The reason for these beer analysis labs is for smaller breweries who do not have internal labs to quantify their beer's quality control to compare to sensory analysis and also confirm that the labels they are sticking on their bottles for retails sales also match up with whats ACTUALLY inside the bottle.
Bacteria Counting
Because of the yeast plating I have been doing, I figured to count bacteria we would be using more petri dishes. WRONG! 3M makes disposable gridded pre-made media that look like sticky notes, except the media on the sheets can be tailored to whatever it is you are trying to grow or identify.
I first unboxed commercial samples of beers that came in from all over the country. Then I went through and labeled a corresponding 3M sheet to the sample given. I then micro pipetted out a small volume on to the 3M sheet, put the cover down and let it bleed out. These sheets will then incubate for 2-5 days to allow bacteria to grow. If it does grow, it will show up as little red dots. The sheets that have red dots will be cell counted to get an approximate bacteria count for the batch.
For all subsequent tests, all beer samples were portioned out into new beakers and labeled again. Small samples were taken.
I also got to use this handy dandy tool which makes pipetting SO easy! It uses vaccum pressure to pull up an amount and push out an amount. Where has this been my entire life?!?
IBU's
To measure the IBU's (International Bitterness Units) in beer, you use a liquid extraction technique described HERE in great detail, but to sum it up, alpha acid (humulone) is insoluble in water. That is why you must boil your bittering hops for at least 60 mins to get any bitterness utilization and isomerize the humulone. But to measure IBU's after the beer has been packaged you must extract those alpha acids OUT of the beer. You take HCL to break acid out, then use 2,2,4-trimethylpentane (isooctane) to snatch the broken out alpha acids to then test.
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| trimethylpentane on top, beer on the bottom prior to shaking |
This sample with the HCl and trimethylpentane are then shaken for 15 minutes to emulsify, then centrifuged, then placed into a spectrophotometer where are wavelength of light is used to measure its absorbance. A final calculation is made with this value, and voila, IBU's!
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| This is the spectrophotometer |
SRM (color)
Just like the IBU's, the spectrophotometer was used, however no preparation was needed of the beer sample, other than off gassing the beer and filtering it if it was cloudy, such as an wheat based beer.
Density & Alcohol %
This is where the expensive equipment was used. Density and alcohol % of an alcoholic beverage are linked, as long as you have pure ethanol in pure water. It is a simple D = M/V equation. However with beer, you have other solutes in the solution. So you need to separate the ethanol from the beer through distillation (which is time consuming) OR! you can use a super expensive Anton Paar Alcolyzer and Density meter that will report all sorts of fun facts such as the alcohol %, but also calories, extract, degree of fermentation, and others!
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| This machine setup and automatically churn through up to 20+ samples in one go |
Conductivity & pH
Finally the last tests run were conductivity and pH. pH is an obvious choice to measure, since pH really influences how a beer is fermented and of course its flavor (think sour beers and its lower pH). However! have you ever considered testing the beer's conductivity? The reason to do so is to check the salts present in the beer and compare that to your water chemistry used in the brew. Do they compare? Are you getting any off flavors that you think are due to too low or high salts? This test might help with that.
Overall Takeaway
Considering I am very early on in my school career for fermentation sciences, this has A) given me a heads up of what to expect. B) A possible career field within fermentation to pursue and C) more general knowledge of the field I am heading into.
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