White Labs Inc. held the first-ever large scale testing of craft beer
in February-March and the results could shed light on the industry in
For "Big QC Day," breweries were invited to send in
two samples of beer (using equipment and boxes provided by White Labs).
The idea was to bring in a large volume of beer samples and perform the
tests at one time in order to make the program affordable. The cost was
$99 for two samples. The hope was that breweries would learn about their
beer and become more interested in quality control issues.
If breweries focus on QC testing, the overall quality
of craft beer will rise. Some small breweries have little or no testing;
most mid-sized to large breweries test for contamination on every batch.
The Big QC Day program shows that the tests are useful and important not
just for the largest breweries in the world but also neighborhood
brewpubs and microbreweries.
White Labs had many more participants than
anticipated, forcing the laboratory to bring extra people into the
project and delaying the results by several weeks. During testing in
February and March, the laboratory was inundated with boxes from around
the country and world, including Sweden and Israel. It is believed to be
the first large-scale testing of craft beer in history. Breweries often
get their beers tested when a problem arises, but what makes these tests
different is that the results provide an accurate picture of craft beer
While individual results are confidential, the
overall numbers will be available on the White Labs website, most likely
by the time this story is printed. While these specific numbers will be
discussed in greater detail in this publication later, a few
observations can be made at this time. For one, 80 percent of the
samples were free of contamination, which is both a positive sign as
well as an indication that many breweries could improve their beer just
with quality control programs that could rid their beer of
White Labs is planning future tests, most likely once
a year in February, just like this test. have future tests. Brewers are
invited to give input about the program at the Craft Brewers Conference
in Austin, Texas. Visit www.whitelabs.com for more information about the
Below you will find a more detailed discussion of the
individual tests that were performed.
Testing Note: All of the tests and samples were
tracked using White Labsí in-house YeastMan computer program. Each test
sample was bar-coded, and these labels did not identify the beers or the
brewery, eliminating any potential for bias.
IBUs: The IBU scale provides a measure of the hop
derived bitterness of beer. The higher number, the greater the
bitterness. Porters range between 20 to 40, for instance, while India
Pale Ales are 40 or higher. The American Society of Brewing Chemists
International Method, bitterness units, is used. Iso-alpha acids are
chemically extracted using the organic solvent iso-octane. The
ultraviolet light absorbance is measured in a precision
spectrophotometer, and the results are reported in bitterness units.
Real Extract: This test shows you the sugars that are
left in beer, usually non-fermentable carbohydrates. Real extract
involves accounting for the alcohol, which we were able to do since we
measured alcohol in the samples. Alcohol has less density than water, so
if you measure straight density it does not account for the subtraction
of alcohol. Results are reported in Plato.
Color: A spectrophotometer is used to measure the
absorbance of a sample at a certain wavelength. The sample is separated
from solids, and the absorbance at a wavelength 430 nm is measured. The
number will show how light or dark the beer is. It can vary between 2
Lovibond to 100 Lovibond. A stout obviously would be high because it is
Density: This is the specific gravity of the beer.
Values depend on styles. We use an Anton Parr density meter (not a
hydrometer) for this test, which gives us a higher degree of accuracy.
Alcohol: We are using a gas chromatograph machine for
measuring alcohol. The detector we use is a Flame Ionization Detector
(FID). Results are reported as % vol/vol. The GC method is more accurate
than most other methods.
Total VDK (including diacetyl): VDK (vicinal
diketones) consists of diacetyl and 2,3-Pentanedione. The test includes
heating the sample, which drives diacetyl precurses to diacetyl. The
lower the number the better, in most cases. If you are under 100 ppb you
are doing well. The numbers vary depending on the yeast strain and
fermentation procedure. If the number is high, perhaps in the 200 range,
the brewery may not be performing an adequate diacetyl rest. Or again,
it could be the yeast strain. Examples of strains with higher VDKs are
the British strains and some lagers. Very high VDK levels can be an
indication of contamination. Additional tests can be performed that can
separate diacetyl and 2,3-Pentanedione levels.
Lactic acid bacteria (or anaerobic bacteria): This
test was conducted using Hsuís Lactobacillus medium, or HLP. This medium
is used to look for the presence of Lactobacillus and Pediococcus. These
bacteria are anaerobic, heat sensitive bacteria. They are called "beer
spoilers" because they are most often associated with post wort
production contamination. The industry standard is less than 10 colony
forming units (CFUs) per ml. If it is over 10, the beer may develop
flavor problems. However, any CFUs found from this test should cause
concern and an evaluation of your brewing and packaging process.
Aerobic bacteria: This test was used with
Wallersteins Differential, or WLD, medium. This medium is used to check
for bacteria and some non Saccharommyces-type wild yeast. Most aerobic
bacteria will grow on these plates, and some anaerobic bacteria also
display growth. Bacterial contamination seen on these plates is termed "wort
bacteria" because they are most often associated with wort
contamination, usually causing most of their damage before the onset of
fermentation. As for the numbers, the same applies to aerobic bacteria
as in the paragraph above about lactic acid bacteria, or anaerobic
bacteria. Sometimes aerobic bacteria are already dead by the time this
test is performed, after fermentation and packaging, but they could have
contributed to off flavors.
Wild yeast: This test was conducted using Linís Cupric Sulfate, or
LCSM. This medium uses cupric sulfate to inhibit the growth of brewers
yeast. This medium ensures no contamination of non-Saccharomyces wild
yeast. Again, the information concerning numbers is the same for wild
yeast as the contaminants listed above under anaerobic and aerobic
bacteria. In other words, under 10 meets the industry standard, 10 or
more indicates problems. Typical off flavors produced by wild yeast
would be phenolic and band-aid flavors.