Evaluating Particle Content and Filtration Efficiency in Beer


What could be more important than testing the quality of beer? I have my own traditional method, which involves downing large quantities and then observing the effects, but as a scientist I am aware that there are many flaws in this approach. While looking through the Beckman Coulter website I recently came across an interesting paper on how to use a Coulter Counter in assessing the particle content of beer and evaluating the efficiency of the filtration applied to it.

This is another good illustration of the diversity of uses to which Coulter Counters have been put since the initial application of the Coulter Principle in blood cell counting. In this case the results may not mean the difference between life and death, but being able to determine particle concentration at various stages in the brewing process certainly allows corrections to be made and ensures an enjoyable final product.

As any beer lover will know, no two beers are the same. Each has its own distinctive flavour and character – which may be affected by the nature and size distribution of its particulate content. Particle content can also affect the stability and, in turn, the shelf life of the beer.

A particular issue of concern to brewers is the chill haze effect found in some beers. When suitably chilled, a haze will appear. This will then disappear as the beer is warmed. The stability of the beer will determine the temperatures at which the chill haze appears and disappears. In a stable beer the haze will not be seen until the temperature becomes close to zero degrees C.

The chemistry behind this phenomenon involves complex compounds containing tannins (polyphenols) and proteins of high molecular weight. Their hydrogen bonds are sensitive to temperature and break down as the beer becomes warmer. When this happens, the breakdown compounds are allowed to enter a complex with the water molecules and dissolve.

Filtration of beer, which helps to clarify it in a non-additive way, has been practised as a tradition for many generations. It can be employed, together with fining agents, to ensure a beautifully clear and stable result.

If you would like to know about the technique for measuring particle size distribution and concentration, using the Multisizer 3 Coulter Counter, go to the Beckman Coulter website www.beckmancoulter.com, look for Coulter Counter Analyzers under the ‘Industrial’ button and then click on ‘Literature’ in the resources list on the right.