Properties of beer (part 2)

As stated in a previous blog post this post will be a follow up on the properties of beer and how to determine them. So without further ado, let’s jump right into it.

04refalc11-5To determine the alcohol percentage of beer, the beer needs to be degassed (eliminating the carbon dioxide). This is done by pouring about 20ml of beer (as I only needed a small amount) in a open flask and placing it on a slow shaker for over 4 hours. Hereafter the beer was poured over a filter into another flask to get rid of any contaminants from the air or yeast.
To determine the amount of alcohol a distillation is performed. This is basically the technique to make whiskey and gins. It’s a rather ‘old fashioned’ way of determining the amount of alcohol and is only done on a small scale. A distillation works as follows. The decarbonated beer is heated allowing it to evaporate. The formed gas consists of alcohol fumes and water vapor. The gas moves through a tube that is water cooled allowing the gas to go back to its liquid state (condensation) and is collected in another flask. This collection flask contains a small amount of cold water. This is necessary to make sure that the alcohol doesn’t evaporate again as it has a much lower boiling point than water. The density of the solution is determined by a ‘density measuring module’. All data is eventually used in the formula of Balling and the alcohol percentage is displayed in ml/100ml or %V as displayed on all in-store bottles.


Destillation setup

The head on a beer is a piece of art, it has to be perfect and, most importantly, stay. Unless you’re chugging a beer at 2am at your local nightclub, no one wants their beer collar to disappear in seconds. Measuring how long the collar of the beer lasts is described as ‘foam stability’. The equipment used for this test is called the ‘Nibem Foam Stability Tester’. To conduct this test you’ll need foam, a lot of foam. This can be done by injecting CO2 gas in the beer itself causing it to foam excessively. This foam is then captured in a standardized glass of 25cl. Once the glass is completely filled with foam it’s inserted into the machine which contains electrodes. These automatically detect the foam and follow the degradation of the foam in real time over a length of 30 millimetres.

Be sure to check the next, and last, post of the blog on how to determine the last properties of beer. Cheers!

Blanckey the Brewer


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