Coffee Sojourn in the American Northwest: Portland, OR - Part 4 (Drying methods and cupping)

Day 2 - Second Topic

Following two rounds of enzyme cuppings, the presentation shifted to the topic of drying methods. We would be showcasing three different methods, and cupping each in order to determine again, the extent of the influence that method played in the final cup quality. 

 

Coffee Drying

Regardless of method, coffee drying is the process of permitted the coffee to develop from an approximate 60% internal moisture content, to one of 11%, give or take a percentage. 

 

Why 11% Moisture

It is widely accepted that coffee reaches its highest quality, when permitted to dry and rest. The 11% moisture level is simply the point at which coffee contains little enough moisture, to make it less susceptible to fungus, bacteria, etc; and enough moisture to keep it from shattering or breaking when going through the hulling process; and therefore is the target percentage within the industry. 

11% is, in practicality, more for the miller than it is for the roaster. 

 

Methods

In order to reach this target percentage however, multiple methods are used. While others exist, the ones used at Beneficio El Manzano are as follows: 1. Patio 2. Raised Beds 3. Mechanical Dryers

 

Patio

Patio drying is the method in which coffees are spread onto tiles.  Traditionally, coffees on a patio are stirred once every hour; and are dried, from the air passing over and through them as they are stirred and exposed, and from the heat of the suns direct contact with both the bean and patio. As coffees are raked, they are positioned onto new portions of the patio, that had previously been exposed to the sun, and thereby heat the bean, allowing it to dry. 

 

Raised Beds

Raised beds are a similar method, however, since coffees rest on a screen, raised above the ground, they are less influenced by the heat generated from the patio, and more so by airflow, which passes both above and through the screen, and thereby over the bean. The common thought is that, because of airflow, coffees on a raised bed dry more quickly, however, in our observation, they in fact dry at a slower rate than coffees on the patio. Despite drying from sunlight, the screen on which they rest does not generate the same amount of heat as the tile patios, and therefore keep the coffees at a reduced temperature, causing them to dry at a slower rate. 

 

The Experiment - Patios vs. Raised Beds

Throughout the harvest, we had been using the raised beds for drying various coffees, however, we were interested in measuring the differences between the patio and raised beds, drying the same wet parchment side by side. 

On February 15, we began the experiment with Finca El Naranjo, placing half of the washed parchment on the patios, and the other half on the African bed. We hoped to measure both the rate at which the coffees dried, and the final cup quality produced by each of the different methods. 

Within measuring and monitoring the coffees, we began to notice a difference in the speed at which both coffees dried, and the temperatures at which they did so. 

Coffee on the patio dried at a consistently higher temperature, and lost its external moisture much faster than coffee on the beds. Also, the coffee on the patio required a smaller number of days to complete the process, finishing by the end of the seventh day of drying, while the beds required a total of nine days. 

Finally, in observing the green coffee, we noticed the coffee from the beds to contain a much healthier, bluish color, while the green coffee from the patio, although healthy and well taken care of, appeared a paler shade of green. From this, it would almost seem as if the beds enable coffee to dry at such a rate, that it is not damaged from the direct sunlight that it receives, whereas, the coffee on the patios, in its faster pace, could be more susceptible to being dehydrated from the sun. 

 

Mechanical Dryers

Mechanical dryers are controlled drying, where coffees can be given airflow, heat, and agitation within a consistent and controlled environment. Since they are not dependent on sunlight, they can be run over the course of the night, and thereby enable coffees to be dried much more quickly and efficiently. 

Once finishing the explanations of each of the drying methods, we moved back into the cupping room, and allowed the audience to try each of the drying methods, performed on the same coffees. Over the course of the harvest, we had divided batches in half and thirds, and put them through each of the various drying methods; thereby enabling us to measure the influence that method played in the final cup. 

Our primary interest is in what others thought of the final cup quality on the table, and after hearing feedback, discovered that in the case of Raised Bed vs. Patio, members of our audience preferred the raised bed; and in the case of Patio vs. Guardiolla, members of our audience unanimously chose the Guardiolla. 

Drawing conclusions from these results is difficult, since the subjectivity within cupping, and varied weather within the entire coffee process prevents a perfectly equal foundation for comparing coffees under different conditions, however, we can begin to note specific reasons why different methods produce different levels of quality, considering the conditions which those methods develop the coffees. 

To be continued: The I-5 to Seattle, Dillanos Roasters & Atlas Importers.