Weighing and Hulling (Removing the Parchment)

When the beans are at 11-12% moisture, they are removed from the parijuelas and bagged. Each bag has the parijuela number that it came from. The bags are then weighed and the results logged.

Weighing and logging the dry beans

Coffee beans have a hard shell covering the bean. Here is the coffee bean anatomy introduced in the Processing the Coffee Cherries article. This illustration from Wikipedia shows the cherry anatomy.

Coffee Bean Structure

Structure of coffee berry and beans:

  1. centre cut
  2. bean (endosperm)
  3. silver skin (testa, epidermis)
  4. parchment (hull, endocarp)
  5. pectin layer
  6. pulp (mesocarp)
  7. outer skin (pericarp, exocarp)

The last step is hulling, or removing the parchment. Processing removed parts 7, 6 and 5. Hulling is the step that involves removing part 4, the parchment. Parts 3, 2 and 1 form the final green coffee bean. Some companies remove part 3, the silver skin, with a machine called a polisher. Most green coffee sold in North America has the silver skin still on.

In these three photos, we see the parchment being removed.

Dry coffee bean with the Parchment still on

A piece of the parchment shell removed

Green bean with the parchment removed

Parchment is removed with a hulling machine. Hullers work by rubbing the beans to crush the parchment, then blowing the light parchment pieces off. Hullers may also sort the beans by size.

Eureka Separator and Grader (American)

In this photo from All About Coffee (1922), by William H. Ukers, we see an old Eureka Separator and Grader.

Hulling Parchment Coffee.

This video shows a modern machine hulling coffee from Matias’ plantation. The output is sorted into two sizes: normal and one for small rejects. These rejects are usually broken beans or peaberries (a coffee pit that did not grow into two beans forming a single bean.)

The next stop for these green beans is the roaster and then a cup of tasty coffee.

3 thoughts on “Weighing and Hulling (Removing the Parchment)”

  1. Fascinating – thanks for the video too. Love the diagram/cross section of the bean.

    Now you’ve made me long for a cuppa that tasty coffee! I’m going to go make some right now.

  2. Hello,

    Do you know where I might be able to find information on a pulp removing machine and a parchment removal machine that can de be delivered or purchased in Guatemala, Central America. I’m having a hard time finding these machines in my country. If you can help, it would help us a lot.

    Sincerely,
    Maria

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