Finishing and Stability Session
Stefan Hanke, Bitburger Braugruppe GmbH, 54634 Bitburg Germany
Co-author(s): Georg Stettner, Bitburger Braugruppe GmbH, Bitburg, Germany
ABSTRACT: Stabilization has a long history in beer production. In former times, beer was stabilized by long storage in wooden barrels. During this very traditional and unsystematic method wood derived tannins and beer proteins reacted, and the resulting beer showed a higher colloidal and taste stability. With industrialization of brewing, wooden barrels disappeared, and filtration became a very important step in brewing as distribution channels became more complex and beer was shipped all around the world. Production of a brilliant, clear, and stable beer is the major aim of end-filtration, aside from the removal of yeast and turbidity after fermentation. Nowadays, for these stabilization purposes, the use of silica gel and PVPP is widely spread in the brewing industry. In recent times natural tannin based stabilization aids also came into the market. For these trials a highly purified high molecular weight hydrolyzable commercial tannic acid product was used in-line before end-filtration. Different dosage levels of tannins were applied to industrial brewed beer in semi-industrial scale filtrations. Concentration up to 2 g/hL of tannins were applied and compared to 35 g/hL of silica gel. The impact of these tannin dosages on colloidal and flavor stability were evaluated. All analytics were done according to international standards. It could be proofed that tannins are suitable for beer stabilization. A dosage of 1 g/hL was as efficient as the application of 35 g/hL of silica gel to increase the colloidal stability compared to an unstabilized filtered beer. With an increasing dosage level of tannins from 1 to 2 g/hL the colloidal stability of the final beer could be improved significantly. The removal of proteins was very specific to haze forming proteins because no impact on foam stability could be seen in our trials. The trials also showed that the concentrations of iron, aluminum, and vanadium in the final beer were reduced significantly by using the tannin product. The tannin treated beers came along with a higher antiradical potential (measured by ESR, T600 value), which is good for analytical flavor stability. The removal of the product was very good as no remaining tannins could be detected in the final beer. Also no negative impact on the taste and flavor stability of the fresh beers could be observed. The fresh beers that were stabilized with 1 g/hL of tannins showed a trend to a less lingering aftertaste (with the same analytical IBU) than the silica gel stabilized fresh beers. Besides the quality issues, economical and also ecological (lower filter waste because of lower dosage) savings could be generated by a use of tannins as a stabilization agent. Savings of up to 30% in stabilization costs could be possible. In our trials we showed that a natural tannin based stabilization agent is suitable to increase relevant quality parameters and improves colloidal and analytical flavor stability of filtered beer.
Stefan Hanke was born in 1980. From 1999 to 2004 he studied brewing science and beverage technology at Munich Technical University (Weihenstephan), graduating as an engineer with a Dipl.-Ing. degree. In 2010 he received a Ph.D. degree for his research on the influence of hopping technology on the harmony of beer. During his studies he worked for and received practical training at different German brewing and malting companies. Since 2004 he has been a scientific employee at the Lehrstuhl fuer Technologie der Brauerei I, Freising-Weihenstephan, Germany (Prof. Back). From 2006 to 2007 he headed the institute’s Small Scale and Pilot Scale Brewery Department. From 2007 to 2010 he was responsible for the HPLC and GC Laboratory of the Institute for Brewing and Beverage Technology (Prof. Becker) in Weihenstephan. Since 2010 he has been the head of the pilot plant of the Bitburg Brewing Group, Bitburg, Germany, and responsible for R&D issues of affiliated breweries.