How To Roast Green Coffee At Home

Coffee is a small red fruit that must go through many stages to become the tasty brown bean we all know as coffee. Most good coffee is first wet processed to remove the outer skin, pulp (which is actually fermented away), and inner parchment skin. Then the inner seed, or bean, is dried and becomes the green coffee that is shipped and stored around the world. Green coffee is a lot like a dry pinto bean- it can be stored for a long time yet still become a fresh and aromatic food item after it is roasted or cooked.

The final step to make the coffee bean ready for brewing coffee is to roast the green beans. Without roasting, a beverage made from the green coffee bean would be bitter and extremely acidic- in short, undrinkable. The relatively simple act of roasting coffee used to be a common home task, but it todays modern society it became shrouded in mystery as the process was taken over by large companies in the late 1800’s. The growing popularity of gourmet coffee has sparked an interest in reviving the traditions of roasting coffee at home. Fortunately, today we have the advantages of modern knowledge and devices to make coffee roasting easier than it was over a century ago.

Green (unroasted) coffee beans

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During the roasting process the green coffee changes dramatically. The process of roasting forces water out of the bean, causing it to dry and expand in the process. Some of the natural sugars in the bean are transformed into CO2 gas, and others are caramelized into the complex flavor essences that make a good coffee. The colors darken and at the end of roasting the bean is about 18 % lighter in weight and 50 to 100% larger than when it was green. After roasting the coffee continues to “degas”, emitting CO2 which helps protect the delicate flavor and aroma of the coffee. Just one week from the time it is roasted, the coffee has already started to lose some of its best flavor and aroma- the best reason to roast your own!

Learn more about roasting your own coffee at home.