The harvest

 The quality of coffee depends on numerous factors. To begin with, the taste of the beverage depends on the species that is used (Robusta or Arabica) and on the variety that is sown (See History of Coffeefor more information). Besides the genetic factors, the quality of coffee also depends upon the coffee tree and its environment. Such factors, as well as the coffee plantation's agronomic management may affect the coffee tree and the taste of the coffee beans. Furthermore, the adequate harvesting practices all influence the quality of the final coffee product.

In this section we highlight the importance that the harvest and post-harvest have on the quality of coffee. The harvest and post-harvest processes of coffee production are considered as some of the most arduous and sensitive tasks within the coffee production chain. These activities are performed realized by millions of coffee producers in dozens of countries around the world.

 

The Harvest of Coffee

The harvest seasons are related to the seasonality in which the coffee trees blossom in the Tropic. In the case of Arabica coffee, the harvest occurs between 210 and 224 days after the trees have bloomed. The blossoms are induced when the trees have faced the absence of rain for a few weeks. This is known by professionals as hydric stress followed by sustained rainfall. In this way, tropical or subtropical countries that have dry and wet periods(dry and rainy seasons) during the year, tend to have concentrated bloom seasons and, consequently, their harvest is concentrated in relatively short periods of approximately three months every year. The concentration of the harvest season favors harvesting practices by permitting the use of semi-sophisticated equipment to perform these tasks. This, nonetheless, implies the harvest of cherries at their optimal state of maturity as well as those that have not yet ripened enough or that are past their optimal point of maturity. The post-harvest practices are fundamental for separating and avoiding that the coffee cherries at diverse states of maturity spoil the coffee with unwanted attributes.

Colombia is a particular case in the coffee producing world given that its rain regime varies according to its specific regions, which generates different blooming seasons throughout the year depending upon the specific location within the country. In some areas of the country the alternation of dry and wet weather is so prevalent that flowers blossom and produce mature cherries 50 out of the 52 weeks of the year. The irregularity of the harvest season, as well as the altitude of the Andes Mountains where coffee is grown in Colombia, summed up to the gradient slopes where plantations are located, complicate the mechanization of the harvest and favor manual selection of mature cherries.

The Colombian coffee growers are conscious that without the practice of selective harvesting their incomes would be at risk in the mid and long term. In any random branch of an Arabica coffee tree growers can find bulbs that are about to convert into flowers, fully formed flowers, as well as cherries at different stages of maturation. The Colombian coffee producer knows that without a selective harvest they would potentially sacrifice the flowers that constitute their future income or reduce their current incomes by incorporating unripe cherries that would subsequently hinder the quality control tests that their system demands.

The selective coffee harvest in Colombia is one of its principle advantages in the production of superior quality, as it significantly reduces the chances of harvesting cherries at different stages of maturation. The coffee beverage prepared by beans derived from cherries at different stages of development present the following defects:

  • Woody and sour aromas and flavors due to the presence of dry black fruits.
  • Fermentation due to harvesting overly ripe cherries.
  • Astringency because of the presence of unripe cherries.
  • Sour and strange flavors caused by the harvest of cherries perforated by insects.

The presence of 2.5% or more of unripe coffee in a coffee batch will significantly affect the quality of the coffee. In addition, unripe cherries do not depulp completely, thus unripe and black beans can be obtained after being dried and hulled, which will further affect the physical and organoleptic quality of the coffee.

The harvest of mature cherries is not the only process that determines the quality of coffee. In order to obtain a coffee of superior quality the post-harvest process is essential.

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