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Home brewing: Sample degassing techniques

To produce a high-quality beer the fermentation process has to be monitored carefully. This article presents five techniques to degas samples before extract measurement. 

Stirring

One option is to stir the sample to remove dissolved gases in the liquid sample to prepare it for the extract measurement. When handling multiple samples a day it might be more convenient to employ a magnetic stirrer instead.

Using a syringe

An alternative to avoid bubbles in the hose of the measuring device is to use a syringe. The syringe is filled with the sample and a finger placed on top of it. Then the piston is pulled to create a vacuum and the finger is released to discharge the CO₂. This procedure has to be repeated at least three times to make sure that no gas is left in the sample. The used syringe needs to be large enough to leave some space for creating the vacuum: Only up to two thirds of the syringe should be filled up.

Sonication

To remove dissolved gases the sample can also be put into an ultrasonic bath for up to 10 minutes. When using this method, as well as the magnetic stirrer, it is important to cover the sample glass to avoid evaporation of alcohol during the degassing procedure. This might influence the measured result.

Shaking

One of the most convenient options to degas samples is to shake them. The vessel with the sample is closed, shaken and then opened to release the CO₂. Ideally a so-called Erlenmeyer flask with a rubber stopper is used, but a clean PET bottle can also be used. In this case the CO₂ is released by opening the screw plug. This process is repeated to successfully eliminate any gas bubbles in the sample. If the sample contains particles larger than approximately 1 mm it should be filtered before conducting the measurement. The rule of thumb is: The better the sample preparation is, the more accurate the result will be.

Going digital

For brewing in general, two things are indispensable: A fast, simple, and reliable measurement of extract in the wort before fermentation and fermentation control. In this way, it can be guaranteed that a brew becomes the desired beer. Designed for home brewing in particular, EasyDens, the digital density and extract meter from Anton Paar, meets these requirements and enhances the brewing quality in the long run. It determines the wort’s extract content, monitors the fermentation process with the help of a daily measurement of apparent extract, and gives the information brewers need to decide when it is time for bottling. The instrument is linked to an app on the user’s smartphone which automatically displays the measured data. By going digital homebrewers can work faster and more efficiently.