Improvement of measurement of haze during final beer filtration.

Wackerbauer, K., Evers, H. and Kaufmann, B.

Abstract
Some beers which appear clear immediately after filtration develop a haze or a sediment a few days later. This problem is obviously not detectable by conventional haze meters during filtration or packaging. Experiments aimed at improving the performance of brewery haze meters in order to detect beers afflicted by this problem were carried out using beer samples spiked with coarse and fine kieselguhr, silica gel, xerogel, PVPP, starch, yeast and bacteria, which were tested by a variety of photometers using different wavelengths and angles of measurement. Instrument tests were also carried out during production filtering operations in a commercial brewery. It was found that using white light at a measurement angle of 90 degrees can detect fine particles but sometimes fails to detect coarse ones, whereas at angles from 13 to 25 degrees the reverse applies. An instrument using infrared light at 90 degrees produced results similar to white light at 25 degrees. The authors therefore recommend the adoption of instruments using two wavelengths or angles of measurement simultaneously.
Keywords : beer comparative test equipment haze measurement photometry