Beneficio Rio Tarrazu

Los Santos | Costa Rica

About

Our coffee mill, Beneficio del Rio Tarrazu, is located on land adjacent to Hacienda La Minita, just across the Tarrazu River. We believe our mill to be the most technologically advanced and ecologically sound coffee processing facility in the world.

WET PROCESSING

The coffee arrives at the mills in large trucks. These trucks pick up the coffee from the receiving stations (recibidores) on the farms and transport it through the mountains to the mills. It is critical that processing of the coffee begins within 24 hours of the coffee being picked from the trees. If the processing is delayed, the fruit will begin to spoil ruining the coffee seeds contained within the cherry.

As the coffee is unloaded from the trucks, it is measured into a large rectangular container called a medida. The bottom of the medida his hinged to allow the coffee to be dropped into the receiving tank after being measured. The receiving tank is filled with water, and it is here that the first quality separation takes place. Any overripe (bellota), seedless (grano vano), or unripe green (verde) cherries float to the top of the tank due to their lower densities. These are channeled off to be processed separately.

The dense ripe fruit sinks to the bottom of the tank, and is moved via a siphon through a destoner (despiedrador). The destoner will remove any stones or heavier density items that may have inadvertently gotten mixed in with the cherries.

A depulper (chancador) then removes the outer skin from the seeds and the miel. It does this by cutting the skin and squeezing the fruit between an inner drum and an outer surface. The distance between the drum and the surface needs to be carefully adjusted to ensure the seeds are not crushed by the depulper. The skins of the coffee are collected and typically trucked back to the coffee farms to be used as a mulch.

The coffee then moves on to a criba. A criba is a cylinder made of bars separated by a precisely measured distance. A screw conveyer moves the cherries through the criba. The purpose of this step is to remove any cherries which did not have the skins removed in the depulper (this may be due to small size or hard unripe fruit) from the properly depulped seeds. The depulped seeds (first quality) fall through the bars of the criba and move on to the fermentation tanks, while the undepulped fruit moves on for further processing (second and third qualities).

The coffee spends between 20 and 24 hours in the fermentation tanks (pilas de fermentacion). The fermentation process will break down the sugars in the miel, making it easier to remove the mucilage from the seeds. However, if the coffee remains in the fermentation tanks for too long, the coffee seeds will pick up the taste of rotted fruit. The mill manager makes the all-important decision on when to remove the seeds from the fermentation tank.

From the fermentation tanks, the coffee seeds move to the washing channel (caño de lavado). The washing channel serves three purposes. First, the cool temperatures of the water halt the fermentation process that is occurring within the coffee mass. Second, the mucilage, which is now loosened from with the coffee seeds, is washed away, along with any other loose material that has gotten into the coffee (ie. dirt, loose skins). Third, a skilled mill worker will make quality separations of the coffee based on the specific gravity of the beans. The lightest lower quality beans will flow down the channel first, while the most dense flavorful beans will move more slowly. The qualities are separated using a series of slide gates and channels.

TRANSITIONAL STEPS

From the washing channel, the coffee is placed into the mechanical driers (secadores) for the final drying stage. These driers are set at 60 degrees Celsius (140 F) using indirect heat and slowly rotate to evenly finish the drying. Again, the mill manager makes the critical decision on when to remove the coffee from the dryer based on its feel, and the ability to remove the parchments skin from the seed. After the coffee is dropped out of the drier, it rests for about 10 hours before being moved. A typical drier load consists of approximately 60 quintales or 6,000 pounds of coffee.

The furnaces used to supply the heat for these driers have recently been replaced with new state of the art furnaces. These furnaces are fueled using the parchment shell removed from the beans during the final preparation for the coffee. This as almost completely eliminated our use of wood as an energy source.

At this point, the coffee seed is covered by a hard shell (called the parchment), as well as a thin layer of silverskin. The coffee is moved into large silos, and remains resting for at least 20 days. This period of time is called reposo.

DRY MILLING

The parchment coffee is run through a huller. This will remove the parchment from the seed as well as the silverskin. The removed parchment is used as a fuel for the coffee driers.

A catadora is then used to separate the coffee by density. This is done by using a flow of air to draw the coffee up a chute with various gates.

The green coffee then moves through a screener to separate the coffee by bean size. One of the best screening machines for this step in the process is a modified grain separator which was made in Scotland. These machines are extremely accurate (operating using a series of precisely measured holes), and more importantly, very gentle on the coffee. We are in the process of collecting as many of these machines as possible for use in our new mill.

Further sorting occurs with the winnower. The winnower is a slanted table that vibrates, shaking the coffee and separating lesser density coffee from higher densities.

The last step for La Minita coffee is the hand cleaning tables. Here women pore over the coffee looking for a discolored or damaged beans that were not separated by the machines. A top sorter can clean no more than 50 pounds of beans in one day.

MILLING SUMMARY

The milling of the coffee is critical in determining the final quality of the coffee. Not only are there chemical changes occurring within the beans that will determine their final cup quality, but also a series of separations that remove the lower quality beans. Of 100 pounds of green equivalent cherries that enter the milling process, only about 23 pounds make it to become La Minita.