top of page
coffee roasting machine

Coffee Bean Science with coffee roaster

Updated: Oct 16, 2023

rostino coffee roaster

When you roast green coffee beans with your coffee roaster, their color, not surprisingly, begins to change. The bean, which starts off anywhere from steel gray to pea green, fades first, as its green chlorophyll breaks down. Then, as the Maillard reaction kicks in, the bean starts to turn yellow, then tan, then deeper and deeper brown. The Maillard reaction, which develops flavor as well as color, is responsible for the delicious hue of very many of our favorite brown foods, from grilled steak to crusty bread to dark, malty beer. Amino acids and sugars in the coffee interact in a complicated cascade of reactions, producing hundreds of flavor compounds and compounds called melanoidins, which give coffee its brown color. As the beans continue to get hotter, caramelization happens as well. While the Maillard reaction happens between sugars and amino acids, caramelization involves sugar alone. The main sugar present in green coffee is sucrose, which doesn’t partake in the Maillard reaction. Instead, the sucrose caramelizes, breaking down and yielding additional brown compounds. If roasting continues further, the brown color will edge toward black, as sugars and cellulose begin to break down into carbon. Color is not all that changes. As coffee roasts, it loses mass. The darker a coffee is roasted, the more it loses: water exits the bean in the form of vapor, and so do carbon dioxide, free nitrogen, and volatile compounds. A batch will typically lose 10 to 20 percent of its starting mass during roasting. At the same time, each bean can double in volume, due to the puffing when the vapor escapes.

Get offer for advanced coffee roasting machine over email or whatsapp :


6 views0 comments


bottom of page