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QC day sheds light on craft brewing


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 general.

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 in general.

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 contamination.

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 program.

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 dark.

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.