Automatic adjustment of residual extract and yeast quantities before the
bottle filler
Hildesheim, 29th of February 2007. The Weissbierbrauerei G. Schneider &
Sohn GmbH in Kelheim, Germany, is using a continuous in-line blending system
producing a mixture of top-fermented “Weissbier“ (beer brewed from wheat) and
pitching yeast for the filling process. This system with the “laboratory in the
production process“ analyzes and monitors automatically the apparent extract.
System manufacturer GEA Diessel and Tuchenhagen Brewery Systems as technology
partner applied for patent on the procedure and the system arrangement.
Due to the storage the apparent extract in the “Hefeweizen“ (wheat beer with
yeast) is not constant. In order to compensate it, the required quantity of
pitching yeast is added and the desired extract content is achieved.
The apparent extract is determined in the mixture. As this measured value is
influenced by CO2, the CO2 value is also determined in the product which serves
for the compensation of the measured value for extract.
The control is designed as cascade control. A ratio control is subordinated
to the control function. This enables flow rate fluctuations (e. g. during
shooting) to be adjusted quickly, und short-termed errors in the mixing ratio
can be compensated.
A constant apparent extract ensures that the required CO2 value is achieved
during the secondary fermentation in the bottle. This procedure makes a
contribution to secure a high-quality “Hefeweizen beer” (wheat beer with yeast)
in the market.
Traditional brewing method
Brewing of wheat beer with bottle fermentation is the traditional production
method. Especially some selected Bavarian breweries are still working with this
method. By means of this top-quality maturation procedure in the bottle a very
typical wheat beer flavour is achieved. With the active yeast in the bottle
there is practically no more residual oxygen content in the bottle.
*As
“pitching yeast” mostly pasteurized first wort (i. e. unhopped concentrated
wort) is used.