While working as a professional coffee taster and quality controller with several of the top coffee companies in Kenya, cupping hundreds of coffees every day for many, many years, I found that certain physical characteristics in the formation of the green beans consistently produced very specific and identifiable qualities in the profile of the resulting roast.

In this article we are going to share our experiences as to how these various flaws in the physical formation of green coffee beans can help you understand the cause of resulting cup and, therefore, help you with your green bean purchases.

There are many factors within the various stages of plant husbandry and harvesting that cause these flaws in green bean formation which we’ll identify in this article. More important, we’ll speak to how these formation flaws can directly affect cup acidity, body and flavor.

To begin, the major formation flaws found in green coffee beans prior to roasting include:

o Shriveled

o Thin edged

o Boat shaped

o Ragged

o Hollow or Shell

o Multiple center cut

Since a number of these formation flaws tend to occur together in the same beans, we’re going to group those flaws that have a similar cause and effect.

Shriveled, Thin Edged and Boat Shaped

Green beans that are shriveled are deformed beans, usually small, irregular or immature in formation, usually with multiple center cut. Thin edged and boat shaped are easily identified as the name of the flaw indicates.

Beans with these formations are lacking in nutrition, including Chlorogenic acid and magnesium during the growth process. Causes also include drought or lack of sufficient irrigation. As a result, these beans will normally be whitish to brownish-yellow in color.

The beans will sometimes open during roasting and almost always produce a soft roast. In addition, these flaws in formation often cause the beans to break during the roasting and blending process.

As a result, the roasted beans will tend to give you a smoky taste because they require over roasting, compensating for the pale beans. More often than not, they will also have excessive hay and grassy flavors.

During cupping, you’ll also experience a flat cup, a harsh full body and lacking in acidity. The excessive presence of shriveled beans will result in a high percentage of moisture loss (20% plus) during roasting.

Ragged

These beans are not smooth, but instead have a rough and corrugated appearance. This is caused by overbearing, drought-affected cherries and immature in ripening, often leading to a yellow cherry. You’ll notice that these beans will also have a sticky sliver skin which isn’t completely removed during the milling process.

Roasted ragged beans will result in a pale color with a lot of chaff, partially because of the sticky silver skin. The result will be a soft roast which is more permeable and, together with the chaff, will result in very fine fragments in the brewed coffee, giving a heavy and viscous body in the cup with many impurities.

Hollow or Shell

This formation flaw is sometimes caused by deficiencies in minerals in the soil, but with a generous water supply, causing the tree to produce large beans that mutate. This condition can also be caused when two beans are growing together and then one dies while the other continues to grow, which are commonly referred to as shells because of the resulting formation.

The roast of hollow or shell beans is very similar to that found with shriveled, thin edged and boat shaped beans as described above.

Multiple Center Cuts

These beans are identified by having two or more center lines. This formation is usually found in shriveled beans and ragged beans, but can also be found in full solid beans. The causes range from either overfeeding or because the coffee trees have been drought affected.

Still, too many multiple center cuts, all other things being acceptable, will cause an uneven grind after the roast, negatively affecting the body in the cup.

Conclusions

High quality beans will not contain formation flaws, whereas most coffee beans that do contain these types of flaws will remain pale and under roasted at a normal roast. As a result, beans with these flaws require over roasting which will result in a high percentage loss in total weight of 20% or more. This loss in weight should be taken into account when buying green coffee and measured against high quality alternatives.

Over the years, we’ve found that green bean quality and its resulting cup is not a result or origin, but primarily a result of superior plant husbandry, milling, grading and sorting, enabling each country to produce top quality coffees with ideal characteristics for that region.

This article is the second in a five-part series describing general guidelines on how to determine quality characteristics of green coffee beans before the cupping analysis.