Dark roast coffee seems to have many more aliases than the other roasts. They are commonly referred to as “Continental, European, Espresso, Viennese, French,” and the list goes on. If you examine dark-roast beans, you will notice a consistent oily surface spread throughout the batch. Going along with the steak reference, you will always taste part of the roasting process itself by drinking a dark roast coffee. It will lack acidity, but provide smoky, charred flavors that many consumers are seeking.
After roasting, there is a gassing off period for coffee beans. This process can take anywhere from 1-10 days to complete, depending on roast color. Dark roasted beans take longer to gas off than lighter roasts. During this time, carbon dioxide and other trace gasses are released from the bean. If you’ve ever ground and brewed coffee fresh out of the roaster, you’ve likely experienced an overflow of grounds inside of the filter basket. This is caused by a reaction between the hot water and trace gasses within the coffee.
