Measurement Method
MM 5102.00
Measuring Ground Coffee
with ColorFlex EZ Coffee
INTRODUCTION
There are several quality parameters for coffee
but the color of ground coffee has long been
important determinant of quality as the degree of
roast directly affects the flavor and appearance
of the brewed coffee beverage.
Measuring Ground Coffee
MM 5102.00
2
A HunterLab ColorFlex® EZ Coffee is used to measure ground coffee through the bottom of a clear plastic
dish. It is a CIE-conforming mini-bench spectrophotometer optimized for measuring the color of all materials
in agreement with visual observation with a special firmware for the color measurement of ground coffee. It
can be operated as a stand-alone coffee color meter or attached to EasyMatch QC software.
The Application
Ground coffee is reasonably uniform across
the surface but as a particulate, must be measured in a container. While ground coffee can be measured
port-down with the ground coffee raked even with the lip of the dish, measuring port-up through the clear
bottom of a plastic dish is less operator-dependent in terms of sample preparation.
Note: If inter-instrument agreement is a concern when measuring ground coffee, all the instruments used for
these measurements MUST be the same model to minimize measurement differences.
Recommended Color Scale
For coffee products there are three specialized
single number indices in popular use:
• SCAA/G - the Agtron number for the Gourmet
•
•
•
Coffee Scale adopted by the Specialty Coffee
Association of America www.scaa.org. This
scale is based on a series of SCAA visual color
standards used to rate the color of ground
coffee.
SCAA/C - the Agtron number for the
Commercial Coffee Scale adopted by the
Specialty Coffee Association of America based
on the SCAA/G scale.
HCCI - the Hunter Coffee Color Index based on
reflectance at 640 nm, a common metric for
many coffee roasters.
As an additional option, CIE L*, a*, b* D65/10 is
also available as a complete color descriptor
for coffee and other products.
Figure 1. Self Contained ColorFlex EZ Coffee
Figure 2. Visual SCAA Roast Coffee Color Standards from “very
light” to “very dark”.
Measuring Ground Coffee
MM 5102.00
Measurement Method
for ColorFlex EZ Coffee (sensor only)
1. Once a day, go to Main Menu/STANDARDIZE to
standardize the instrument in reflectance.
2. Standardize the instrument using the black glass
and calibrated white tile standards that come with
the instrument.
3. Go to Main Menu/Read/Select Setup #1
“Coffee Roast”.
1.
Note: A product setup is a set of operating parameters
that define the operation of the system for a specific
product. The Coffee Roast setup has three pre-defined
views – one for SCAA/Agtron # for the Gourmet Coffee
Score, a second for the Commercial Coffee Score and
a third for the HCCI Hunter Coffee Color Index. Other
views can be configured to report CIE L*, a*, b* D65/10
and other color values if needed.
2.
4. Place the Coffee Tile at the port and read the
color. It should read closely to the Values-Read-AtFactory on the back of the tile.
Note: If the Coffee Tile does not read closely to factory
values, clean the tile with isopropyl alcohol (IPA) and
a tissue. Then re-read the tile.
3.
5. Fill the bottom of the 100 mm diameter plastic
dish to near the top. Tap once on a hard surface
and place at port. Take a reading and report
the measured values.
Note: Ground coffee is typically prepared by grinding
roasted beans to a medium grind per SCAA
recommendations. The coffee should be fresh ground
from beans each time as oxidation can influence the
ground coffee color. Temperature is also a variable but
by the time beans pulled from the roaster have been
ground and taken to the instrument for measurement,
the temperature should be close to ambient.
4.
5.
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Measuring Ground Coffee
MM 5102.00
Measurement Method
for ColorFlex EZ Coffee used with
EasyMatch QC Software
Note: When the ColorFlex EZ Coffee sensor is used with
EasyMatch QC software loaded on a PC, all actions are
taken in EasyMatch.
1. Initianl set-up: go to Help/About to verify that you
have EasyMatch QC version 4.82 or higher.
2. Go to Sensor/Install-Configure to install the
ColorFlex EZ Coffee sensor with the software.
3. Select Sensor/Standardize to standardize
the instrument using the black glass and calibrated
white tile standards that come with the instrument.
1.
4. Place your mouse over the Color Data Table/
Right Click/Configure to configure all parameters
for coffee color measurement.
Under “Indices” find the SCAA/G (SCAA/Agtron
Gourmet Color Scale) and HCCI (Hunter Coffee
Color Index) metrics found under Indices. Just push
them over into “Selected Items” on the left.
If you need full color values, you may also select
CIE L*, a*, b* in “Scales” for D65/10 Illuminant/
Observer. Other typical parameters chosen would
be to deselect “Tolerances” and increase “Font
Size” to 14.
2.
5. This is what a typical color data display might
look like.
Proceed to measure your PQ Coffee Tile and
compare your measured values to the ValuesRead-at-Factory on the back of the tile.
3.
If in close agreement, proceed to measure your
ground coffee sample through the bottom
of the plastic dish.
5.
4.
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Measuring Ground Coffee
MM 5102.00
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More Information about
Measurement Methods at
hunterlab.com
About Hunterlab
HunterLab, the first name in color measurement, provides ruggedly dependable, consistently
accurate, and cost effective color measurement solutions. With over 6 decades of experience
in more than 65 countries, HunterLab applies leading edge technology to measure and
communicate color simply and effectively. The company offers both diffuse/8° and a complete
line of true 45º/0º optical geometry instruments in portable, bench-top and production in-line
configurations. HunterLab, the world’s true measure of color.
© Hunterlab 2016
Hunter Associates Laboratory Inc.,
11491 Sunset Hills Road, Reston, VA 20190-5280 USA
helpdesk@hunterlab.com
www.hunterlab.com