1. Roasting Process

• Temperature and Time: Dark roasts are roasted at higher temperatures, usually between 430°F and 480°F (221°C to 249°C). The roasting process continues beyond the first crack and into the second crack, which happens at higher temperatures. The second crack is when the structure of the bean starts to break down more dramatically, releasing oils and causing the beans to darken.
• Roast Stages: Dark roasts typically begin after the first crack and continue until the second crack is heard, or sometimes even beyond that. The roast level can range from "Full City" (a medium-dark roast) to "Espresso" or "French Roast" (darker roasts).

2. Flavor Profile

• Smoky, Bitter, and Charred: Dark roast coffee typically has a robust, smoky flavor due to the breakdown of sugars and the caramelization process that occurs during roasting. As the roasting time increases, the coffee's natural flavors are overshadowed by these roasted, slightly bitter flavors.
• Low Acidity: One of the hallmark characteristics of dark roast coffee is the low acidity. Unlike light and medium roasts, dark roasts have minimal bright or fruity notes, making them less tangy and more mellow. The longer roasting process reduces the levels of acids in the coffee beans.
• Bitter and Toasty Notes: Dark roasts often carry a bitter or slightly burnt taste, especially if they are roasted to the very dark end of the spectrum. This can give way to toasted or burnt sugar, caramelized flavors, or even a slightly chocolatey finish. However, excessive roasting can lead to over-carbonization, which can make the coffee taste excessively bitter or even ashy.
• Lack of Origin Character: The roasting process at higher temperatures tends to overpower the unique flavors that might come from the coffee's origin (such as fruity, floral, or earthy notes). Instead, dark roasts tend to emphasize roasted flavors rather than the nuances of the beans’ region, variety, or processing method.