Traditional German pumpernickel contains no coloring agents, instead relying on the Maillard reaction to produce its characteristic deep brown color, its sweet, dark chocolate, coffee flavor, and its earthy aroma. To achieve this, loaves are baked in long narrow lidded pans 16 to 24 hours in a low-temperature, about , steam-filled oven. Like French sandwich bread, or a pullman loaf, Westphalian pumpernickel has little or no crust. It is very similar to rye "Vollkornbrot", a dense rye bread with large amounts of whole grains added.