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Bunn Coffee Basics
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THE ELEMENTS OF BREWING PERFECTION
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Water |
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Fresh, good-tasting water is
essential since it makes up more
than 98 percent of a cup of
coffee. Mineral content can
affect taste. For best results,
water should not exceed these
parts per million (ppm) of
dissolved minerals:
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Ideal – 50-100 ppm (50-100
mg/L) or 3 to 6 grains of
hardness
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Acceptable – Below 300 ppm
(300 mg/L) or 18 grains of
hardness
Brewing perfect coffee starts
with clean equipment. Make sure
your brewer is free from any
contamination or odors that
might affect the coffee.
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Temperature |
The temperature of the water
during brewing affects flavor
and extraction.
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Ideal Water Temperature–
195º - 205ºF (92º - 96ºC)
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Time |
| The brewing time or the time water
is in contact with coffee grind
determines the amount of coffee
material extracted, the major
component affecting flavor. |
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Turbulence |
| Turbulence is created as the water
passes through and over the coffee.
It should cause the particles to
separate and create a uniform flow
of water around them for proper
extraction. |
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Filtration |
Paper filters produce the
clearest cup of coffee. BUNN
filters are:
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Porous enough to allow free
flow of the extracted coffee
solubles.
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Made from oxygen processed
paper for best coffee
flavor.
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Strong enough to prevent
collapsing.
Combining these elements for
optimum flavor, productivity and
profit is a science, a science
that BUNN has been exploring for
over 50 years.
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Cleanliness |
Make sure these are clean and free
from lime and hard water deposits.
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Serving area
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Sprayhead / Funnel
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Servers
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Water Reservoir / Pitcher
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HOLDING AND SERVING KNOW HOW
When you brew perfect coffee, it should be enjoyed
while flavor and aroma are at their peak. BUNN offers a range of holding and
serving equipment designed to keep your coffee ate its best. |
Ideal holding temperature:
175 F to 185 F (80 C to 85C)
Most
all the volatile aromatics in coffee have boiling points well below that of
water and continue to evaporate from the surface until pressure in the
serving container reaches equilibrium. A closed container can slow the
process of evaporation. |
Ideal serving temperature:
155 F to 175 F (70 C to 80 C)
Many
of the volatile aromatics in coffee have boiling points above 150 F (65 C).
They simply are not perceived when coffee is served at lower temperatures.
Ideal holding time: 20 minutes in an open top decanter
/ 30 minutes in a closed container. |
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THE SCIENCE OF THE BREWING PROCESS
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The Brewing Process |
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Understanding the brewing process is essential to controlling the qualities that create the ideal coffee drinking experience.
Wetting
The grounds
begin to
absorb the
hot water
from the
sprayhead
and release
gasses from
the coffee.
For
consistent
extraction
from all
parts of the
coffee
grounds, you
must evenly
wet the
entire bed
of coffee in
the first
10% of the
brew cycle
time.
Extraction
The
water-soluble
materials
dissolve and
move out of
the coffee
grounds and
into the
water. The
best flavors
are
extracted at
the
beginning of
the process
as seen in
the Brew
Cycle Time
table.
Hydrolysis
Through this
chemical
reaction,
the
materials
created
during
extraction
break down
further into
water
soluble
proteins and
sugars.
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MATCH THE GRIND
TO BREW TIME |
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The brewing or water contact time is primarily determined by
the grind size and bed depth. A longer brew time is required
for the water to penetrate the larger
grind particles.
The recommended brewing contact times
for each grind size are shown here.
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Brewer Cycle Timing
Your equipment's brew cycle
delivery time assists in
determining the recommended
coffee grind to produce a
perfect cup. Experiment with a
coarser or finer grind to attain
the flavor profile you prefer
for your coffee. |
Bed Depth
The ideal depth of the coffee bed in the brew basket
is 1-2 inches (2.5-5.0 cm). If your
coffee bed is less than 1 inch, the
water may move through it too quickly
and under-extract. Water moving too
slowly through a bed depth of more than
2 inches (5.0 cm) may cause over
extraction and a bitter taste. |
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THE TECHNIQUE OF BREWING CONTROL
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COFFEE BREWING
CONTROL CHART |
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This chart shows
the relationship between brewing ration,
strength and extraction. The amount of
coffee being extracted and the amount of
coffee solubles in the finished cup
determines coffee flavor. |
Brewing Ratio
The
relationship between the amount of
ground coffee used per half-gallon of
water (as shown by the diagonal red
lines) and extraction.
Strength-Solubles
Concentration
The goal for percentage
of coffee flavoring material to the
amount of water in the finished cup is
1.15% to 1.35%, measured by your Brew
Strength Meter or Hydrometer.
Extraction-Solubles Yield
The
ideal percentage of coffee material
removed is 18% to 22% of the solubles.
Optimum Balance
Balancing strength
and extraction creates the ideal cup of
coffee. This standard is designated the
"Golden Cup" by the Specialty Coffee
Association of America.
USING THE CHART
If you use 4
oz. of coffee and the strength of the
brew measures 1.40%, follow the line
labeled 4.00 oz. down the diagonal line
to the 1.40% grid line. This coffee
would be STRONG. To move your brew into
the box labeled IDEAL, you need to
decrease the extraction by decreasing
the brewing time and/or increasing the
grind size.
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KNOW YOUR TERMS
Before you learn about brewing the perfect cup of coffee, it
helps to know what goes into any cup of coffee. The process of running hot water
through coffee removes various materials from the grind. Those materials are:
Soluble Materials: Compounds that dissolve in water.
Non-soluble Materials: Compounds that do not
dissolve in water.
Volatiles: Soluble materials that evaporate easily.
Non-volatiles: Soluble materials that do not
evaporate, but stay in solution.
When people enjoy a cup of coffee, they are experiencing a combination of the
compounds described above. The terms used to describe the coffee drinking
experience are:
Aroma: The soluble volatile materials (gases) that
evaporate, creating the coffee's aroma.
Taste: The soluble, non-volatile materials
(liquids) that are responsible for flavor.
Body: The non-soluble, non-volatile materials
(solids) that determine the way coffee feels in your mouth. |
