Processing The Kona Coffee Bean

Once the cherry is harvested, it is time to process the Kona coffee bean.

  1. What happens to the cherry after they are picked?
  2. Do the farmers pulp the cherries?
  3. What are Kona Nightingales?
  4. What happens to the beans after they are pulped?
  5. How long are the Kona coffee beans left in the fermentation tank?
  6. What happens to the Kona coffee beans after they are taken out of the fermentation tank?
  7. How long does it take to dry the Kona coffee beans?
  8. What happens after the Kona coffee beans are dried?
  9. How are the coffee beans processed after they are dried?
  10. What is milling?
  11. What happens after the parchment is removed?
  12. How are Kona coffee beans classified?
  13. What happens once the crop is processed?
  14. Do some Kona coffee farmers process their own coffee beans?
  15. How many Kona coffee farmers sell their gourmet Kona coffee under a private label?


After the coffee cherry are picked they are first run through a pulper that removes the outer flesh—the red skin and sugary mucilaginous pulp—and separates the beans from the pulp.  The pulper uses rough rollers to break up and loosen the outer skin of the cherry and remove the fleshy mucilage surrounding the coffee beans.  Pulping is usually done within the first twenty-four hours after picking, and then the beans are washed in clean water.  Any “floater” seeds that are empty or perhaps not ripe enough are discarded.


Most Kona coffee farmers sell their cherry crop fresh off the tree to Kona processors but some farmers process the cherry themselves and then sell the crop as parchment (pulped, fermented, and dried coffee beans), or as green (milled, unroasted coffee beans).  Some Kona coffee farmers run a complete Kona coffee company and take the process to the very end by roasting their coffee and shipping it directly to the consumers.


Kona Nightingales are the donkeys that were used to carry coffee cherry across Kona’s rocky lava landscape to the coffee mills nearer to the ocean.  At the end of World War II military jeeps began to be used to carry the coffee cherry.  Many of the donkeys were released on Hualālai Volcano and remnants of the herd still remain in the region north of the Kona airport near the Kona Village Resort and Four Seasons Hotel.


After the coffee beans are pulped they are carefully fermented in a fermentation tank.  This wet-method processing is said to create the bright, clear flavor that is characteristic of Kona coffee.


The length of time that the Kona coffee beans are left in the fermentation tank depends on the temperature, and thus the elevation, of the site.  At lower elevations it only takes about twelve hours or less in the fermentation tank, but at higher elevations it may take twenty-four hours in the tank.  It is very important that this is done before the cherry begin to ferment on their own because the strong, unpleasant flavor that may occur can contaminate all the beans of the batch.


After fermentation, the Kona coffee beans are rinsed in clean, fresh water.  At this time the washed beans have a moisture content of about 27%.  The beans are then spread out on a flat surface, or drying rack (floor/deck/platform)—which is known as a hoshidana—to dry in the sun and the warm Kona breezes.  A traditional hoshidana has a rolling roof so the premium coffee beans can be exposed to the sun during the heat of the day and then covered when it begins to rain, which usually occurs during the afternoon and at night.  These gourmet beans are also raked regularly with a wooden rake so they dry evenly.


Natural sun-drying the gourmet Hawai‘i coffee beans takes from one to two weeks.  The drying is completed when the moisture level of the coffee beans is between 9.5 to 13 percent.  Drying may be completed much faster using a rotating hot drum dryer which may take only a few hours, though natural sun drying is considered the preferred method to produce the very best gourmet beans.


Once the gourmet coffee beans are dried they are stored as parchment (also known as pergamino).  As long as the moisture content is below 12% the parchment may be stored for lengthy periods of time.  The gourmet coffee beans are stored in burlap bags within cooled vaults that are about 65 degrees Fahrenheit and have a humidity level of about 65%.


After the premium coffee beans are dried they are eventually milled and roasted.


Milling is the process of removing the stiff, paper-thin, white skin (membrane) called parchment and the thin silverskin beneath it.  Hullers are used to remove the parchment and also polish the gourmet coffee beans.


After the parchment is removed then the gourmet Kona coffee beans are sorted and graded to the State of Hawai‘i Department of Agriculture standards.  The state will inspect and certify as to grade the sorted and milled Kona coffee beans.  The sorting and grading process involves separating the gourmet coffee beans into quality grades primarily by using screens with graduated hole sizing that separate the premium coffee beans by size and shape.  Also used is a vibrating air table that employs gravity to separate and grade the beans by density, and this isolates the defective coffee beans (e.g., nicked or hollow beans) which can harm the final product if not removed.


Kona coffee beans are classified according to the seed/bean type. Bean types are further broken down into different grades of the Kona coffee.


Once the gourmet coffee crop is processed, most of the processed Kona coffee beans are bagged in 100-pound sacks and then sold on the world coffee market as gourmet green (milled, unroasted) coffee beans.  Most of these green Kona coffee beans are used to add flavor to other less expensive types of coffee (e.g., coffee beans from Brazil, Africa, Indonesia, or Central America).  These mixtures may then be sold as “Kona Blend,” which is a controversial subject in the Kona region as many local farmers would rather not have the gourmet Kona name tarnished by inferior coffee products.


Yes, some Kona coffee farmers custom roast their own gourmet coffee beans and then sell them under a private label.  Some farmers run a complete Kona coffee company and maintain quality control of the coffee from seed to cup by doing their own pulping, drying, milling, sorting, roasting, packaging, labeling, and marketing of their gourmet Kona coffee.


There are more than 100 private labels of gourmet Kona coffee currently offered.

Next: Kona Coffee Roasting

Also see:

How To Buy A Coffee Grinder - Best Coffee Grinders

For excellent coffee knowledge see All About Coffee for information about coffee plants and coffee cherry and the world’s finest gourmet coffee beans.

Tips on espresso brewing can be read about beginning with Pulling A Perfect Espresso Shot and Steaming and Frothing Milk.

Also see the best Coffee and Espresso Glossary along with the World’s Best History of Coffee.


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