THE ESSENCE OF COFFEE
SCAA
Trainer’s Guide to Specialty Coffee
Myth, History, Cultivation through
Export
COFFEE BASICS:
Production through Export
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The Cherry to Bean Ratio
Processing
Wet Process
Fermentation
Drying
Dry Process
Wet vs. Dry
Milling or Hulling
Polishing
Final Sorting
Grading
European Prep
Storage and Shipping
Aged Coffee
PRODUCTION THROUGH
EXPORT
Depending on the system of hand picking
used as well as the layout of the farm, a
picker can pick approximately 100 to 200
pounds of coffee cherries each day.
Since only about 20% of this weight consists
of actual bean weight, the average net yield
per picker per day is 20 to 40 pounds of
green beans.
This is remarkable as is the fact that each
coffee tree annually yields the equivalent of 1
to 1 1/2 pounds of roasted coffee!
freshly picked red coffee cherries
Processing
The next phase in coffee’s journey is
the processing.
Processing is the system of separating
the bean from its outer skins.
The two processes used are the Wet
(or Washed) Process and the Dry (or
Natural) Process.
The Wet Process primarily is used for
arabicas while the Dry Process is most often
used for robustas.
The processing method used plays a huge
role in helping to determine the coffee bean’s
brewed flavor.
Coffees that undergo Wet Processing that
include fermentation typically yield greater
acidity.
Wet Processing
Wet Process
In the Wet Process, coffee cherries first
are sent through a pulping machine.
Cherries must go to the pulping
machine between 12 to 24 hours after
harvest.
To wait too long is to risk significant
deterioration in the cup quality of the
coffee.
The pulping
machine uses
either blades or
a fixed surface
working with a
moving surface
to smash the
coffee cherry in
order to remove
the cherry’s
outer skin and
most of the pulp.
pulping machine
defect and density separation
Fermentation
The coffee beans are soaked for 12 to 36
hours in fermentation tanks in order to
remove the sticky coating around the bean
called the mucilage.
The fermentation process requires delicate
balance.
While fermentation produces enzymes,
which allow the mucilage to loosen from the
bean, it also can occur for too long and cause
rot.
fermentation tank
It takes only 1 rotten bean to ruin a
whole batch of beans!
After fermentation, the beans are
thoroughly cleaned in washing channels
to remove any remaining fruit residue.
As the beans move through the washing
channels, “floaters” are sorted out due
to their low density and poor quality.
washing channel
Drying
Still encased in their parchment, the
coffee beans are sun dried to a degree
of moisture at which they will be
stabilized for shipment.
For arabica beans, this is 9-13%.
This drying process begins by
spreading the parchment-encased
coffee beans on concrete patios or on
drying trays or tables at a depth of
about 2 inches.
beans in parchment
Over the course of 3-5 days, the beans are
raked constantly in order to ensure even
drying.
Throughout the course of the day, beans are
raked in the direction of the sun in order to
most effectively harness the sun’s hottest
rays.
When insufficient labor and/or weather
conditions prohibit it, sun drying sometimes is
supplemented with machine dryers.
raking on the drying patio
These dried beans, now called
parchment coffee, will remain in this
form until just prior to shipping for
export.
If the coffee is under dried, it can spoil.
If the coffee beans are over dried, some
of the quality may be lost.
Once again, this is a story of balance.
coffee dryer
Dry Process
The Dry Process is the most traditional and
least expensive of the 2 methods.
The Wet Process relies on an abundant
water supply.
Countries lacking a wealth of water, such as
Brazil and Ethiopia, use the Dry Process.
With this method, ripe coffee cherries are
allowed to remain on the tree for an initial
drying.
preparing coffees in cherry skin for drying
After the cherries are taken from the
trees, they are spread out on concrete,
tiled, or matted surfaces to a depth of
about 2 inches.
The cherries are left in the sun to dry.
In order to keep them from fermenting
or spoiling, the cherries are raked and
turned frequently for approximately 14
to 21 days.
Dry Process roof patio
During the drying time, the cherries may
be covered to protect them from rain or
cold.
At the end of the Dry Process, the
coffee cherry skin continues to encase
the beans now in a hard, dark shell.
As with the Wet Process, it is important
not to over or under dry the coffee.
Once the beans have been dried to
about 12% moisture content, they are
stored in silos in order to continue the
process for a bit longer.
The drying component of both
processing methods necessarily
reduces the moisture content in the
bean from about 60% to 9 to 13%.
Wet Vs. Dry
The characteristics of the beans processed
by these 2 methods vary.
Wet processed beans:
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Are blue/green to gray/green in color
Have a clean flavor
Lack undesirable elements
Have greater acidity
And tend to command a higher price due to the
extra expense for labor and equipment
Dry processed
beans:
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Tend to be
greenish to
brownish in
color
Have heavier
body
And can
develop offtastes
Wet vs. Dry
Milling or Hulling
The milling, or hulling, process occurs
just before the green beans are
exported.
This process is also referred to as
“curing” the beans.
