La Luna 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 dry mills (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 Altiplano 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 the altitude, there is very little greenery, and it does in many respects feel like you have arrived on ‘the moon’.

The mill building itself, as well as most of the processing equipment inside the dry mill, is all new. The building also is home to the Agricafe’s export offices, and has a cupping lab and meeting room, again with spectacular views of the surrounding area.

HOW THE COFFEE IS PROCESSED:

First, as the coffee arrives, the lot details are checked to ensure they correspond with the lot they are expecting. Then the parchment is weighed, and the moisture percentage is checked.

The parchment is then loaded into the first screening machine which essentially ‘cleans’ the parchment and ensures that only coffee is processed.  This machine has two large vibrating screens, the first that allows only coffee beans to fall through (screen size 25), effectively screening everything larger than coffee beans out. The second screen sits below the first one, and screens out everything much smaller than coffee beans (screen size 14), allowing any dirt or stones to filter through.

In the second stage, the coffee is de-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. This is basically the same machine as the first stage, but the screen sizes are much more finely tuned, allowing only coffee that is between 14 and 18 to pass through to the next stage.

In the fourth stage, the coffee is sorted by density. Again this is a vibrating table that separates the very light beans (un-ripes 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 parameters. The operator can tune this machine very well, it can reject only full black or sour beans, or any bean that is slightly outside of a colour range. These machines are great for quality because they are extremely efficient at sorting. In other places this sorting is done by hand, or not at all. In more developed countries like Brazil it is very common to see a laser sorter being used.

The last two stages involve hand hand sorting. The mill employs 8-10 seasonal workers to hand pick over the coffee from conveyor belts, the first goes through a dark room lit only with a ultraviolet light, and the second is lit normally. The UV light shows any beans that are affected by a number of defects, higher moisture content, mould, bacteria, and even chip marks from the de-hulling machine. Once the coffee has gone through the UV sorting, it is sorted again under normal light, and from here the coffee is weighed out from a silo into bags for export.