Drying

PC 6.01 Drying Patios

When drying coffee on the ground, the layer of beans should be no more than 5 centimetres (2 inches) deep for fresh cherries and 2.5 centimetres (1 inch) deep for wet parchment (Wintgens, 2004). If layers are too thick, the drying process can take too long. The trouble for some producers is that the patio size requirements for drying coffee in a reasonable amount of time can be huge for some farms. And if a farm produces natural-processed coffees, the land area requirements are considerably higher. According to Wintgens (2004), 1 tonne (1.12 US tons) of fresh cherries being put through the natural process require 20 square metres (215 square feet) of drying area. Piled at a 5–6 cm depth (40 kg cherries/m²), they will take approximately 3 weeks to dry. In Brazil, it is recommended that the size of the drying patio be calculated as 5% of the number of coffee trees in production (e.g., 100,000 coffee trees × 0.05 = 5000 m²).One tonne of pulped coffee needs far more room to dry: 80 m² of drying area is needed for coffee at a depth of 3–4 cm (10–12 kg wet parchment/m²). Drying time for wet parchment is approximately 14 days. Regardless of what process millers use, they usually rake cherries and parchment into piles during the midday, when the UV exposure is at its most intense. Depending on the intensity of the light in a particular region, lots will often be protected during the hottest hours of the day by a roof or a plastic film. The reason for this level of care is that the parchment layer is prone to developing fissures (small cracks) if it is exposed to too much sunlight. The undamaged parchment — and the skin, in the case of naturals — provide the ideal protection for coffees, all the way up until lots are ready for dry-milling just prior to export. Protecting the parchment and skin is important in order to lengthen the coffee’s shelf life.