Charge Temperature
Charge Temperature is the temperature of the roasting drum immediately before green coffee beans are introduced. In other words, it’s the initial temperature of the roasting machine at the start of the roasting process.
The charge temperature directly affects the initial heating rate of the coffee beans, which in turn impacts flavor development and color. A charge temperature that is too high can cause scorching of the coffee beans, resulting in bitter and smoky flavors, while a temperature that is too low can lead to uneven coffee development and a bland flavor.
According to Danilo Lodi, an expert from Dalla Corte and a judge at the World Barista Championship, the input temperature when roasting coffee depends on the bean density and processing method. Hard, dense coffee beans require a higher temperature than soft, porous beans. Naturally processed coffees, due to their high sugar content, are more prone to burning and therefore require a lower charge temperature compared to washed coffees.