Simultaneous Filtration and Stabilization of the Beer: Potential for Oxidized High-Density Polyethylene (OxPE) to be Used as Filter Aid

J. Am. Soc. Brew. Chem. 70(4):280-286, 2012 For decades, kieselguhr has been the most common filter aid for beer filtration. However, costs for disposal are severely increasing and brewers today are concerned about replacing kieselguhr filtration by a greener technology. Filtration trials were carried out with the regenerable filter aid oxidized high-density polyethylene (OxPE) on a pilot-scale candle filter using green lager beer from settling tanks. OxPE has an average particle size distribution of 37 mu m and its outer surface presents nodular structures. The porosity of the OxPE media is 0.6 compared with 0.85 for kieselguhr. OxPE retains a good amount of haze and yeast cells without clogging; however, the expected clarity was reached only when using Brewtan. The use of polyvinyl-polypyrrolidone (PVPP) mixed with the OxPE filter aid (25/75%) showed the best results for filtration because of the shape of PVPP particles and their slight compressibility. Regeneration is one of the most important steps to achieve because the filter aid has to be reused as many times as possible while keeping its properties of retention toward haze and yeast cells. OxPE proved to have very good resistance to aggressive regeneration conditions, and filtration trials carried out after such an operation confirmed this.