The natural fermented process starts way before the process itself, it demands cherries at their peak of maturation. Alongside the traditional evaluation of ripeness by the cherries’ color or even by chewing them, the level of soluble sugar content is measured (target: 22-24 ºBrix).
When cherries are delivered to the wet mill to be processed, they are cleaned to remove any juice excretion or dust, but they are not pulped. Then, they’re carefully placed inside the tank containing a natural yeast starter culture called ‘Mosto’.
Once the tank is filled, it will be sealed in order to avoid oxygen contact from the environment and sudden temperature changes. The fermentation process duration can vary depending on the desired flavor profile and pH target. We classify the fermentation periods by long, medium, or short, according to the time spent inside the tanks.
The standard duration times range from 24 to 48h (short); 72 to 96h (medium) and above 96h (long). According to studies related to fermentation and coffee quality, coffee beans’ flavor is directly affected by the acidity in the environment, so producers must consider the pH measurement as an alarm clock to stop the process.
Now it’s time to put the cherries to rest and dry on the raised beds under the UV protection in the greenhouse. The cherries will be revolved and sorted on a daily basis for a period of 30 to 40 days. The perfect drying condition will assure a homogeneous drying and stable water activity. Once the moisture reaches a level of 11.5 to 12% and water activity (aw) from 0.4 to 0.6, the cherries are finally and properly dried.
After tons of work, there’s still a lot to be done. The milling and grading processes are done in dedicated machinery to nano and micro-lots in our warehouse. There’s high risk and complexity in such processes as they are the last steps before the coffee is finally shipped. Any deviation or operational problems will ruin all the hard work done by the farmer and his staff.
There’s a wide variation of fermentation processes and flavors. The process mentioned above is just a starting point.
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