directly shaped by your charge temperature. A higher charge means more heat transferred early on; a lower charge means a gentler, slower start. Charge too high and you risk scorching; charge too low and the roast can struggle to build momentum.

Every roaster has a target charge temperature for each profile, and it needs to be consistent to get consistent results. Seasonal variation, batch size differences, and even how long the machine has been running all affect where you actually land. Logging it - not just setting it - is what makes a profile reproducible.