We started this feature with The Coffee Tree – Part 1 of “All About Coffee” and now here is part two of All About Coffee covering the coffee cherry as it get harvested, milled, dried and ready for shipping to the US.
Coffee harvesting: Coffee is usually harvested once per year (possibly twice depending on the region source) during the dry season when its cherries ripen to a bright red, glossy, and firm state.
There are two methods of coffee picking: mechanical harvesting by machine and selective picking by hand. The best method is selectively by hand as it decreases the chances of a cherry being picked prematurely. Unripe green cherries result in displeasing bitter flavors with a sharp odor whereas ripe cherries yield more fragrant, smooth, and mellow notes as well as a lower acidity level.
Although this process is preferred, it is labor-intensive since pickers rotate among trees every 8 to 10 days during harvesting season.
Coffee Milling: After harvesting, the coffee cherries must then be set to dry. The oldest and “natural” method of this process is the Dry Mill where the coffee cherries are cleaned and sorted before its exposure to the sun. Depending on weather conditions, those cherries can be laid out on patios for up to four weeks to dry while being raked regularly to prevent mildew and to ensure even drying.
Once ready, the outer coffee layers (pulp and parchment) are removed from the coffee seeds, or beans. After processing, the beans are further inspected and cleaned, and polished to remove any layers left on the beans. This limits the chance of any byproduct (“chaff”) from roasting the coffee beans.
A newer method was introduced, the Wet Mill or “washed coffee”, by using specific mechanical equipment and a substantial amount of water. Within hours after harvesting, the coffee cherries undergo Pulping – removal of the fruit covering; Fermentation – in its own mucilaginous layer with the help of fungi, bacteria, and yeast; Washing – to present a clean, rough, and whitish appearance without any residue, and then Drying – within a humidity level between 10-12%. The Wet Mill process has become the preferred method over the Dry Mill simply because it yields the better quality of the coffee beans.
Coffee Selection and Storage: Once the drying phase is complete, the coffee beans turn into a blue/green color where its almond shape is revealed. The “green coffee” is then sorted by size and density, color and looks, and into grades (i.e. the top three grades in Colombia are Supremo, Excelso, and Milds).
Next, the coffee is packed accordingly into burlap bags weighing up to 70 kilograms per bag. For optimal quality, the packed green coffee must be stored in a dry, clean, well-ventilated space. In fact, aging the green coffee beans for up to a year before roasting has yielded the best flavors and aromas.