This article is the first in a five-part series describing general guidelines on how to determine quality characteristics of green beans before the cupping analysis.
There are many factors within the stage of picking, drying, milling and grading that can affect the outcome of green bean color, and also the quality. The phenomenon can as well affect the cup acidity, body and flavor. In this article we are going to focus specifically on the color of the raw beans after they are processed, graded and ready for roasting. The major colors found in caffeinated green beans include
Grayish-blue, This is the most highly desirable color found in the high quality coffee beans. The latter is obtained by means of sun drying after washing. Along the process of sun drying the coffee is allowed to receive the heat in a gradual way, while the coffee beans are set on a drying table and the air is allowed to percolate around the beans in an even manner. The parchment coffees which generally produce a grayish blue color are normally found intact and whole, hence free from any split and open defective beans after the drying process. The moisture content of these types of beans ranges from 8.5% to 10.5%, in both parchment form and after the hulling. After hulling and grading, coffee beans retained on screens 16, 18 and 21 are coffees of high density and strictly hard beans and reflect a white center cut in every stage of the roasting profile. At a medium roast, beans with these characteristics will produce a darkish chocolate color (without over roasting), and slightly shiny without an oily exterior (often caused by over roasting). This is the ideal. Properly dried beans of a grayish-blue color will give a well balanced acidity, full body and a rich flavor free from any aftertaste.Rapid coffee drying will give a parchment that splits open in the final drying process. The same process will also affect the grain, creating a brownish tinge around the edges. In addition, some of the beans will fade, resulting in a whitish to yellowish color and light in density. In the final analysis rapidly dried coffees have characteristics of light acidity to somewhat lacking acidity, light body and a flat flavor in the cup. Typically, you'll find some variation of color in any coffee lot and the final analysis during cupping will always determine the best fit for your specific use.
Grayish-Green, This is another category of coffee beans which are normally found to be fairly solid in formation, and high density. Grayish-green beans are usually well dried and free from open parchment.Beans with these characteristics are commonly found within the coffees that come from South America, Central America, Papua New Guinea and Hawaii. Grayish-green beans at the medium roast profile will produce a brilliant chocolate color. The cup analysis will normally reflect a rich and smooth acidity, heavy body and a mellow flavor.
Brownish-gray-green, Brownish-green, and Brown washed green beans which reflect a brownish-gray-green to brown color are the coffees which usually have been picked either at stages of under ripe or over ripe. This color is also formed by scorching heat during sun or mechanical drying, over fermentation. Old warehoused coffee is another factor that can contribute to this type of color variation. Beans of this type of will generally produce a very light acidity, light body and, normally, overly dominant flavors which can include any combination of: woody, earthy, fermented, nutty, slightly harsh, bitter, greenish, grassy, potato and medicinal. These characteristics are often masked by a very dark roast to add body and deaden strong undesirable flavors.
Keep in mind that there are other criteria of green beans that can also contribute in varying degrees to the characteristics of acidity, aroma and flavor, including: bean formation, center cut, moisture content and defects. We will be discussing each of these criteria in our upcoming articles.