As beer does not only have to exhibit a perfect odor, taste and foam, but brightness is also demanded, the beer must be artificially clarified, i.e. filtered. This procedure involves the advantage that not only turbidity constituents, such as protein, tannin compounds and hop resins, are retained here, but also yeasts and possibly bacteria. The filter is usually arranged on the filling path between the fermenting/storage tank and the filler. For example due to different raw material properties or different process managements, different beers have varying filterabilities, meaning that a varying proportion of ingredients per time unit and filter surface can be filtered out of the beer or wort, and consequently the service life of the corresponding filters is varying. One problem in filtration is that for example in case of kieselguhr filtration, a fast pressure increase at the filter surface might occur, resulting in a shorter filter service life.
Up to present, one has assumed that beers having similar compositions, e.g. similar proportions of beta glucan, protein contents etc., and a similar viscosity have similar filterabilities. However, internal tests revealed the following:
FIG. 3 shows, as an example, the proportion of beta glucan, total nitrogen and magnesium-precipitable nitrogen, as well as the viscosity for a standard beer and a beer that was manufactured by means of a mash vessel in which a vibration unit (or several vibration units) is provided which oscillates the mash. Such a mash vessel is illustrated, for example, in DE 10026723 A1. Although the beers manufactured with and without vibration unit(s) have essentially the same compositions, as is shown in FIG. 3, these nevertheless have different filterabilities, as can be clearly seen in FIG. 5.
In FIG. 5, one can see the increase in the pressure difference in a kieselguhr candle filter. The left half shows the pressure increase of the beer 1 (α1), the right half shows a classically brewed beer (α2). One can clearly see that the pressure increase in the left half has a flatter progress (α1<α2). Thus, in beer 1, a higher amount of beer can be filtered until the maximum admissible pressure difference at the filter is reached. However, this means that with the former analysis techniques, i.e. for example the determination of the beta glucan proportion, the viscosity, etc., no reliable statement on filterability can be made.