RUDOLF MICHEL (1), Udo Funk (2)
(1) GEA Brewery Systems, Kitzingen, Germany; (2) GEA Process Engineering Inc., Hudson, WI
For the fermentation and maturation of beer, the responsible
brewmaster has access to only a small number of tools to control and
optimize the processes: recipe parameters: temperature, pressure, and
time; process parameter: gravity of the wort, yeast strain; continuous
fermentation and maturation processes; and mixing of the tank The
complex mixture of fermenting wort and yeast cells normally reacts very
quickly to changes in the temperature and pressure profile or to
additional application of “stress”. GEA Brewery Systems has developed
the system ECO-FERM™ to improve the performance during fermentation and
cooling down to cold maturation temperatures. This provides a process
using jet mixing in a cylindroconical tank (CCT). A jet without any
movable parts is installed in the cone of a CCT using the Venturi
principle. So only one-third of the total flow inside the CCT is pumped
around with a circulation pump. Approx. 10% of the carbon dioxide
produced during fermentation is dissolved in the beer; the other 90%
bubble up to the liquid surface forming a bubble column in the CCT. This
bubble column leads to an upward movement of the liquid in the center
of the CCT and consequently to a downward movement at the cooled shell
of the tank. The jet in the cone provides a powerful support of this
natural upward motion. Improvement of this upward flow will keep a
bigger number of active yeast cells in suspension and, in addition,
yeast cells on their way down to the cone are sucked from the jet and
are re-suspended in the fermenting liquid. More yeast cells in motion
will speed up the chemical reactions. The hydraulic jet also improves
temperature homogeneity in the tank and significantly enhances the heat
transfer coefficient at the tank shell. This paper presents the first
results from an industrial application in a 2,660-hL CCT with worts of
14°P. For all trails, a wort batch of 5,320 hL was used to avoid
differences coming from brewhouse operations. The batch was divided into
a tank equipped with ECO-FERM™ and a reference tank using the standard
process of the brewery. The results cover process duration and
temperature homogeneity as well as analytical results of the beers,
including DLG tastings.
Rudolf Michel received both his engineering degree and his Ph.D.
degree from the Technical University of Munich at Weihenstephan,
Germany. He was a member of the scientific staff at the Institute of
Chemical Engineering at Weihenstephan, working on the mechanisms of
hot-break separation in a whirlpool tank and hygienic design of
armatures and pipework systems in the food industry. Rudolf’s industrial
experience includes an apprenticeship as a brewer and maltster at
Mahr’s Bräu in Bamberg, Germany. He joined GEA Brewery Systems in 2000
as director of brewing and technology and has been involved in major
brewing projects and research works around the world for GEA. Currently
he is leading the research and development team dealing with improvement
of brewing technology and environmental aspects of the brewing
industry. He is a member of DBMB and has published more than 64 papers.
