Green Bean Quality

Part I: How Green Coffee Bean "Color" Impacts the
Flavor Profile of the Roast

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Our "Roasters Tools - Green Bean Series" is a five part evaluation of how
the characteristics of green coffee beans affect the outcome of the roast.
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There are many factors within the stage of picking, drying, milling and grading that can affect the outcome of green coffee bean color and the quality of the roast. The resulting bean characteristics can directly 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.

First, the major colors found in caffeinated Arabica green beans include*:

Grayish-blue

Grayish-green

Brownish-gray-green

Brownish-green

Brown

*These colors are those typically used in international standard classification descriptions.

There are other colors found outside the acceptable range. These include blue beans which are usually the result of very high moisture content caused by under-drying and, instead of roasting, will bake, resulting in a flat cup. A yellowish color is also outside the boundaries for acceptable beans.

Grayish-Blue

This is the most desirable color found in high quality coffee beans. A grayish-blue color is obtained by means of sun drying after washing. During 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. Beans dried on a flat surface would be turned often to guarantee a gradual and even drying process.

The parchment coffees which 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 this type of bean will range from 8.5% to 10.5%, in both parchment form and after hulling.

After hulling and grading, coffee beans retained on screens 16, 18 and 21 are coffees of high density, 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.

These same beans put through a rapid drying process will give a parchment that splits open in the final drying. 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 of 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 a medium roast 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
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 and from over fermentation. Old warehoused coffee is another factor that can contribute to this type of color variation.

Beans of this type 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, medicinal, etc.

These characteristics are often masked by a very dark roast to add body and deaden strong undesirable flavors.

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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.

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