Post-harvest

The post-harvest processes, which is commonly referred to as the beneficio in many countries, vary according to the country where coffee is produced, the type of cultivation and the species of coffee used. It serves in transforming the coffee cherry into a dry product ready to be roasted.

The post-harvest process, begins as soon as the coffee cherries have been harvested. In order to understand the importance of these processes, it is convenient to take into account the composition of a coffee cherry. The mature coffee bean is either red or yellow in color. Each bean has an exterior skin (exocarp) that wraps around a sweet pulp like substance (mesocarp). Under the pulp are beans covered by a delicate and translucent membrane (silver skin) and these layers sheath the two internal coffee seeds (endosperm). The green coffee seeds are roasted in order to elaborate the beverage that consumers recognize as "coffee".

Thus, the post-harvest activities refer to the processes that are used in order to separate the mesocarp from the endocarp. The time that these processes last and the effects that the different coffee pulp and mucilage compounds generate on the bean have a clear influence in the quality of the final beverage.

One of the most common processes is called the dry beneficio. During this post-harvest process the cherries are usually exposed to the sun for several days until they have reached a certain range of humidity levels. One of the effects that this method has is the impregnation of the coffee seed with certain sugars as well as other compounds present in the mucilage. Due to this dry process, the coffee gets particular flavors and characteristics.

The wet beneficio of coffee includes depulping, fermentation, washing and drying the coffee bean. In the first step the coffee bean is depulped immediately after being harvested; if this takes more than 6 hours, the beverage can obtain a fermentation defect. This defect can also present itself through cherries that have not been depulped entirely or at all, and that have come into direct contact with parchment coffee, or when a greater percentage of over ripe beans have been harvested.

Subsequently the mucilage is removed by means of hydraulic fermentation or mechanically. The fermentation can last between 12 to 18 hours depending upon the following variables:

  • The temperature of the location: more time is needed in colder regions.
  • The height of the specific layer of coffee within the fermentation tank: the greater the height within the fermentation tank of the layer of coffee the less time that is need to ferment.
  • The use of water: dry fermentation is recommended as it accelerates the fermentation process; the run-off water from washing the coffee beans should be allowed to drain from the fermentation tanks.
  • The grade of maturity of the coffee beans.
  • The amount of mucilage per coffee bean.

Because the time needed to ferment the coffee beans is a definitive factor in the quality of the coffee, it is necessary to obtain periodic samples of the mass of coffee in the fermentation tanks in order to determine the optimal point to initiate the final coffee beans washing process. If the coffee is overly fermented it will stain, loose weight, become vinegary and its quality will be irredeemably affected.

A Mechanical wet beneficio is also an alternative method. The technology of the ecological beneficio developed by Cenicafé and commonly known as Becolsub or Ecotec, has permitted the optimization of the coffee bean's wet beneficio process, saving substantially the use of water.

Once the fermentation process has been completed, the beans are washed in order to eliminate the mucilage from the bean. In this way the pulp is quickly separated from the mucilage and washed thus eliminating the risk of the bean acquiring any defective flavors.

The wet beneficio process constitutes both an arduous and hypersensitive job that is intimately linked with the Colombian Coffee tradition and constitutes one of the principal elements in guaranteeing the quality of coffee. In this process impurities are eliminated and the selection and classification of coffee is enabled.

Once the coffee has gone through the wet beneficio process it is dried naturally through exposure to sunlight or in mechanical dryers. Once the coffee seeds have been dried they are commonly referred to as parchment coffee, since they are still wrapped up in a protective parchment like yellow skin.

The coffee grains are submitted to another process referred to as coffee hulling after the wet beneficio and drying processes have been completed. This process serves to remove the parchment from the beans in order to obtain green coffee to be roasted. Once the beans have been milled or hulled the green coffee seeds are cautiously selected and classified in terms of size, weight, color and physical appearance (defects). Green coffee is the prime material for the industrial processes that obtain roasted coffee, soluble coffee and coffee extracts. It is characterized by its green color, its fresh coffee scent, and an average humidity that ranges between 10% and 12%.

We have seen that the elaboration of quality coffee is a difficult and extended process. In the section titled The Quality of Coffee, we will evaluate the way all of these processes translate into the well known and appreciated qualities of coffee.It is clear, however, that the quality associated with a Colombian mild washed Arabica coffee is associated not only with washing an Arabica bean. To have a mild coffee the location and handling of the plantation, the wet processing method used, the production at high altitudes with particular Arabica varieties at certain temperature ranges, and in particular soils are all important contributors to the quality and taste. 

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