Using either friction or impact hullers,
the parchment and/or silver skin is
removed from the bean.
huller
Friction hullers use rotors or knives to
peel or grind the skins off of the beans.
Impact hullers rely on wheels, pins,
and the like to shatter the casing
around the coffee bean.
Both methods can be used for either
Wet or Dry processed coffees.
Polishing
Polishing is sometimes used to remove
any remaining silver skin on the bean.
The methodology of polishing closely
follows that of friction hulling.
While polishing can make the bean look
more attractive, the heat from this
process can destroy the acidity, or
brightness, in the coffee.
polisher
Final Sorting
Coffee beans undergo a final sorting at
origin where they are scrutinized by
size, shape, density (the hardness of
the bean), and by color (which ranges
from bluish to brownish).
Sorting is used to remove the defects
from the coffee, which is being prepared
for export.
bean sorting
Sorting also is used to batch coffees
together, which possess similar physical
characteristics. Such batching allows for
consistent roasting quality.
While coffee beans at this point undergo
a rigorous series of final sortings,
throughout processing unacceptable
beans are removed upon detection.
Peaberries
too are sorted
out to be sold
separately
and often at a
premium
price.
Coffee beans
are sorted by
utilizing 3
methods.
screen sorting
The first method is gravity and screen
sorting which separates beans by common
density and size.
Employing mechanized or hand held screens,
beans of the designated size and weight fall
through precisely sized openings.
A simple mechanized system uses blasts of
air aimed at the beans.
The lightest,
lowest density
beans are
lifted out of
the pack by a
blast of air
and are
subsequently
removed as
undesirable.
Electronic Sorter
A more sophisticated system is Electronic
Sorting, which scans the beans as they pass
in front of a photoelectric cell in order to
measure the amount of light reflected off of
each bean.
Those beans that do not meet the proper
criteria are sorted out.
A more advanced version of this method uses
a bichromatic light to analyze the proper color
of the bean.
Again, those not meeting the proper
criteria are picked out.
Ultra violet lights also are used in order
to detect fermentation, which is not
visible to the naked eye.
hand inspection
on conveyor belt
The final method of sorting is to pick out
the defects by hand as the beans pass
over a conveyor belt.
Defects include black beans, broken
beans, stones, or debris found in a
coffee sample.
Once sorted, the beans are ready for
grading.
Grading
Criteria for grading may include altitude of
growth, density, and bean size of the bean.
Each country of origin determines the criteria
that it will use to sort, grade, and label their
coffee beans.
For example, Kenya identifies its top grade,
AA, by the size of the bean.
Another country, which grades its coffees by
size, is Colombia. Here Supremo beans are
larger than are Excelso beans.
grading
Costa Rica uses altitude as one grading and
naming criterion. It categorizes Costa Rican
Strictly Hard Bean (which grows at 3600 to
5200 feet above sea level) as superior to the
Costa Rican Hard Bean, which is grown at a
lower altitude.
Other coffees carry the names of the
ports through which they are commonly
exported. An example of this is Yemen
Mocha.
And still others are given the name of
the region in which they are grown—as
is the case with Ethiopian Harrar.
European Prep
As we have seen, the care taken in the
processing of the coffee beans, as in every
other step of the cycle is critical in
determining the quality that we find in our
own cup.
European Prep refers to the extra attention
and care that is taken with some arabica
beans to ensure that they are free of any and
all potential defects.
These coffees are given extra care in
the washing process, in the scrutiny of
defects, and in the hand sorting to
ensure uniformity in bean size.
Additionally, these beans are polished.
This extra attention results in a price up
to 10% higher than other high quality
arabicas.
Storage and Shipping
Before coffee makes its final journey to
export, it must be bagged in jute, hemp, or
sisal bags (burlap) and in weights ranging
from 100 pounds (or 45.36 kilos) to 152
pounds (or 69 kilos).
The material for these bags is inexpensive
and readily available in the countries of origin.
It also provides valuable protection to
the beans.
Since these bags “breathe”, they do not
trap any moisture in the beans, which
can cause the beans to mold.
bagging
Typically, the country of origin, grade
of bean, and the method of
processing, are printed on the bag.
bags in
warehouse
Ventilated warehouses often are provided for
coffee storage in many countries of origin.
These warehouses are designed to protect
the green coffee beans from absorbing
moisture and odors.
Coffee labeled and stored as a “new
crop” is one that has been harvested
during the current crop year.
A “past crop” label refers to a crop that
has been harvested from a prior year.
Typically these older crops are sold at a
reduced price.
Aged Coffee
Certain coffees are stored in their
parchment for several years.
These coffees are being “aged” in order
to develop a smoky characteristic
created by the chemical changes within
the beans.
Aged Sumatra is one such coffee.
Due to increased expense stemming
from long-term storage, these aged
coffees command premium prices.
Shipping
When coffees are bagged and ready for
export, they are loaded in containers
which each hold up to 250 bags of
coffee.
They are then shipped or in some cases
flown to destinations around the world.
loading the ship