Dr. Fix\'s Beer Color Article (2 of 2)

[fredriks]

BRIESS COIOR TEST
This is a simple test designed for homebrewers and
microbrewers. Comparisons have shown that will give color
readings with errors more than on percent for beer whose color
is 17 degL or less. Beer whose color exceeds 17 degL will be
essentially black in appearance. It is not particularly
important to quantify color beyond this point.
The standard for this test is Michelob Classic Dark. The reason
is that it is widely available, and its color is known (17 degL).
On very rare occasions one will come across old bottles of this
beer where haze has developed because of mishandling by
distributors. These should not be used in this test. By the same
token, the sample to be tested should clear and free of haze.
The test consists of diluting the standard with water until a
color match with the sample is obtained. Figure 2 gives the
relationship between the amount of water added and the degL of the
sample.

This is an approximate Graph Plot. Points to plot
your own accurate plot will be provided if interest
is shown.

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15 . x . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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10 . . . . .x. . . . . . . . . . . . . . . . . . . . . . . . . L
. . . . . x . . . . . . . . . . . . . . . . . . . . . . . . O
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. . . . . . . .xx . . . . . . . . . . . . . . . . . . . . . V
. . . . . . . . xx. . . . . . . . . . . . . . . . . . . . . I
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5 . . . . . . . . . . . xxx . . . . . . . . . . . . . . . . . N
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0 50 100 150 200 250 300
Va = Dilution Water, ml

MATERIALS NEEDED
1. Distilled water--Colored tap water can increase
the errors in this test from I percent to 10 or 20
percent.

2. Blender--Dissolved CO2 in the beer will affect its
color. Both the standard and the sample should be
degassed. This can be done in a blender. A lot of foam
will be created, but once it recedes and the beer falls
clear it is ready for testing.

3. Light source--It is important for the visual
comparison to take place in a well-lighted environment.
Ideally, this consists of a lamp with a 100watt bulb
against a white background. Be sure to use the reflected
rather than direct light, and place the samples the same
distance from the light source Also, take time in making
the comparison because the difference in one or two degL is
not that great.

4. Vessels--These are the most important components to
this test. After extensive experimentation it became
clear that two sets are needed. For detailed testing, two
glass jars of one-inch diameter and a capacity of at
least 125 milliliters are best. For samples below 10 degL
the volume of these vessels is not large enough. Two
white 12-ounce export (long neck returnable bottles will
be needed. The Miller Brewin Co. has been using these
bottles. So has Corona, but the label, which cannot be
removed, is a distraction.
5. Syringe--This is needed to measure 10 cc = 10 ml of
water.

PROCEDURE
1. Clean everything.
2. De-gas standard and then sample in blender.
3. Measure in 20 ml of standard beer in export bottle No. 1.
4. Measure in 20 ml of sample beer in export bottle No. 2.
5. If colors are different, measure in 10 ml of distilled
water to bottle No. 1 and 10 ml of sample beer to export
bottle No. 2.
6. Continue Step 5 until colors become close. At this
point the comparisons should be made in the one-inch
diameter jars. Transfer 25 to 50 ml into these from the
export bottles and return after comparison. Cut the water
and sample beer increment from 10 ml to 5 ml.
7. When a color match is obtained, record the total
amount of water added. Figure 2 gives the associated degL.

EXAMPLE - BASS PALE ALE
At the start the 20 ml of standard beer (Michelob Classic
Dark) will be discernibly darker than the sample (Bass). After
adding 30 ml of water to the standard, the colors will become
close, and at this point the one-inch jars are needed. A match
is obtained after an additional 10 ml of water is added. Thus a
total of 40 ml of water was needed, and from Figure 2, we see
that Bass has a color of 10 degL. Since only 60 ml of liquid was
used in each bottle, the entire test could have done in the
one-inch diameter jars.

Note that the relationship between degL and dilution water is not
linear. For example, adding 20 ml of water to 20 ml of Michelob
Classic Dark (17 degL) will not cut the color in half. In fact,
instead of 17/2 = 8.5 degL the color will be higher, namely 13 degL
(see Figure 2). This lack of proportionality is why the
relationship between degL and degrees EBC can be in error. It also
explains why beer color and malt color are not proportional.

At the lower color range, on the other hand, proportionality is
approximately valid. Thus, diluting 20 ml of Molson Export Ale
(4 degL) with 20 ml of water will give a color very close to
Budweiser (2degL). More generally for beers whose color is 4 degL or
less, the curve in Figure 2 is given by

degL = 4(140/VA + 20)

where VA is the dilution water in ml.

(The author acknowledges the significant contributions made
through conversations with Roger Briess. In fact, the simple
color test described above is essentially his idea. The author's
contribution was to work out the data represented in Figure 2.)

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Fredrik Ståhl Tel: int + 90 166027
Math. Dept., Umeå University Fax: int + 90 165222
S-90187 Umeå, SWEDEN E-mail: fredriksPÅabelPUNKTmathPUNKTumuPUNKTse
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