La Luna Dry Mill

La Luna is the name of Agricafe’s dry mill that is located in Kañuma, about halfway between the city of La Paz and El Alto. The mill sits at a staggering 3,800m above sea level, making it one of the highest (if not the highest!) dry mills in the world.

The plant is located about 20 minutes drive from El Alto airport. The roads are very steep and a little dangerous with deep gutters and sharp corners. Along the way, there are many street vendors, who sell everything from small individual candy, to bags of peanuts, and plastic bags of fresh fruit juice. There are also a huge amount of vendors selling building supplies to support the rapid growth that the towns of El Alto and La Paz are currently experiencing.

The drive down to the mill has amazing views of the surrounding mountains. La Paz sits in somewhat of a valley (despite being at 3,600m above sea level), surrounded on one side by the vast tablelands of the Altiplano Plateau and the other side by the Cordillera Real, a mountain range that sits between La Paz and the Amazon basin where the coffee is grown. The view from the mill is spectacular and gives a great perspective on La Paz and how it sits among the surrounding ranges. Due to its elevation, there is very little greenery nearby, walking up to La Luna truly makes you feel like you have arrived on the Moon.

The mill’s premises, as well as most of the processing equipment inside, are kept in pristine condition. The building also houses Agricafe’s export offices, and includes a cupping lab and meeting room, both with spectacular views of the surrounding area.

A total of 20 permanent staff run La Luna year-round. Operations at La Luna have been managed by Efraín Arrata since 2012, after previously being in charge of a parchment warehouse Agricafe kept. Efraín, who told us he is motivated by pressures that arise during the harvest, enjoys working at La Luna because it allows him to “contribute to a high quality, competitive product.” To do this, he is assisted by Victoria Durán, known affectionately as Vicky, who serves as the mill’s QC manager. Durán started working at the dry mill in 2014, and has been roasting and evaluating lots since 2018.

During the peak of the season, the mill receives some three truckloads of coffee parchment or pods per week, which reduces to one per week during quieter periods. The site can process up to six tonnes of parchment per day, and though the equipment has capacity for more, the human labour — which is key to the high quality Agricafe is known for — slows operations down.

HOW THE COFFEE IS PROCESSED:

First, as the coffee arrives having already been tagged and labeled at the wet mill, lot details are checked to ensure they correspond with the lot they are expecting. To ensure traceability is kept at every step of the way, each individual lot keeps the same code it receives during cherry delivery through to export. 

On arrival, all parchment is weighed, and its moisture percentage checked. The parchment is then loaded into the first screening machine, which essentially ‘cleans’ the coffee by removing all sticks, stones and remaining foreign matter. This machine has two large vibrating screens, the first that allows only coffee beans to fall through (up to screen size 25), effectively sorting everything larger than coffee beans out. The second screen sits below the first one, and removes everything that is smaller than coffee beans (down to screen size 14), allowing no dirt or stones to filter through.

In the second stage, the coffee is hulled in a machine made by Pacific, which basically rubs the coffee in parchment together, using friction to loosen the parchment off the beans. In the third stage, the coffee is sorted by size. Efraín’s team the same screening machine that starts the milling process, but this time the screen sizes are much more finely tuned, allowing only coffee that is between size 14 and 18 to pass through to the next stage.

In the fourth stage, the coffee is sorted by density by using a vibrating table that separates the very light beans (unripes, etc.) out of the lot of coffee. From this stage the seconds, or the rejected beans, go through a second density sorting machine that recovers any dense, or firsts, and feeds them back to the main lot. 

In the fifth stage there is an electronic laser colour sorting machine. This is a 15 channel machine, which very quickly takes photos of every bean that falls down the channel, and rejects beans based on a set of pre-determined parameters. Because the machine can be fine tuned repeatedly, it can reject anything from full black to sour beans, and anything that is slightly outside of the specified colour range, without removing beans that have changed colours as part of processing. These colour sorting machines are great for quality because they are extremely efficient. In places like Rwanda, this work is typically done by hand, while in countries like Brazil, it is more common to see a laser sorter being used.

The last two stages are all about hand sorting. The mill employs 8-10 seasonal workers to hand pick over the coffee from conveyor belts, because as Efraín told us, “no machine is as good as the human eye.” The first round is done in a dark room, lit only by an ultraviolet light, which is key because it highlights any beans that are affected by a number of defects, like higher moisture content, mould, bacteria, and even chip marks from the de-hulling machine. Once the coffee has gone through the UV sorting, it goes through a second pass under natural light. Coffees are then assessed, and depending on results, either sent back to be re-sorted, or placed in silos to prepare bags for export.

Around 40% of Agricafe’s exports are vacuum-packed, a number that has continued to increase over the last four years. This is partly because the company has placed greater focus on more differentiated nano lots, but also because their market as become more demanding of quality. While this does create somewhat of a bottleneck, the end result is of such exceptional quality, that the Rodríguez family and their customers (ourselves included!) are willing to wait as long as it takes.