What is charge temperature?
Charge temperature is the stable temperature the roaster is heated to before any coffee is added. It’s the starting point of the roast, and it sets the tone for how heat will transfer into the beans. Since roasting is all about managing energy, charge temperature has a big impact on how the roast unfolds.
What should your charge temperature be?
If the charge is too low, the roast may stall or take too long to develop flavour. If it’s too high, the beans can scorch – burning on the outside while staying underdeveloped inside.
There’s no universal number – it depends on your machine, batch size, probe placement, and room temperature. It also depends on the coffee you’re roasting. Denser beans (often grown at higher altitudes) usually need a higher charge to penetrate the coffee bean. Natural coffees tend to do better with a lower charge to stop the higher sugar content in them from burning. Coffees with high moisture content may benefit from a slower start and lower charge to allow for a longer drying phase. And espresso roasts typically call for a higher charge than filter roasts, as they’re often taken darker.
Getting the charge right takes trial and error – it’s about understanding your setup and how different coffees respond.