Have you ever wondered just what goes into coffee roasting? Here’s a simple explanation!
What happens when coffee is roasted?
Coffee arrives at our roastery green, or unroasted. When we put it in the roaster, a predictable process happens. As we apply heat, the bean changes color from a gray/green to yellow to brown. If you were in the roastery while we do this, you would notice the smell change from grassy to wheaty to well, roasty. This change to a brown color is the Maillard Reaction, and it happens when you cook (or brown) anything. Simple sugars and amino acids break down and reform, giving the food that cooked and barely sweet flavor. The same thing happens to coffee beans.
First Crack
As the beans continue to cook and their color gets darker, they also start to expand a little. Soon they reach what is called ‘first crack’. During first crack, the beans rapidly release any remaining water as steam and this makes the cracking sound. At this time, the beans will also start to release chaff. First crack sounds a lot like popcorn popping.
Sometimes a roast may be done around first crack (we’ll get to that soon), but often, the beans continue roasting. This is the development stage, and it’s when certain flavors in the bean become more or less prominent depending on how long they roast. The beans will also continue to darken.
Second Crack
The beans will then move into ‘second crack’ which sounds a little smaller or higher pitched than first crack. During second crack, the cellulose and structure of the bean get more and more brittle. Pressure from carbon dioxide inside the bean builds and then cracks the structure to release. During second crack, oils and gasses can move to the surface of the bean, creating the oily look of dark roasts. After second crack, the roaster decides just how dark they want their dark roast before dropping the roast in the cooling tray to stop the cooking and development.
Up next, we’ll be looking at the flavor differences between different roast levels.
Time to reorder? Check out our roasts here!