filtration seminar papers
Since Enzinger introduced the filtration in 1878 many new originations
came up. [8] Through the last years the Public Relation pushes the sterile
filtration instead of thermal treatments. Trendsetters were Japan and
North America.
Filtration belongs to the oldest technical treatment. It is just a separation of solid and liquid substances in a suspension and is the last process of the beer production. The yeast, protein and carbohydrate particles, which must be removed from beer to achieve the necessary degree of clarity, are of small size and are compressible. Any attempt to remove this material using a single filter medium, for example a filter sheet, would result in a rapid blockage of the filter and make this method impracticable. The high resistance to flow offered by the accumulation of material on the filter means that it is described as having a low 'Permeability'. These problems may be overcome by injecting a suitable material into the beer stream, referred to as the 'Filter-Aid'. This forms, together with the yeast and other suspended solids, an almost incompressible mass on the filter medium and referred to as the 'Filter-Cake'. This is capable of maintaining the flow of beer and is described as having a much higher permeability. Filter-aid added into the flow of beer this manner is referred to as 'Body-Feed'. But at first filter aids (very coarse ones) have to form an intermediate layer bridging the gaps in the sieves, leaves or cartridges. This so called first precoat layer acts as a support for the subsequent finer precoat or second precoat layer and later on the body feed.
An important characteristic quality of beer is its brightness and its product durability. The beer of retail quality will be filtered after maturation , where a certain sedimentation of haze particles has taken place. Filtration belongs to the oldest technical treatment. It is just a separation of solid substances in a suspension. The suspension, consisting of a discontinuous phase, runs through a porous filter aid. While this process the solid particles (substrate) are sedimented by the filter aid and the filtered liquid (filtrate) leaves the filter aid in a clear
condition. It is distinguisched between surface- and depth-filtration. Cake filtration with a continious kieselguhr dosage belongs to the surface-filtration, but trub particles are also separated in the deeper regions of the cake. The pressure differential is the outer force which keeps the fluid on the run against the resistance of the filter, filter-aids and separated substrate.
The top fermentation is the oldest method to produce beer. Since the 70th the production of wheat beer goes up in Bavaria. The reason was the boringness of the bottom fermented beers. Top fermented beers were stand for more individuality.