In a modern brewery, more and more quality related parameters are measured directly in the process. Benefits of such real-time measurement data are better plant control and optimization of several process steps without time delay. Also, for quality documentation purposes and charge traceability charts, analytical in-line data are of paramount importance. Visual parameters such as beer brightness and beverage color are evaluated by the quality-conscious consumer even before he starts to drink, and can influence his purchase decision.
Beer filtration and filling
The brightness of a beer – the absence of turbidity – is typically measured in EBC (European Brewery Convention) or ASBC (American Society of Brewing Chemists) units. In filtered beers the turbidity is typically smaller than 1 EBC, which equals 69 ASBC. Turbidity is directly measured in the outlet of a Kieselguhr or membrane filter, and in filling lines. In a dual scattering angle system both 90° and 25° light intensities are measured simultaneously. The 90° EBC/ASBC value is directly related to the concentration of small undissolved particles, for example beer proteins and glucanes. The 25° measurement plays the part of a “watchdog” in these applications due to its higher sensitivity to non-beer components such as yeast cells and Kieselguhr particles. Unwanted filter breakthroughs are detected very reliably and quickly via this scattering angle.
In the high-gravity brewing process the original-extractcontent is adjusted by blending beer with deaerated water. In some cases coloring beer is also added to produce darker beers. Beer based beverages are produced by blending the beer with soft drinks or flavor compounds. Typically, these blending steps take place after beer filtration. In addition to the determination of the original-extract-content, color measurements based on the EBC method provide important information on the final beverage appearance: consistent color and clarity being major goals of high quality. The beverage color – or to be exact, the yellowness – is measured by the absorbance of light of a characteristic wavelength. The simultaneous measurement of turbidity in the blending process and filling lines, further guarantees the absence of unwanted particles which might have precipitated during the blending process. The presence of unwanted particles can also originate from a bad batch of coloring beer or flavoring liquid.
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