The Coulter Principle or the Electrical Sensing Zone (ESZ) technique may be used for particle concentration and size distribution measurements in beer with the help of an appropriate electrolyte solution. The sample preparation involves dissolution of some amount of beer in the electrolyte solution.
A Beckman Coulter Multisizer 3 is then used to analyze the resulting solution to determine the concentration and size distribution of the particles in beer. This article discusses the evaluation of the final product filtration efficiency in beer using the Multisizer 3 Coulter Counter.
Significance of Particle Analysis in Beers
Determining the concentration of particles present in beers helps assessing and/or rectifying several processing steps from the brewing stage all the way through to the final product. The chill haze effect is common in beers. The temperature at which the chill haze effect appears and disappears in beers is based on their physical stability.
Complexes of high molecular weight proteins and polyphenols are part of the haze, forming weak hydrogen bonds that are sensitive to temperature changes. As a result, these hydrogen bonds break into form compounds when there is an increase in beer’s temperature. These compounds in combination with water molecules form a complex and go into solution.
Filtration is used for beer clarification, and yields brilliantly clear beers with better temperature stability when used with fining agents. The concentration and size distribution of particles in the beer final product affect its flavor and characteristics, as well as its stability and shelf life.
Advantages of the Multisizer 3
The particle content in beer can be rapidly, conveniently, and accurately determined with the help of the Multisizer 3. The automatic method provides reliable results without the interference of operators, thus allowing the comparison of data obtained from different work shifts and/or breweries.
Experimental Setup and Procedure
The final product is evaluated using a 50 µm aperture tube. The Multisizer 3 is configured and calibrated as described in the user manual. The instrument is set to Volumetric Mode for particle concentration measurement. The run volume selected is 500 µL. The Multisizer 3 Software is loaded with background information to measure the particle concentration in the Isoton.
Around 20 mL of Isoton® II is placed in an Accuvette® II. The Accuvette® II consisting of the Isoton is placed in the analyzer and the aperture tube is flushed prior to the run. The background is set on the Multisizer software. The background is subtracted automatically from all successive analyses until setting a new background.
The Multisizer 3 Software is loaded with the sample information to determine the particle content in the beer. After the gas removal from the beer, around 15 mL of Isoton® II is fed into a 20 mL Accuvette® II, followed by pipetting 5.0 mL of beer into the Isoton. The volumes may differ depending on the types of beer.
The Accuvette is capped and stirred gently to make a solution without bubbles. The sample is prepared just before the analysis. The Accuvette® II consisting of the sample is placed into the analyzer and the aperture tube is rinsed prior to the analysis. The aperture and the electrode are rinsed after each run prior to analyzing the next sample.
Evaluation Results of Particle Content in Final Beer Product
The experimental results are presented in the following formats:
|FULLER’S LONDON PRIDE
|SAM.ADAMS WINTER LAGER
|THE KNIGHT’S ALE (WHITE ALE)
||15.36 x 106
||1.545 x 106
||1.368 x 106
||1.278 x 106
||Particles/ml 1-30 µm
|Coors Light (USA)
|Corona Extra (Mexico)
|Fuller’s London Pride (UK)
|Grant’s IPA (USA)
|Miller Lite (USA)
|Miller MGD (USA)
|Presidente (Dominican Republic)
|Samuel Adams (USA)
|Sam.Adams Winter Lager (USA)
|The Knight’s Ale (Belgium White Ale)
||15.36 x 106
The sample selection is random from a pool of available brands and types of beers with different manufacturing dates, storage conditions, and length of time. Hence, the purpose of the reported results is not a comparison of the different brands of beer, but showing the way of presentation of the results (Figure 1).
Figure 1. Determination of size and concentration of particles in beer final product.
The instrument is configured and calibrated and the aforementioned procedure is followed in the same order to conduct the beer analysis before and after filtration. The results prior to and after filtration are then compared for determination of the filtration efficiency (Figure 2). The percentage of difference in the particle count before and after filtration provides the percentage of filtration efficiency. The following table summarizes the comparison:
|Particle Diameter (µm)
||Filter IN Number per mL larger than
||Filter OUT Number per mL larger than
Figure 2. Filtration efficiency.
The filtration process may also be observed for specific size ranges. The data on the number of particles filtered out is often inadequate to define the filtration deficiency. Hence, certain size range needs to be targeted in order to refine the filtration process.
This information has been sourced, reviewed and adapted from materials provided by Beckman Coulter, Inc. - Particle Characterization.
For more information on this source, please visit Beckman Coulter, Inc. - Particle Size Characterization.