Home Coffee Roasting: How to Choose Your Coffee Beans

Interest in home coffee roasting has grown significantly in recent years. Brewing coffee from beans you’ve roasted yourself brings a unique flavor and adds a touch of sophistication to daily life. Once you’ve acquired a decent home roaster and done your research on roasting techniques—through books, articles, or videos—you’re ready to put your skills to the test. However, there’s a major hurdle you’ll need to overcome first: selecting the right green coffee beans.

As a home-roasting enthusiast, you’ll want to pick beans that bring out their best flavor characteristics once roasted, and then brew them in your preferred method. You might even share your home-roasted beans with lucky friends and family. Yet, shopping for green beans can be intimidating. How do you find a coffee that suits your taste? Below are a few simple tips to help you distinguish between different green coffees and pick one that matches your preferences.

Not All Green Coffee Beans Are Alike

Brazil or Ethiopia? Washed or Natural? Arabica or Typica? Green coffee beans differ in many ways—factors that influence not just the flavor but also how you should roast them. Here are some key considerations:

1.     Origin (產地)
This refers to the environment where the coffee is grown—climate, humidity, soil conditions, and more. All these factors affect the aroma and flavor of the coffee. Start by narrowing your choices from a broader region to a more specific one. Before comparing individual farms or lots, first compare beans from different countries or different regions.

2.     Variety (品種)
Coffee has both “species” and “varieties.” The variety, which is a subset of a species, can drastically impact flavor. Tasting Yellow Bourbon, SL-28, or Geisha can each provide a distinct sensory experience.

3.     Altitude (海拔)
Generally speaking, higher altitudes mean cooler temperatures, which slow down the growth of coffee cherries. This often leads to sweeter fruit development. As a result, coffee grown at higher altitudes tends to offer richer flavors, more sweetness, and often more vibrant acidity compared to lower-altitude beans.

However, remember that temperature varies from one region to another. For example, in Hawaii, growing coffee above 600 meters can be too cold, yet Kona coffee is still quite famous. In Ecuador’s Galapagos Islands, coffee grown at just 200 meters can be classified as specialty coffee. These variations must be taken into account when assessing the altitude of coffees, especially from different countries or continents.

4.     Processing Method (生豆處理法)
How are the coffee beans extracted from the cherry?

• Natural (Dry) Process: The whole coffee cherry is dried in the sun before the outer fruit layer is removed. This typically results in sweeter beans with pronounced fruity flavors.
• Washed (Wet) Process: The fruit layer is removed before drying, which usually yields cleaner flavors and a brighter acidity, though with less sweetness compared to natural process.
• Honey Process: Part of the mucilage (the sticky fruit layer) is left on the bean while it is dried. Honey-processed coffees generally have more sweetness and a fuller body than washed coffees.

In addition to these three common methods, you may encounter other specialized processes like Monsooned coffee, Wet-Hulled coffee, or experimental fermentation methods. These are often tied to specific regions—for instance, monsooned coffee is stored in warehouses during India’s humid monsoon season.

By understanding the factors above—origin, variety, altitude, and processing method—you can more easily identify green coffees that align with your taste preferences and roasting goals.